PAINTING SUPPORTS, WITH A FOCUS ON PANELS AND PANEL MATERIALS

INTRODUCTION My search for a better painting support began because I noticed that the 1/2” cabinet-grade birch plywood panel stock I had been using for painting supports was becoming less reliable, primarily in its resistance to warping. Finding a problem-free painting support is a common conundrum, and not long after starting this research I heard about an artist who had begun a major commission on panel, only to run into warping. (She had to repaint some panels twice.) I wrote to her to see how she had solved the problem and received the following:

“Yes, it was very maddening and frustrating about the warping. The final panels were constructed by Dovetail, a furniture company. They used 3/8" MDO panels front and back and the panels measured 38" x 34" x 1.5" with a hollow core. The back panels had several 1" holes to allow for air to circulate. Each weighed approximately 18-20 lbs. They received three coats of Winsor & Newton acrylic gesso primer on the painting surface and one coat on back and sides. I'm keeping my fingers crossed. Because this work will hang in a non-climate controlled area I, too, had to use materials that had a degree of permanency. I do not contemplate using panels again.” It is clear that this artist went through a good deal, and probably ended up spending a lot of money to have a furniture company construct custom panels for her, all of which may have put her off using panels again. Further, even after all this effort and expense, I doubt that her solution was archival.

In my search for painting supports, I hoped to find panels that would have flat, smooth surfaces that would stay straight without bracing (since bracing adds considerably to the time of preparation), though as I inquired, I discovered additional issues relating to the longevity of works on panel that needed to be taken into account. Initially, though, I determined the ideal panel would also be lightweight, affordable, and available without the need to place massive orders. Most of my search was for plywoods, since wood is the traditional material in the history of painting on panel, so the method of transforming such a panel into a painting surface seemed well established. (Given the processing of today’s wood products, however, that is not completely the case. *) Depending upon what I found, I figured some compromise in some of these criteria might well be necessary. A few promising leads turned into frustrating dead-ends: A. ApplePly: “ApplePly is a premium quality veneer core panel constructed from uniform laminations of solid grade 1/16" Alder and Birch. This all hardwood core produces a strong, lightweight panel with a minimum number of voids and a naturally attractive edge. ApplePly is available from 1/4" through 1-1/4" in thickness and 48" X 96" and 48" X 120" panels.” (www.statesind.com/prod/consumer_2b2.html) I found a

couple of distributors in Richmond on the ApplePly website, but when I went to their warehouses, they said they no longer carried that product. ApplePly is made by States Industries, Inc., a west coast corporation. In calls to them I found that there are no longer distributors for the product on the east coast. In addition, they have temporarily shut down production of it because the wood they use come from Russia, and a bad winter there last year means they can’t get the wood. B. ArmorCore: “ArmorCore panels combine the low weight and high strength advantages of veneer cored panels with the superior flatness and higher density of MDF [medium density fiberboard]. ArmorCore panels are stiffer, lighter and stronger than composition panels of comparable thickness, yet the MDF crossbands match the best composition surface characteristics.” (www.statesind.com/prod/ind_2a4.html) ArmorCore is also made by States Industries, and there are no east coast distributors.

C. Baltic Birch. Sometimes called ‘Russian Birch’, Baltic Birch is a hardwood

multi-ply (more plies than usual) light color plywood, but it seems to be only available in B and B/B surfaces, which is not top grade (meaning it may have cut-outs or knots on both sides). The Russian source makes me wonder how broadly available it will be, given the last winter. No gaps and hardwood through the plies, it should be worth pricing out.

“Baltic birch uses birch as the substrate and is probably the most common type of HDP [High density plywoods (HDP) typically come in either maple or birch specie. Unlike common plywood, HDP has many more plies, is generally void free, and uses a stronger species than fir. HDP is commonly used for drawer side material as it is strong, stable, and has a moderately attractive edge]. This will come in 5' x 5' sheets. For a 1/2" sheet, there are typically 7 to 9 plies. Being birch, the surface does not finish as nicely as the maple counterpart, and there is a tendency for splintering at the edge of a machined cut.” Rick Christopherson; (www.waterfront-woods.com/Articles/Plywood.htm)

D. Marine grade plywood: “Plywood panels manufactured with the same

glueline durability requirements as other exterior panels but with more restrictive veneer quality and manufacturing requirements. The grade is particularly suitable for marine applications where bending is required, as in boat hulls.” (Engineered Wood Association Panel Handbook and Grade Glossary American Plywood Association APA 1997) This grade initially sounded good because the interior plies are clear, or gap free, making stresses more even. It turns out this is because marine plywood is bent for hulls and needs to bend evenly. This would still have been OK if the face veneers available were good, but quality face veneers for marine plywood are selected for appearance (color and grain pattern), and care is given to matching colors and patterns that, for my use, would simply get painted over. Good marine plywood, therefore, is quite expensive (over $100 for 1/4” 4’ x 8’ sheet).

E. PVC Panel: “RIGID PVC FOAM BOARD; A LIGHTWEIGHT, TOUGH, RIGID PLASTIC BOARD WHERE APPLICATIONS ARE ONLY LIMITED BY IMAGINATION” www.denversignsupply.com I have a piece of this I picked up from a sign maker, and it appeared to be a great product: light, rigid, cheap, and cradles could

easily attached with PVC glue. The bad news, of course, is the material PVC (polyvinyl chloride), which has lethal associations in its production, off-gassing, and destruction or disposal.

Further, the opinion of most of the people I talked to who work with plywoods for

a living is that large panels, especially the thinner (lighter) ones, need reinforcement or a cradle to stay flat. (A cradle is a rigid support frame attached to the back of a panel to prevent warps, bowing, cupping, and cracking.) I decided that another side of my research should be to build some cradled panels with materials locally available to see what combinations and procedures produced the best result. The following report therefore begins with a section on homemade panels, followed by a section on alternatives to plywood panels and a third section on commercially available panels. This is not an exhaustive study, nor are my sources cited according to any academic format, though they are generally identified in such a way that they can be easily traced. This is simply the record I kept of my own search for a good painting support. Bold type indicates supports I tried during this project. * See PROVISO at the end of the HOME-MADE PANELS section.

David Dodge Lewis 9/01/08

HOME-MADE PANELS [in the order undertaken] The following tests were experiments primarily to find an effective and

inexpensive method to cradle lightweight plywood panels with flat, tight-grain face veneers. By way of explanation, four common types of warps or bends are: bow (a bend running with the grain, or the length of a board), crook (an edge bend), cup (a bend running across the grain, or the width of a board), and twist (ends of a board bent in opposite directions). 1. 1/4” birch plywood cradled with 1” x 2” fir. This is a combination I have used in the past that had worked well, though this time I did not construct an independent cradle frame ahead of time. The fir came in 1” x 4” boards, which I ripped in half to give a more narrow depth to the panel and an exposed surface for gluing. Each cradleboard was mitered for the corner and was glued down separately. When finished, I drilled across the miter and glued in a dowel to link the corners.

The advantages in proceeding this way are several: gluing a pre-constructed cradle to a panel requires many clamps, the cradle tends to slip on the glue, and the glue may start setting up before one gets all the way around the panel with clamps; the panel should be set flat on a raised surface just somewhat smaller than the panel so that there is room for the clamps; if there are nails in the corners, as is generally the case when an independent mitered cradle is constructed, it is risky to trim the panel later, if necessary.

Gluing and clamping seemed to proceed well, but after the primer and gesso had been added (unless otherwise indicated, primer and gesso are applied with a “smooth surface” roller), there seemed to be a slight cupping of the panel on one long side. (The grain ran across this panel.) I initially thought this was because the plywood was older, very dry, and porous, and it had cupped some, bending the cradle; it may, however, have been that one of the cradle boards bowed after being ripped, as sometimes happens. In researching commercial producers of artists’ panels, I found a website with panels cradled with plywood, which seemed worth a try.

To keep the cradle from warping (further) after the fact, I used a urethane to seal it.

above: grain of birch plywood panel in raking light 2. 1/4” birch plywood cradled with 3/4” birch plywood strips roughly 2.75” wide. I applied one layer of priming to the front of the panel so that if the bend in #1 was due to a porous veneer, the plywood could bend before being glued down. It bowed slightly toward the front, but the next morning it was actually bowed away from the front. The plywood cradle strips were not mitered, but were butted, and the plies were parallel to the panel itself. While I cut enough birch strips for two panels, some of the strips developed bows, and I was lucky to have enough straight ones to make one panel. The long sides of the cradle went down first, and all seemed straight. When the first short piece was added between the long pieces, the fit was close, and I noticed that there was a slight cup forward in the middle after the glue was dry. (The grain ran with this panel.) I cut the second short piece shorter in case the tight fit was somehow pushing the center out. Added layers of primer/stain-sealer and gesso seem to make the cup even more pronounced, and I thought that unless it flattens out, this panel would be unusable. Cup on the short side was 1/8”. Painting on the back of the panel may have done a little good, but for some reason, it doesn’t move things as much as painting on the front does. While not ideal, this panel ended up usable. 3. 1/4” oak plywood cradled with 3/4” oak plywood strips roughly 2.5” wide. I applied one layer of priming to the front of the panel so that if the bend in #1 was due to a porous veneer, the plywood could bend before being glued down. It bowed markedly

toward the front, but the next morning it was nearly flat. The cradle strips were not mitered, but were butted. Again, while I cut enough oak strips for two panels, some of the strips warped, and I was lucky to have enough straight ones to make one panel.

The long sides of the cradle went down first, and all seemed straight. As with #2, when the first short piece was added between the long pieces, the fit was close, and I noticed that there was a slight cup forward in the middle after the glue was dry. It may be, though, that the panel has a slight tendency to cup, or bend across the grain of the veneer, since in the three first tests, what bend there is is most pronounced across the grain of the veneer. None of these bends is so great as to make the panel unusable, but it is frustrating, since it should be possible to get them completely straight.

Added layers of primer and gesso seem to make the cup even more pronounced, and again I feared that unless it flattened out a lot, this panel would be unusable. It did seem to flatten out pretty well, but it is plain why oak plywood is not used commonly as a painting surface: Three layers of gesso and the grain is still pronounced. Also, in spite of the Kilz primer, a stain seemed to move up from the oak panel. This panel was unusable.

above: grain of oak plywood panel in raking light below: grain of oak plywood panel coming through priming and gesso

4. 1/4” birch plywood cradled with 1” x 2” poplar after priming and gessoing. (These are finished 1” x 2” boards from Lowes, and since I did not rip them from wider boards, these stayed as straight as when I bought them.) After 3 layers each of Kilz (the primer/stain-sealer) and gesso, the cup on the short side was a sizable 3/8”. I turned the panel over, ran a line of masking tape down the edges to protect the area where the cradleboards would be glued, and rolled on some Kilz to see if it is possible to pull the cup back in a little before adding the cradle. The Kilz on the back almost completely flattened the panel, since it was not secured to a cradle. I put on a second coat, which actually cupped it toward the back. To balance, I put another layer of gesso on the front, then took off the tape and began gluing the poplar cradleboards to it. I butted the corners, short side up against long side, and

eventually doweled the corners, since I saw on test #3 that pressure near the corner could bend the panel a little in the area of the gap between cradleboards. The sides came out quite flat. The only down side was that it has a slight twist so that, if laid flat on the floor, one corner wants to be up a little. It can go flat and stay that way with just a minimum of pressure, so it isn’t too big a problem. This may come from not having the corners mitered, since mitered corner contact with sufficient surface area would reduce twisting. I tried putting small plywood triangles in the four corners, but it did not help. I added a turnbuckle (see below) and that straightened out the twist. Since panel #5 also had a twist, I added a turnbuckle to that one, too, which seems to have worked. In the future, I will be sure to prop the panel up evenly when gluing and clamping each side to help keep it flat.

above: turnbuckle added to straighten panel; one end is attached to a screw eye near the

panel, and the other is near the edge of the cradle so that the force of the turnbuckle pulls the panel into alignment.

5&6. Two panels of 1/4” maple plywood. Maple is a great surface (see photo below), with a tighter grain than even birch, so it costs more; I had to special order a sheet for $35. I put three layers of Kilz on the back first, with tape around the edge to protect the area where the cradle would be glued. The panel developed a slight bow and cup, making it dome toward the painted side (the back). This seems to be a pattern; probably the damp paint soaks into the grain, expands the wood, then dries with the grain is somewhat expanded. Subsequent layers of Kilz added to the front seemed to flatten the panel out somewhat for the same reason. I put on only two layers, as I was running out of Kilz and that should be enough. Then I put three layers of gesso on over those, and the panel began to bow and cup the opposite way. To flatten it out a little, the next day I put one layer of watered-down gesso (the last of it) onto the backs of the panels. The cradle was added to the first panel (#5) one side at a time, from very straight poplar 1” x 2”s, long sides first, then short sides butted in between (since the boards I have are 6’ long, so I get two short sides from one board). Reflecting upon the twist in #4 and finding a little in this first maple panel, the second cradle I mitered the corners. I also did the gluing on a table so that the panel lay flat with the clamps hanging over the edge. These two things (mostly the use of the table) minimized the twist.

above: grain of maple panel in raking light 7. 1/4” birch plywood with 3/4” oak plywood cradle, on edge. Having seen some professional panels re-enforced with plywood on edge, I thought I would try it. I mitered the corners, since otherwise the veneer might catch on objects and tear. This is also the first panel on which I used Safecoat Safe Seal (see below) to reduce offgassing and acid leech into the paint surface. The cradle was added before any paint on the panel. I began priming with two coats of Safe Seal, sanding after the first coat, then three coats of Kitz and three of acrylic gesso. I don’t know if it is the Safe Seal or the plywood strips on edge (probably the latter), but the panel is perfectly flat. It would be great if I didn’t have to balance the paint on the front with paint on the back. Each of the above 1/4” plywood panels with cradles weighs in at about 10 pounds for a 3’ x 4’ panel. 8. Dibond is “an aluminum composite material (ACM) made of two pre-painted sheets of .012" aluminum with a solid polyethylene core.” (SEE ALTERNATIVES TO PLYWOOD PANELS, 1. Aluminum Panels, B. Dibond.) The 4’ x 8’ x 4mm sheet arrived with a plastic protective surface on one side. I cut two 3’ x 4’ panels and a series of smaller panels on a panel saw. I had to trim some, for the plastic core stuck out about an 1/8th of an inch beyond the aluminum on one long side. I had to file the edges, for the cut aluminum was rough and sharp. The 3’ x 4’ panels are light weight and have some flex, but could be held flat in a frame. Golden Acrylics suggested that the priming to use on these aluminum panels is Sherwin Williams DTM Bonding Primer, an industrial & marine coating. It is a “waterborne, acrylic emulsion, adhesion-promoting bonding primer designed to be part of a system for coating pre-finished metal siding.” It has a shelf life of 36 months unopened, but is available only in gallons (at least around here) and is expensive ($84.85, but I got a 20% discount). I ended up using less than a quart on this first batch of panels. Another priming option was mentioned to me by John Oldham from Harbor Sales: “The paint on both products is a baked on enamel, the only difference you should see is in the finish- Dibond is a satin matte and the Lusterboard is gloss. [This is noticeable.] That primer [DTM Bonding Primer] will work, but I also have customers that use the factory finish as the prime coat. They will lightly scuff the factory finish to promote paint adhesion, wipe the panel with alcohol to make sure it is clean, and repaint with the new color.” The Sherwin Williams salesman recommended that the surface be cleaned with

something like Windex to really clean it, and to apply the primer with a foam roller for a smooth finish; no scarring or scoring of the surface is necessary. Being an acrylic, it is a good primer for the acrylic gesso, but one needs to wait at least 4 hours before applying the gesso. One coat should be sufficient. It is off-white, so it is easier to check for coverage. Stirring the primer, it felt gritty, which is not surprising when one finds out it has quartz, calcium carbonate, and mica in it; also titanium oxide and zinc oxide, which helps account for the plaster-like cool-gray white. I peeled off the protective layer(s) on the Dibond, checked for dents and scratches in the surface to see which side up to put it, and cleaned them with glass cleaner. The foam roller didn’t make the primer go down any more smooth than a nap roller for smooth surfaces. The roller slid some, which is not surprising, both surfaces being so smooth. One thing I noticed in rolling out the primer is that the Dibond has a duller finish on the aluminum, more like a matte plastic, whereas the LusterBoard has a shiny finish. The primer also seemed to go down more evenly on the LusterBoard. I hope they bond equally well. After it was dry, it was possible to see that the coverage had not been 100% on all panels (since the enamel underneath is reflective, but the primer is matte), so I went back over a few. The primer smells of ammonia (being acrylic), and took several hours to dry because the room was cool. I also had to re-file the edges of some, since the aluminum was still sharp. I began putting on the gesso with a foam roller designed for very smooth surfaces. It sprayed gesso everywhere, much more than a knap roller does, and left tiny bubbles to dry in the gesso. When dry, the bubbles had to be sanded down, so I have dispensed with the foam roller and replaced it with a knap roller for smooth surfaces (which is what I normally use). The drying was taking a long time in the cooler studio, and the coverage wasn’t as good for some reason, so after I finished painting for the day, I moved the panels upstairs to a warmer and drier room for their final layers. The 3’ x 4’ panel weighs about 11 pounds. 9. LusterBoard is also an aluminum composite material (ACM) made of two pre-painted sheets of .012" aluminum with a hardwood core of a premium grade, rigid, exterior furniture-grade plywood. (SEE ALTERNATIVES TO PLYWOOD PANELS, 1. Aluminum Panels, C. LusterBoard.) .) The 4’ x 8’ x 1/2” sheet arrived with a plastic protective surface on both sides. I cut two 3’ x 4’ panels and a series of smaller panels on a panel saw. I had to file the edges, for the cut aluminum was rough and sharp. The 3’ x 4’ panels are slightly heavier than 1/2” plywood since it appears to be 1/2” plywood with an aluminum sheet laminated to each side. The 3’ x 4’ panels seem very flat and straight; there are some voids exposed by the cuts that need to be filled. Having a 1/2” plywood core, a 3’x 4’ panel of LusterBoard weighs about 18 pounds. (For priming LusterBoard, see priming of Dibond, immediately above.) 10. 1/4” mdf (medium density fiberboard) core plywood, maple faces, with 3/4”

plywood cradle, on edge. This is rather like an untempered Masonite with maple veneer on both sides. Advantages include consistent and true thickness, no voids or fissures in the core, no telegraphing (show-through on a smooth overlaid plywood panel surface of underlying grain or defects; see photo below), and the even surface of the fiberboard gives the veneer a consistent surface to adhere to. “MDF offers great stability and is the least likely to react when subjected to a measurable change in environment. It offers a very smooth, void-free surface for veneer lay-up. MDF has greater strength and screw holding properties than PBC. Like PBC however, MDF is one of the heavier core options. This core is especially well suited for thin panel applications such as door inserts and paneling.” (The Wurth Wood Group http://www.wurthwoodgroup.com/PDFs/WOOD_SECTION.pdf) Disadvantages: heavier than veneer core, doesn’t hold screws as well, and dangerous dust to inhale (be sure to cut this outside and with a respirator if possible). I found a maple face (B grade) over MDF core for $53.61. “B Grade = Where the natural characteristics and appearance of the species are desirable. Pin knots and small burls, combined average 16 - 8 can be 1/4”; conspicuous burls, maximum 1/2”; sound and repaired knots in combination, 4; repaired knots, 4; mineral streak, yes; vine; yes; rough cut, slight; blended repaired tapering hairline splits, fours 1/8” x 8” ” (The Wurth Wood Group) A 3’x 4’ panel costs about $20.00 (w/o cradle) and weighs 12 lbs. (w/o cradle) or 16 lbs (w/cradle). I glued and clamped birch plywood on edge as a cradle with little problem. After one coat of Safe Seal on the back, two on the front, and three layers of Kilz on the front, I noticed a pronounced bow toward the front. I put a second coat of Safe Seal and layers of Kilz on the back, but it didn’t work. I had to cut the cradle off and make the panel smaller, with a new cradle. In the mean time, I got another 3’ x 4’ sheet of mdf maple plywood, put tape along the back edge (to make a gluing surface for the cradle), then sealed the back with the Safe Seal and a couple of layers of Kilz. Then I put Safe Seal and a couple of layers of Kilz on the front and started gluing on a cradle. This panel was flat. As a result of a couple of experiments to see whether it was the panel or the cradle that caused the bend mentioned above, it seems it was the panel. I prepared smaller panels of mdf core plywood, back and front, and found that it tended to bend toward the painted side (either front or back) while the application was wet, but eventually flattened out. Once I got to the gesso layer, I put 3 coats on the front for only one on the back, but it still flattened out. I also glued a 40” cradle board (3/4” plywood on-edge) to a strip of 1/4” plywood, and the result was straight when it dried. I then sealed the cradle, and when that dried, it was still straight. I am guessing that if a cradle is glued down early, the wood on the front has a chance to expand a little when sealed or painted, but the wood on the back does not, and the result is a bow to the front.

above: voids in core plies telegraphing through the birch face veneer

HOMEMADE PANELS: SUMMARY The best prospects I have found when it comes to homemade panels, taking into

account quality & archival stability, price, weight, construction effort, and availability of materials, are as follows:

1. If you want a lightweight or thin panel and can put up with a little flexing in

larger sizes, the 1/4” Dibond is the best bet. Small panels stay rigid, but at the 3’ x 4’ scale, there is some flexing, though this could be held in check by a frame. Dibond panels are the same on both sides, so can be painted on either side, unlike B/C plywood, which has a better side. Unlike plywood, since there is nothing to warp or absorb water, no cradle is necessary, and the surface stays quite flat. Keep in mind that there is an extra priming step to make the enamel surface bind with subsequent paint layers. Dibond can be dented, but that is a risk with almost any panel. Pay special care to the corners, for if they come in contact with another panel, the aluminum can scratch the surface.

2. If you want a more rigid panel and don’t mind a little weight, 1/2” LusterBoard

is a good option. With a 1/2” plywood core, there is no need for a cradle, at least up to 3’ x 4’. As with Dibond, either side can be the painted surface. Keep in mind that there is an extra priming step to make the enamel surface bind with subsequent paint layers. LusterBoard can be dented, but that is a risk with almost any panel. Pay special care to the corners, for if they come in contact with another panel, the aluminum can scratch the surface.

3. If you don’t mind building a cradle (and cradles can be used as a presentation

element, almost like a frame), 1/4” mdf (medium density fiberboard) core plywood, maple faces, with a 3/4” plywood on-edge cradle is a good choice. The mdf core gives good stability and reduces the chance of warping, and since the mdf core is flat, there are

no gaps or voids telescoping through to the face veneer. This keeps the surface quite flat. Remember to use a sealer/primer, like Safecoat Safe Seal for off-gassing and Kilz for stain-sealing, before gesso. One advantage to this choice is that, unlike Dibond and LusterBoard, mdf core plywood is a generic and does not rely on the survival of a single company. It also may be more broadly available.

It seems that to avoid warping the panel, one should tape the edges of the back of the panel (to give a gluing surface for the cradle) and put on the Safecoat and primer (like Kliz), and on the front put on the Safecoat and primer (like Kliz) and one layer of gesso before gluing down the cradle. (This is because the primer is stickier than the gesso, so I have found that the clamps [or the protective strips] stick to the front of the panel and scar the surface if Kilz is the layer I clamp against; that also allows you to put down two more layers of gesso [at least] after the clamping is done, so any problems with the surface can be fixed.)

The best clamping situation I found was to set the panel face down on a flat table a little smaller than the panel (which would allow one to glue all for sides at once, if one had enough clamps; otherwise, any size table will work). I ripped and miter-cut strips of 3/4” birch plywood, then glued and clamped them with the plies at a right angle to the panel. (Lightweight clamps are best so that the panel doesn’t bend under their weight.) There are scrap pieces of 1/4” plywood protecting the face of the panel at each clamp (and in this case, also a bit of newsprint).

Since the sides were not otherwise joined to each other, when all sides have been glued and dried I drilled a hole in each corner for a dowel, in order to peg the corners together. A little glue went into the hole, the dowel was tapped in, and the remainder cut off. (Fine brads could also be driven in across the corners from both sides, but this sometimes involves sharp pounding against the brittle glue; also, if for some reason one needs to sand or trim the sides later, it is better to cut through wood than metal.) Any cracks can be filled with wood putty.

TWO EXPERIMENTS RELATED TO HOME-MADE PANELS

A. Correcting a Warped Panel. I wanted to see if I could correct those panels I have already painted and which have revealed warps and bows. One panel in particular (1/2” warped birch plywood to be straightened with 1” x 3” fir cradle) with an underpainting of saber-toothed cat skulls, had a bad bow. If straightening worked, I could finish the painting; if not, nothing was lost in trying. I sanded the back (which had been sealed with urethane) in order to have wood meet wood for gluing. While the sanding was irregular and, because of the awkward angle pressing a panel against our belt sander, the cradle tipped outward a bit, but it almost completely straightened the panel (at least for now). This makes me think I would try the same process on a couple of finished panels, but instead of sanding the backs, I would router a shallow rabbet to glue the cradle into.

Following up on the success of the saber-toothed cat panel, I used the router to shave a shallow rabbet (about the thickness of the face veneer) 3/4” of an inch all around the outer edge on the back of the T. rex with Parrot Tulip panel, a panel so warped that one corner pulled away from the wall when hung; it could not hang flat. I cut 1 3/4” strips of 3/4” birch plywood for a cradle, gluing and clamping it with the plies perpendicular to the panel, and mitering the corners. It was nearly a complete success,

with only the tiniest bow on one side. With the new cradle, this 3’ x 4’ panel weighed about 19 pounds.

B. Golden Sandable Hard Gesso. The Golden acrylic company has a new

product designed for rigid panels that takes sanding better than traditional acrylic gesso. It harkens back to the REAL traditional gesso, which was made with rabbit skin glue and a white like marble dust, gypsum, bone, calcium carbonate, or the like. Rabbitskin glue is water-soluble, so the acrylic version improves on that. The many layers of rabbitskin-based gesso were brittle, and this is apparently somewhat the case for this new gesso, as it is recommended for rigid supports only, to avoid cracking. Its advantage over regular acrylic gesso seems to be that it sands more easily (which the old gesso did, too, but this product would be much more convenient. That would be good, since getting a panel truly flat and without brush marks takes forever with regular gesso. (ALSO SEE COMMERCIALLY AVAILABLE PANELS, A. Ampersand)

In addition to the Ampersand panel, I have also used the hard sandable gesso on one of the LusterBoard panels, c. 18” x 24”, since these panels begin with a flat aluminum surface and the plywood core keeps the panel rigid. I hope I end up not liking to paint on such a surface because it is a real pain. The panel began with a layer of the Sherwin Williams DTM Bonding Primer, then three layers of acrylic gesso rolled on, then six layers of the hard sandable gesso brushed on. I began sanding with a 60 grit paper and found so many irregularities that I went back and squeegied two more layers on, to try to get them flatter. After beginning sanding again, I had to re-hit some areas where there were flaws. Then I went outside with a respirator and worked through layers with 60, 100, 220, 320, 400, and finally 600 grit with a sanding block. (The gesso really gums up sand paper.) When I finished, that panel felt like a Formica kitchen counter. There were still some imperfections, but the biggest problems were on the edges: Cutting the panel probably bent the aluminum slightly forward, so as I sanded, a shiny metal edge began to appear. That edge may also be why there were more flaws in the gesso near the edges. Then when I got to the 600 grit, the paper seemed to be picking up a little of the aluminum and making metallic streaks on the panel (which, after all, was now about the right surface for a metalpoint drawing). A frame should cover the edges, toning will obscure the streaks, and the scratches are to be expected in an early panel, but the whole process was so tedious and time consuming that it would be a shame if I end up liking the result.

As with the Ampersand panel, toning on such a smooth surface wipes off easily, so I toned it more than once.

*PROVISO Of course any panel material will involve compromises because every material has its drawbacks. While I am enamored of plywood as a surface, it has some problems: “It is known by many that wood, cardboard, adhesives, and other packaging and crating materials off-gas acidic vapors (formic acid, acetic acid, and aldehydes), which deteriorate stored items. Even very dry wood is problematic, and plywood is worse

because of the formaldehyde binding agent in adhesives.” www.interceptshrinkfilm.com (Intercept Technology, selling barriers for archival storage.) This is an issue raised by Ralph Mayer in The Artist’s Handbook, the materials Bible for artists. A solution in Mayer is echoed by The Society of Tempera Painters (www.eggtempera.com/supports.html ) “Wood may also emit acidic gasses and it is recommended that the wood be primed with a glue and calcium carbonate ground to insulate the paint layer from acidic vapors.” Further, that society has another complaint about plywood, as well as a suggested solution: “Plywood…Though stable against warping and splitting, this material has a surface grain which is subject to raising which may cause fine cracking throughout the gesso. Many plywood panels are made from pine or fir which contain resin that prevents the gesso from adhering properly but those made from birch plywood are more suitable.

“ Like all wood panels, plywood panels absorb and give moisture with resulting expansion and contraction. The movement occurs in every direction with plywood and there are numerous examples of paintings on plywood and virtually every one of them have eventually cracked. Early egg tempera painters reduced this risk by embedding a layer of thin fabric in their gesso ground and it does work. If you are using plywood or wood panels, apply an old well washed bed sheet to the panel first either with glue size or embedded in the first layer of glue gesso.”

The good news is that tempera painters are very sensitive to any movement in their supports, since tempera paint is quite brittle. Using an acrylic gesso (which is relatively flexible) should help, as does the fact that oil is somewhat more flexible than tempera. In regard to the acidic off-gassing, there are some products advertised as blocks for this: “Safecoat Safe Seal is a multi-use, waterbased, low gloss sealer for highly porous surfaces such as particle board, plywood, processed wood and porous concrete. Used primarily to reduce toxic outgassing: in particular, it is highly effective at sealing in formaldehyde outgassing from processed wood such as plywood, particle board and pressed wood. Safecoat Safe Seal is virtually odorless on application and odorless once cured.” (Product Description, American Formulating and Manufacturing, 3251 Third Avenue, San Diego, CA 92103; 619-239-0321; www.greenbuildingsupply.com/utility/showProduct/?objectID=377) Finally, there is this: “All wood species contain water-soluble materials (extractives) in varying amounts, which can create a staining problem when water-based light-colored finishes are applied to the bare wood. Western red cedar and redwood are two species most generally associated with extractive staining problems, but other species can also create them.” Solutions: Either use “a latex primer with an extractive-inhibiting ingredient,” or use a solvent-based primer. (American Plywood Association Technical Note Number J305 Finishing Sanded Plywood, January 1984.) That is the reason I use Kilz primer on my panels. I use the acrylic version because it should bond better with the acrylic gesso. So far as the primer/sealer/gesso layers go, I use two thin layers of the Safecoat Safe Seal applied to the front with a brush with a light sanding, since tiny fibers of wood raised up from the surface are made rigid by the sealer; the sides and back can have a single coat. I then use three layers of the Kilz primer (the acrylic version) and three layers of gesso applied with a roller for smooth surfaces for the front. (The back can have a layer of Kilz and/or gesso to balance the pull on the panel.) I use Daniel Smith

acrylic gesso because it is a good viscosity right out of the can for using with a roller. Some sanding between layers doesn’t hurt, especially if any small bumps appear from particles getting stuck in the gesso. The final layer should be sanded if a roller is used because the pebbly surface includes little peaks that are fragile; if they are painted over, but snap off later, tiny white spots appear in the painting. How much one sands is up to the individual, but if you want a really smooth surface, use a rigid panel and the Golden Sandable Hard Gesso mentioned above.

ALTERNATIVES TO PLYWOOD PANELS Descriptions are generally from the producers/distributors, though I have edited them some; my comments are in brackets. 1. Aluminum panels: A. Coated sheets of aluminum. Available in a wide variety of colors and sizes. Most painted sheets are color one side, white on the reverse side. Brite white sheets are painted with an acrylic paint while all other colors use a polyester paint. Alloy 3003/H14 http://www.harborsales.net/index.cfm [This would need some kind of backing, and it might make more sense just to buy aluminum panels with backing or a core, as below.] c. $17 for 36” x 48” @ .024 thickness* c. $46 for 36” x 48” @ .080 thickness* B. Dibond is “an aluminum composite material (ACM) made of two pre-painted sheets of .012" aluminum with a solid polyethylene core.” According to Alcan Composites USA Inc., its manufacturer, Dibond is “the flattest panel on the market”, is “approximately one half the weight of aluminum,” and even “provides excellent durability in outdoor applications.” It is available in thicknesses of 2mm, 3mm and 4mm; it comes in sheets of 4 ft. x 8 ft. and 4 ft. x 10 ft. [It looks very promising so far as maintaining a flat surface goes, but large panels would probably bow with their own weight somewhat. A frame should keep them flat. A bigger concern is how to make an aluminum surface receptive to paint. I have heard the following on those lines:] To make a paintable surface on the Dibond, here is input from the Golden Paints technical support staff: "We are very familiar with Dibond and have successfully worked with a lot of artists who have used it at this point. We have usually recommended Sherwin Williams' DTM Bonding Primer, which is engineered specifically for the type of baked-polyester finish Dibond comes with. After a suitable coat of a primer then you can simply continue on with the rest of our products." [Golden only makes acrylic paints, but that includes gesso, so anything normally painted on an acrylic gesso -- like acrylic or oil -- can be used.] [More Dibond information and sources] Dibond Impact & Fire Resistance - Dibond does not break like glass, asbestos panels or

other brittle products. It is resistant to blows and pressure and has a high buckling and breaking strength. Dibond has good fire resistant and can conform to a Class 'O' rating (BS 476) when the panels are framed.

Dibond Lightweight - Extremely light, Dibond - 2mm thick has a specific weight of 2.9kg/square meter compared with 4.6kg/square meter for aluminium sheet 1.7mm thick.

Dibond Rigid, Optically Flat Panels - Dibond panels consist of a core of low density polyethylene machine-bonded between two outer skins of aluminium. This balanced sandwich construction produces a very rigid yet optically-flat panel.

Dibond Weatherproof - Dibond has been used in applications where it is exposed to maritime and severe industrial atmospheres and used to strong sunlight. Consistent with the surface finish selected, it is highly resistant to the effects of such environmental conditions.

Dibond Good Temperature & Sound Resistance - Dibond absorbs vibration and has a low resonance response. The average airborne sound transmission loss of Dibond is approximately 21 decibels and as such is comparable with a 20mm thick plaster board or a heavy inside door. Temperature resistance ranges from minus 50°C to plus 80°C (-55°F to +176°F).

Dibond Easily Cleaned - Water and a sponge or soft brush are all that is required to clean Dibond. In cases of more severe contamination, alkali-free cleansing detergents may be added to the water.

Dibond Fabrication - Dibond panels can be cut to size by sawing or shearing; more complicated shapes can be produced using a jig or band saw. Reverse side routing to produce a V groove enables Dibond to be folded into a whole range of shapes. A more detailed Dibond fabrication guide is available.

$150.20 for 2mm 4’ x 8’ white/white www.professionalplastics.com/DIBONDSHEET www.averyvinyl.com/cgi-bin/store/store.cgi?&shop=alp&L=eng&Category=6001-E store.foamboardsource.com/medium---heavy-duty-board--dibond.html 2mm 4’x 8’ white both side, five sheets $1,303.25; 3mm 4’x 8’ white both side, five sheets $1,477.75 (ALSO SEE COMMERCIALLY AVAILABLE PANELS G. New Traditions Art Panels) [Best price: $114.36 4mm 4’ x 8’ w/w. This price is interesting: The trick is to find a

distributor. When I first went to the Harbor site, I found the shipping more than doubled the cost. (For one sheet of Dibond, 4’ x 8’ x 4mm @ $114.36, and one sheet of Lusterboard, 4’ x 8’ x 1/4” @105.36 from Harbor, the cost was $219.72, but the shipping and handling for this is $250.88 (and tax of $9.89), which more than doubles the apparent price.) Then I contacted a sign shop that sells Dibond and was willing to sell me a 3’ x 4’ panel for $325! I got in touch with Harbor, and they said they had a truck going through my town in Virginia, and that would be no shipping charge. That comes to:

c. $42.75 for a 36” x 48” sheet of 4mm Dibond, white/white. (For LusterBoard, see below.)] http://www.harborsales.net/index.cfm

C. LusterBoard's hardwood core is a premium grade, rigid, exterior furniture-grade plywood with smooth, tight, sanded veneers for optimum surface beauty. LusterBoard panels have two finished, white (or painted color) aluminum surfaces. http://www.harborsales.net/index.cfm

c. $40 for 36” x 48” D. Alumalite is a strong, aluminum composite panel with a high-density, corrugated polyallomer (CPA) core that will not swell, wick water, corrode, rot, or delaminate due to prolonged water exposure. The surface is .016-inch high-gloss painted aluminum. An aluminum surface is required on both sides for rigidity and to minimize warping. Alumalite features a factory baked acrylic-painted aluminum faces for high gloss brilliance and is warranted not to crack, chip, flake or peel. http://www.harborsales.net/index.cfm c. $37.50 for 36” x 48”* E. D-Lite™ has a finished aluminum surface that won’t crack, chip, flake or peel ... and a water insensitive, plastic core, making it perfect for your outdoor or UV- exposed indoor applications. The core is a high-density, corrugated polyallomer (CPA), that will not swell, wick water, corrode, rot or delaminate. The finished surface is .012-inch, high-gloss white aluminum on two sides, or with a light gauge aluminum backer. An aluminum surface is bonded to both sides to balance the board and maximize flatness. http://www.harborsales.net/index.cfm c. $37.50 for 36” x 48”* 2. Canvas

A. Utrecht 66J “ultra-smooth” single weave linen canvas. [Traditionally artists have worked on canvas, especially for large paintings when the weight of a panel would be prohibitive. Linen is the strongest and longest-lasting traditional artist’s canvas. Not only does it seem that the larger the panel, the heavier it gets and the more likely it is to go out of flat, but also if I want to create a very large image -- one that is over 4’ in both directions, 4’ being the widest panels commonly come -- I will need to work on linen.

Linen has some disadvantages, though, especially for the way I work. First, even the “ultra smooth” linen has a texture, and glazes tend puddle in low areas; since glazes are transparent, these areas come off as darker. Second, because linen is not a rigid surface, one cannot bear down on the surface when making a transfer, or rest a hand on the surface when doing detail work. The texture also hampers both of these. (The rigidity problem can be overcome on a small scale by using linen mounted on panel, but that is obviously not a solution when it comes to large scale, nor does it solve the texture problem for me.)

(Art Panel, Inc. offers linen-covered panels up to 54” x 120”, since they use a composite panel like MDF which they can get up to 5’ x 10’.)

I have undertaken a portrait on a small scale with this linen to see it my technique will not be too greatly impeded, and it worked just fine.]

c. $74 for 36” x 48” canvas using Dick Blick (the cheapest vendor for these)

heavy duty stretcher bars and one cross brace (c. $32) and 42” x 54” piece of Utrecht 66J linen (c. $42). (www.utrechtart.com) (www.dickblick.com) 3. Gatorfoam. Gatorfoam panels are a lightweight, man-made wood-polystyrene product that has an inert acidic content of 6.5~7.0 pH—inert meaning they will not become more acidic over time. They are less acidic than hardboard. The panels are waterproof and handle all types of weather with ease. Whether you’re in rain, snow, or in the heat, the panels hold up quite well. The standard panel is 3/16” thick or a 1/2” panel is used for sizes 18”x24” and above. Further, Gatorfoam foam board is an extruded polystyrene foam board bonded between two layers of Luxcell wood-fiber veneer. New, bright white facer is the brightest foam board of its kind and good for digital and screenprinting. Offers 5' x 10' large format capabilities. 3/16”, 1/2”, 3/4”, 1”, 1 1/2”, 2” thicknesses. [While I saw this advertised in one source as a great product for artists, after research it became apparent that this is just a fancy form of FoamCor Board, used for mounting displays and lightweight signs, but not really a substantial painting support.] 4. Hardboard, or HDF (High Density Fiberboard, ex. Masonite) According to the Ampersand website (www.ampersandart.com), “in the 40’s and 50’s, tempered hardboard was made by immersing the panels in dipping tanks of tung or linseed oil to harden them, leaving an oily residue that caused adhesion problems for artists. Untempered boards also had problems with chipping and fraying, which made conservators leery of paintings done on these now outdated hardboards. Over 20 years ago, the high cost of tung and linseed oil forced U.S. manufacturers to change the way they manufacture hardboard. Today’s U.S. hardboard is made differently and does not have the characteristics of the old hardboard.” [I have experienced the chipping and fraying, as well as some adhesion problems. Apparently Ampersand has avoided much of this by using an improved hardboard, which employs hardwood fiber and avoids the excess use of tung oil. This may be the case, but I am a little wary of the product, and since not all producers maintain the same high standard of Ampersand’s source, hardboards are not all the same. Unfortunately, it appears Ampersand does not offer panels larger than about 30”.] Ampersand also includes the following on their site: “All wood surfaces should be sealed with a good primer before gessoing or painting on them. Unlike hardboard that has been processed and reconstructed, plywood and other solid wood panels still have their cell structure intact

and the harmful lignins and wood tannins could affect a painting if not sealed correctly. Ampersand recommends using Golden’s Acrylic GAC 100 to seal panels for water-based painting and the Gamblin's Oil Painting Ground for use with oil paints. Ampersand’s Hardbord™ can be primed using these products or try one of the already sealed and coated panels.” 5. Medium Density Fiberboard (MDF) is a dry-process type fiberboard panel with a density below that of HDF and hardboard. This lower density makes MDF the most warp-resistant wood panel available. Unlike the very dense hardboard fiberboards, fibers in MDF panels have the necessary room within the internal structure of the board to expand (from moisture or heat) without distorting the panel. [?] While this lower density gives MDF somewhat less structural strength than other fiber boards, it is still very hard and strong, and more than adequate in that regard for use as an artist panel, for which it is very well suited. MDF and HDF are very similar panels and share most of the same qualities; they tend to differ only by a small amount in density. The manufacturing process of these products usually results in the thinner panels having slightly higher densities. Panels of a half inch or more are generally MDF; panels of a quarter inch or less usually fall into the category of HDF, though these are generally called "thin MDF" (TMDF) since the public is more familiar with the term "MDF' than "HDF'. [Despite the praise of MDF above, offered by a company offering panels made if it, I am skeptical. Sandy (my wife) worked with MDF and acquired asthma from cutting the board. It swelled when wet, and wasn’t that strong when looking at thin sheets (c. 1/2”) of any moderate size. Corners crumble, too. The panels this producer makes are sealed with urethane, with a baked-on white urethane primer/ground, which is unusual. Larger panels involve an MDF/balsa wood/MDF sandwichboard with an unusual construction: end-grain balsa.] “Balsa wood timbers are sliced like bread; then the slices are laid edge-to-edge to form sheets. In this configuration, the wood fibers align to form a natural ‘micro-honeycomb’ structure. Panels made with these balsa cores can be sealed very effectively, since none of the end grain of the wood is exposed on the edges of the panel.” (SEE COMMERCIALLY AVAILABLE PANELS, B. HUDSON HIGHLAND www.hudsonhighland.com) 6. Medium Density Overlay (MDO) Plywood. [I received a PDF file from the information officer at the American Plywood Association telling about a plywood product that has an overlay of medium density fiberboard (sort of like Masonite or hardboard) and is supposedly used by sign painters.

According to the PDF, the MDO surface may be specified on the face only or on the face and the back. This is important because a sign painter might paint on both sides and keep the panel rigid with a frame around the edge; I would be looking to paint on one side and adhere a cradle to the back. When I have glued cradles to medium density fiberboard in the past, the glue sticks the cradle to the fibers on the surface of the panel, but those fibers are not tightly bound to the panel; a sharp shock to the panel can separate those fibers from the panel (delamination), and the cradle comes off. If, however, one

can get the MDO on the face only, the back will be a plywood surface that should hold the cradle.

Its other advantages may include that the surface would be smooth, with no grain, but designed to take paint, and that the corners might be less apt to splinter (like a hardwood veneer can) or crumble (like a fiberboard can). An email I sent to a professional sign painter said that this stuff is all there is for sign painters (which I take it is an endorsement).

I later ran into a website (www.hudsonhighland.com) hosted by a company which sells artists panels and which has opinions about various potential panel materials. MDO’s “resin-treated fiber overlay” (as the PDF described it) is dismissed by the Hudson Highland site as being “usually made of plywood, coated with outer layers of resin-impregnated Kraft paper…Because of the impermanent nature of the Kraft papers used, MDO is not considered a suitable material for use in permanent artworks.” This may be very good advice, though the Hudson site has no sources indicated in its extensive commentary,] 7. Plastics

A. ABS panel. Acrylonitrile butadiene styrene, or ABS, is a common thermoplastic. (SEE COMMERCIALLY AVAILABLE PANELS C. Realgesso www.realgesso.com)

B. Acrylic sheets. Produced from a methyl methacrylate monomer and have outstanding physical, mechanical, optical, chemical resistant, and thermal properties. G Grade (cast acrylic) material provides UV light absorbing properties for outdoor exposure, and excellent machining properties. (http://www.harborsales.net/index.cfm [The preceding quote is from Harbor. A chemist friend says “no” to this material: Ammonia and others solvents begin to cloud and soften it, and it cracks easily.] c. $45 for 36” x 48” @ 1/4”

C. Makrolon Polycarbonate A polycarbonate sheet that is 30 times stronger than acrylic, and is great for use in high traffic areas where breakage is a concern. Maintains its impact strength at low temperatures and can be fabricated using a variety of woodworking tools. (http://www.harborsales.net/index.cfm [The preceding quote is from Harbor. A chemist friend says this material has problems with chemical bases]

D. Polyvinyl polymer panels: [The length of this entry does not imply an endorsement; I felt that since this is non-traditional surface being marketed specifically for artists, I would include the maker’s extensive description.] Solid Ground™ panels are hand crafted, made-to-order art panels, available in versions for painting or pastel. They differ markedly from older panels, both in materials and basic structure. Unlike traditional paint or pastel supports, they are made entirely of durable and stable polyvinyl polymer resins, blended with fine quality pigments. Solid Ground™ panels, as their name suggests, are not coated or layered in any way. Rather, each panel is made as one

solid piece. Rigid and self-supporting, they consist of solid ground through and through. Support and ground are one. No priming is necessary. Color is applied directly to the support, giving your artwork an inherently sound and fundamentally simpler foundation.

Solid Ground™ panels are exceptionally durable. They are nonporous and waterproof. And although they have a feeling of absorbency (as color is drawn tightly into the micro-texture of their surfaces), they are non-absorbent, and were designed that way for several reasons. Solid Ground™ panels are uniquely designed to address problems of acidity. Deterioration of artworks can often be traced to acidic contents in artist materials. Solid Ground™ panels, by virtue of being non acidic, non-absorbent and free of layers, eliminate these problems completely. Unaffected by moisture, Solid Ground™ panels do not expand and contract with changes in humidity. They have superior dimensional stability. They are extremely resistant to warpage, swelling, splitting, and embrittlement. Solid Ground™ panels are chemically stable as well. They exhibit no chemical off-gassing. They are nonacidic and are internally buffered (with calcium carbonate as one of their pigments) to keep them that way. They are unaffected by weak and moderate acids and bases, as well as by all standard art studio solvents. Polyvinyl resins have properties which make them particularly well suited for use in art panels. While they are not chemically reactive, they are extremely chemically receptive to artist colors. The molecular structure of polyvinyl polymers makes paint and pastels want to stick to them. [?]...

Polyvinyl resins also give Solid Ground™ panels a perfect surface hardness; they are quite strong, but are still malleable enough to be able to accept the abrasive finishing procedures which are used to give them their uniquely receptive surface textures. Many familiar household products made from polyvinyl plastic are easily damaged by UV radiation, and by internal degradation caused by the presence of chemical plasticizers. Solid Ground™ on the other hand, contains only plastic which is extremely durable and stable. By design, Solid Ground™ panels contain an exceptionally high concentration of Titanium Dioxide. This very effectively shields them from UV exposure, giving them excellent lightfastness properties and preventing UV damage to the polymers. (Lightfastness of the pastel panels differs somewhat by color; please inquire for details.) Solid Ground™ also contains no chemical plasticizers, since these materials can also degrade and migrate out of the plastics, and make them sticky or brittle, we've taken care to avoid their use altogether. Solid Ground™ Surface Properties...While intermolecular attraction plays a role in paint-to-panel adhesion, an actual physical grip, or "mechanical bonding,” is the most important factor in the bonding of color to Solid Ground™. From the smoothest grade of Artist Panel to the coarsest grade Pastel Panel, the panel surface is actually a dense, complex network of tiny fissures. Although sometimes almost imperceptibly small, these fissures can be seen as quite sharp and deep when viewed under magnification. Colors are drawn into this matrix and held fast. The panel surfaces also have a fine, fibrous nap, with tiny silk-like fibers protruding from them. These fibers become imbedded in the color layer, further reinforcing its bond with the panel.

Plastic, as a painting surface for artists, has quite a track record. Artists have been painting on plastic surfaces for half a century. In fact, for many decades now, the large majority of paintings made by artists have been painted on acrylic gesso. Polymer gesso coatings have generally held up very well over the decades, although they are not the

ideal primer in all situations. They can often be rather permeable, allowing oil to soak through to the canvas. And depending on how they are formulated, applied, and prepared, they can often be rather slippery and provide a less-than-ideal bonding surface for some paints. Plastic panels are physically strong. They eliminate the dangers of "delamination" – the eventual separation or chipping away of the primer from its support.

Although the easiest and neatest way to get Solid Ground panels in the exact sizes that you want is simply to order them that way, it is not difficult to cut them yourself. Most any kind of power saw can give very good results. Radial-type saws (table saws, radial arm saws, miter saws) work best, but jig saws and band saws work fine as well. Use a relatively fine-toothed blade (types made for plywood are usually about right). A circular "hollow-ground" plywood blade is ideal if you can find it. Using a blade with teeth that are too big (or too few) will give a chipped edge. Teeth that are too fine (like a blade made for metal) will tend to burn or melt the edge, as will too slow forward progress of the cut. However you do the cutting, always start by taping a piece of corrugated cardboard (cut to the same size as the panel) over the face of the panel to protect it from scratches and abuse. When cutting, cut through the panel and the cardboard at the same time. After cutting, you can clean up the edges nicely with sand paper. Like virtually any material, Solid Ground panels will expand and contract with changes in temperature, and the greater the temperature change and the larger the overall size, the greater will be the total size change. The rate of change is similar to most hardwoods (actually just a slight bit less). Unlike wood, the change is almost even across the length and width as there is no significant "grain" to the panel. When framing a very large panel, potential differences in the expansion / contraction rates of the panel and the framing material should be taken into consideration, and adequate leeway should be given, especially where the installation may be subject to significant temperature fluctuations. Solid Ground panels do not expand and contract with changes in humidity, as wood does, but extensive swelling of a wooden frame due to humidity could still apply unwanted stress.

Mounting and Bracing Solid GroundTM Panels: Although quite rigid, they are not completely so; a certain degree of flexibility (more evident in 1/4"panels and in larger sizes) actually gives them the adaptability and "memory" to remain flat, or to return to a flat condition after the stresses are relieved. From the panelmakers [sic] point of view (or a conservator's) we would like to see the panels supported by nothing more than a strong picture frame. In the real world, of course, this is often unrealistic. Mounting / bracing usually involves gluing wooden strips to the rear of the panels, although other possibilities involve using aluminum or plastic bracing, or mounting our panels on to wood or plastic sheets (size and weight allowing). Since the backs of the panels are generally quite slick, it will be necessary to roughen the backs with sandpaper at the points of contact in order to achieve a sufficient grip for the adhesive to gain a good bond. Adhesives used for bonding must be flexible. Since the panel and the materials used to brace it will likely have different rates of expansion and contraction, any adhesive that is brittle upon drying will likely pop off of the panel or the brace. Adhesives which dry to a flexible consistency allow for differences in dimensional changes, and allow the panels and bracing materials to slide against each other if subjected to slight flexure.

Adhesive caulking materials. Two types that work are pure silicone caulking, and siliconized acrylic latex caulking. These usually come in the form of caulking tubes and can be purchased at a hardware store (G. E. 100% Silicone Caulking and Alec Acrylic Latex Caulk With Silicone are two common brands; Elmer’s Squeeze-N-Caulk is an acrylic latex that comes in a regular glue-type bottle). The Siliconized Acrylics give a stronger bond and many can be painted over. Pure Silicone types give a weaker bond that is, however, more easily reversible. Silicone has the advantage of being very neat in that any overgluing can be cleaned easily by simply rubbing it off Wood is the most commonly used bracing material. For an extremely durable method, two of my customers have had great results using square (or rectangular) aluminum tubing to brace the panels. Drilling conical shaped holes through the mounting material before it is glued on (such that the narrower end of the hole points toward the wall) provides a hole with a small lip to catch a nail or screw head. When bracing the edges of the panel for hanging purposes, putting the hang-holes in the vertical braces rather than the top horizontal brace distributes the weight and stress better. (SEE COMMERCIALLY AVAILABLE PANELS, B. HUDSON HIGHLAND www.hudsonhighland.com)

$138.24 for 36” x 48” panel

E. Rigid High Density Urethane Foam. A rigid high density urethane (Signfoam3) material which is not affected by solvents, can be finished using all sign paints including lacquers, is completely waterproof, and can be fabricated with standard woodworking tools. (http://www.harborsales.net/index.cfm This quote is from Harbor.] c. $65 for 36” x 48” @ 1/2” COMMERCIALLY AVAILABLE PANELS There are some good commercial producers of panels out there, most based on high-grade plywood faces. A few of these places are made-to-order, so there is some lead-time required. I have tried to get a price for a standard size panel (36” x 48” cradled) for comparison, though it must be kept in mind this does not include shipping. Descriptions are generally from the company, though I have edited them some; my observations are in brackets. Just looking at their products gives me ideas about how to design my own, and the price comparison (all well over $100) is an incentive to build my own. A. Ampersand www.ampersandart.com Hardboard is the finest pressed wood panel available anywhere. Made in the U.S.

from quality hardwoods, this panel resists warping and moisture penetration. Hardboard accepts all types of commercial and handmade gesso grounds. Complete priming instructions inside product labeling. Available 1/8" flat, 1/4" flat, cradled with 3/4" strips or with the new 2" DEEP cradle. [These panels seem not to go very large, perhaps no more than 24” x 36” or 30” x30”. They also have something called “Gessoboard,” which is the hardboard with an acrylic gesso. The 3/4” or 2” cradles with birch plywood run the plies vertically, at a right angle to the picture plane. I bought an 8” x 10” unfinished panel with the 2” deep cradle to check on the construction. The plywood of the cradle has even plies and looks like it alone would make a good painting surface. When I sealed the hardboard with a layer of Safe Seal, it sat mostly on the surface, indicating the presence of some water-repellant binder or sealer. Next came three layers of Kilz, then three of acrylic gesso and about six of hard sandable gesso using a foam brush. I decided to use the sandable gesso for several reasons: This panel is small and very rigid (the sandable gesso requires a rigid surface), the hardboard is quite smooth (which should help on sanding to a smooth surface), and since it is small, it will take less effort to get down to a truly smooth ground.

I sanded the panel down to 400-grit emery, and while there were still some scratches visible in a strong raking light, the surface was as smooth as plastic. Toning it was tricky because the toning tended to wipe off (and the scratches showed some), but I decided to do more than one toning.] B. Art Boards www.art-boards.com

[They have several products, the most interesting to me being cradled maple veneer plywood panels. They use 1/2” plywood with 5 plies. Three internal plies are made of aspen, and the two faces are maple veneer, all held together with waterproof glue. The cradle is made from strips of the same plywood. [They work with excellent materials, which may reduce the problems, but the price (a 3’ x 4’ cradled panel is about $190) and the worry over damage in shipping make me want to make my own, if possible. I have to admit that it also seems curious to cradle 1/2” plywood with 1/2” plywood; I have found a 1/4” plywood panel apparently strong enough to pull a 3/4” plywood cradle out of true when the plys in the cradle are parallel to the panel, as is done here. Art Boards, Inc. also says they have some new materials which are very light, with balsa wood somewhere in the construction. It is nice to know that such things are out there, if you have the money. They additionally have something called a Natural Fiber Art Panel. This is a MDF board variation.] The Natural Fiber Art Panel is 3/8 thick. It has an ultra-smooth surface with no wood grain. It is made using a process that combines pure wood from Douglas Fir trees with urethane binders, producing a painting panel that is double refined with no oils or resins. Art Boards™ Natural Fiber Art Panel is NOT tempered Masonite or tempered hardboard. Custom Sizes Available Cradled and Uncradled as large as 60" x 120".

$190.00 price for 36” x 48” panel, 1/2” maple plywood (aspen core) with 1’2” maple plywood cradle (aspen core); Art Boards C. Hudson Highland www.hudsonhighland.com

1. $138.24 price for 36” x 48”. “Solid Ground” Polyvinyl resins panel, no cradle; Hudson Highland.

2. Primewood Panels Prices not currently available on the site.

D. John Annesley Company www.johnannesley.com/CradledPanels.html All of our cradled panels have 3-ply faces. The first two layers are mahogany, the top face is your choice of birch or mahogany. Each birch face painting panel is spliced using the bookend match technique. Birch is considered to be a very seductive surface to paint on with its very tight grain and swirly grain patterns. Each mahogany face painting panel is from rotary cut, endless core wood, that means it's a continuous piece with no splices. Mahogany is an open grain, insect resistant wood, that provides a bit of texture to capture the paint. Our standard cradled panel thicknesses are: 5/8", 7/8", 1-7/8", 2-5/8" Available in any dimension, tiny to huge! Uses basswood for cradle. [I contacted John and found that, as I suspected, their truly large panels -- those over the standard size for plywood sheets) are pieced. He indicates the piecing is visible but cannot be felt; still, his recommendation for these larger panels is to stretch canvas over them.] $176.26 for 36” x 48” Thin Wraparound Panels, (P3) 1-7/8" deep, with crossbrace in cradle. $221.01 for 36” x 48” Thick Panels, (P4) 2-5/8" deep E. New Traditions Art Panels www.newtraditionsartpanels.com/catalog/index.php

Baltic Birch Panels. We are now offering our linens mounted on 1/8” and 1/4” Baltic Birch. We seal the back of the panels with Polyurethane. This seals the wood from moisture and minimizes warping (wood still has the tendency to warp). [These seem to be linen panels. They also carry Dibond panels, though they, too, may be linen panels with Dibond supports. Further, they carry something calls “multimedia panels,” which sound like a glorified canvas board.] Multimedia Panels. Linens are available on multimedia non-buckle board. This product is a blend of paper pulp and thermal set resin that is acid free and neutral pH and will not yellow or deteriorate. This art board is versatile enough to be

painted upon with nearly any media. This board comes in only 1/32” thick, which makes them the panel of choice when traveling since they are extremely lightweight and easy to pack. Multi Media can be mounted on a backing board for framing. These are a custom item and not stocked in inventory. Multi media can also be painted on directly without linens. F. Pictors www.pictors.net Our beautiful panels are made using only the finest materials and methods. And please note that they are composed entirely of wood and glue. A significant component in our panels is the mortise and tenon joinery of the supports, in which a protruding piece of wood (tenon) on one joint end fits securely into a hole (mortise) on the other. This method produces one of the strongest joints used in woodworking. 1/4" Baltic Birch, aka ‘Russian Birch’, is a high-density plywood used for the face of our panels, chosen for its strength, durability, and resistance to warping. It is composed of five plies of flawless hardwood laminations, so it is free of voids in its internal layers, which makes it stronger and more warp-resistant than the average three plies seen in most other kinds of 1/4” plywood. Supports are constructed of kiln-dried Poplar and Douglas Fir, which were chosen for their strength-to-weight ratio, durability, and resistance to warping. Each piece is hand-selected for their straightness and appearance. Note: All wood is porous and can therefore be affected by seasonal changes and environmental variables. Pictors recommends all panels be properly sealed, prior to use, in order to resist against inevitable environmental factors that affect the structural stability and surface of wood products. $ 128.37 for 36” x 48” panel. G. RayMar Plein Aire Panels www.raymarart.com 1/8” hardboard, ph neutral adhesive, melamine (melamine is a resin, chemically C3H6N6) impregnated backing, covered with linen or cotton canvas. Sold in 10 packs (18” x 24” linen single prime is $238.28/ canvas is 99.28) Sample pack for $17. They sponsor a prized competition for realist images on their panels. [These also seem not to go large, the biggest I could find being 18” x 24”; they also are canvas and linen panels, not plain, flat panels.] We use Claessen's #15 100% Belgium linen exclusively for oil paint. The medium texture, medium weight linen is a favorite of professional artists for its irregular weave and 0% absorbency. It is suitable for portrait, landscape and modern work with brush or palette knife application.” Double Oil Primed Linen comes with an additional coating of titanium white for the artist seeking an ultra smooth surface. Single Oil Primed Linen is sized twice with a zinc white primer bound with linseed oil

and a top coating of titanium white oil paint. Cotton: Our smooth texture is a medium weight polyflax/cotton blend with an ultra smooth surface. It is triple acrylic primed for oil or acrylic paint. Creating minimal absorbency, this triple coating provides an ideal surface for portrait and fine detail painting. Our smooth texture canvas permits more paint manipulation and produces a translucent effect similar to oil primed linen. Medium weight canvas is 100% cotton duck with a uniform medium texture. It is coated with a double acrylic acid-free priming for oil or acrylic paint. Designed for landscape painting, the absorbent texture grabs the paint for an opaque effect and also works well with water-based oil paint. H. Realgesso www.realgesso.com For sizes above 24x36, please call for product shipping and price. 706-227-2921 [Hardboard panels, available with an interesting traditional cradle.] These hand-crafted art panels are made from a traditional gesso recipe specially formulated from crushed marble, rabbitskin glue and high- quality titanium pigments. Several thick coats of this gesso are applied to a dimensionally- stable 1/4" premium hardboard. Our precision- engineered "floating" cradle design provides the perfect support for both the Realgesso and ABS art panels. Using precise joinery and a unique method for adhering, these cradles prevents them from "telegraphing" their shape through the panel. The hardwood-backed ABS panel has the added feature of being laminated to dimensionally stable, furniture-grade, hardwood laminate. (Acrylonitrile butadiene styrene, or ABS, is a common thermoplastic.) I. Rodney Thompson custom panels www.rodneythompson.com/panels/panel_info.html

Prices are representative for 3/4" maple cradle with 1/4" Baltic birch panel up to 2” in depth. Maple panels (maple veneer on mdf core) also available for additional charge. Panels are made to order, so there is some lead-time. [They have an interesting bracing system from behind.] Standard cradle is plywood with vertical plies, but others are available.

The standard cradled panel is built with domestic, furniture grade, 3/4" white maple plywood, mitered for the cradle frame. The standard panel is a 1/4" Baltic Birch plywood panel with its distinctive 5-ply banding. Also available is 1/4" A-1 domestic maple veneer on an MDF core.

$150.00 for 36” x 48” for 3/4" maple cradle with 1/4" Baltic birch panel