m a g a z i n es preparation finishing tips€¦ · create your own sanding sticks for...

woodmagazine.com 1A Supplement to WOOD® Magazine

40 Solutions to sand, stain, and finish your projects

Proven methods by the editors of WOOD

WoodWOOD m a g a z i n e’ s

®

Preparation & Finishing Tips

Paste filler to the rescue p.5

Wood Preparation & Finishing Tips2

ContentsA Sampling of Solutions...

Blend light and dark areas evenly.

Create your own sanding sticks for hard-to-reach areas.

Prepare for a silky smooth finish surface.

Make furniture repairs disappear.

Catch contaminants before your project does.

Create a professional high-gloss finish.

WOOD® Magazine's Wood Preparation & Finishing Tips

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P.5 P.2

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©Copyright Meredith Corporation 2010. All rights reserved.

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Too late now—you’ll need to remove the finish and stain, and then restain the entire surface.

To avoid this blemish in the future, sand only after the second and successive coats. Finishes, such as lacquer, partially dissolve the previous coat and require no between-coat sanding. When applying polyurethane finishes, apply a second coat without sanding the first coat. Then, use 320-grit sandpaper on a handheld pad, as shown at right, to scuff-sand a bondable surface for the next coat. Commercial sanding sealers require espe-cially mild sanding.

CHALLENGE: Despite your best efforts to gently sand a finish, the abrasive cut through the topcoat and stain, leaving a light spot on the wood.

Edge-banding hardwood plywood with matching veneer often leaves overlaps where the edging protrudes above the plywood faces. Avoid the temptation to pick up your sander and lean it over to even out the excess. Too often, the plywood hardwood veneer disappears along with the edg-ing, exposing the layer beneath.

Time for a new strategy. Trim the veneer using a chisel, with the bevel side up and the back flat against the face of the plywood, as shown at right. Finish by lightly hand-sanding with 220-grit paper or higher.

CHALLENGE: You’ve successfully edge-banded a plywood tabletop, and proceeded to sand the banding flush with the plywood face. Then, disaster strikes. In the blink of an eye, you’ve sanded through the plywood veneer!

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Learn more wood-finishing techniques at: woodmagazine.com/finishes

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To reveal potential problem areas before you apply stain, next time wipe the workpiece with mineral spirits. This makes it easy to see areas of contrast that a stain may not even out. Then, apply a toner to the light areas to blend them with the darker ones. This process is often referred to as “blending.”

The three photos show the problem and how to solve it. The edge-glued cherry panel shown at left, for example, has an area of sapwood along one joint. Because sunlight darkens cherry, place the wood in direct sunlight for a couple of days to let it darken, and then match that color. (Sunlight doesn’t have the same effect on all hardwoods.)

Mask the area surrounding the light-colored wood and spray toner as shown at right. (To decide which toner or toners will do the trick, spray samples on glass beforehand.) Then remove the masking material and feather the toner into the rest of the surface. When you’re satisfied with the color match, let the toner dry. You might want to spray a light coat of toner over the entire piece to make the overall appearance as uniform as possible.

In most cases, you’ll want to spray on a clear topcoat after the toner dries. Spray-ing instead of brushing avoids disturbing the toner, which becomes a problem if you apply lacquer on top of lacquer toner, or shellac on top of shellac toner. A good topcoat allows you to rub out the finish without going through it and into the toner.

Solution 3

CHALLENGE: You thought the sapwood in a glue-up would blend with the surrounding wood when you applied stain. This made the light area stand out more!

Mask off the areas that don’t need color, either with tape or by holding a piece of cardboard where needed as shown above. Then, spray toner to the sapwood within the masked area. Check your progress frequently by moving the cardboard or lifting the tape.

The combination of two toners—honey maple followed by medium red mahogany—blended the sapwood in the panel at right. A light coat of honey maple sprayed over the entire tabletop evened out the overall appearance.

Stain often fails to even out the differences between boards of different colors, and can even emphasize them, like the light sapwood above.

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Sapwood

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Solution 4

Solution 5

Done right, power-sanding speeds your way to a silky surface. Done wrong, your impatience will haunt you with every flat spot, gouge, or burn mark your tools leave behind. A firm push to remove saw marks along the edges creates burned wood—especially true with maple, cherry, or walnut.

To avoid this problem, use a coarser sandpaper—such as 80 grit—on your disc or oscillating spindle sander. Let the machine do the work, and use light pressure when pushing the workpiece against the abrasive—especially on end grain. Keep your sander or the workpiece in constant motion to prevent heat buildup.

Oscillating spindle sanders, like that shown at right, work great for dense hardwoods. The up-and-down motion of the spindle spreads sanding-generated heat over a greater area than a sanding drum on a drill press, although you still need to keep your workpiece in motion.

If you’re sanding a workpiece to a pattern line, first cut it to within 1⁄16" of the final shape to eliminate as much power-sanding as possible.

When you’ve smoothed the surface with an 80-grit drum, you then can step through the 120- to 220-grit drums with-out fear of burning the wood.

CHALLENGE: Every time you sand hardwood with a drum sander, the 220-grit paper burns the wood. Not pretty!

When you combine a fine-grit sanding drum and excessive pressure, there’s a good chance you’ll burn the wood.

Customizedsanding block

Burnt edge

A small-diameter sanding drum may produce a series of bumps and dips that are a challenge to remove. To prevent this, always use the largest-diameter drum that fits within the radius of the curved edge. An alternative to drum-sanding uses the curved cutoff from the workpiece. Rough-sand the saw marks from the curved edge of the cutoff without altering its profile. Then, cut and attach strips of adhesive-backed sandpaper in progressively finer grits, starting with 60 grit and ending with 180 or 220 grit, turning the cutoff into a custom-contoured sanding block.

CHALLENGE: You thought your sanding drum would smooth a gentle bandsawn curve. But to your fingers, the curve now feels like an Olympic mogul course.

On a sweeping curve, a small-diameter sanding drum may produce a series of ripples.

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Solution 6

Solution 7

Enlarged sanding area

CHALLENGE: You used a random-orbit sander to smooth an uneven joint in a panel. Now, it’s worse: You created a big dip.

Portable sanders make poor thicknessing tools—especially belt sanders and random-orbit sanders. When gluing up boards, inspect for misalignment and slips at joint lines, and realign the pieces quickly before the glue sets. If a problem still surfaces, visualize an area about twice the width of your sanding pad on either side of the joint, and work gradually from the edges to the center to avoid abrupt surface changes directly over the joint.

CHALLENGE: When you applied stain to a project, all sorts of sanding sins reared their ugly heads.

Next time, wipe down all the surfaces you plan to sand with a tack cloth to remove sawdust and other debris that can make deep scratches when they are picked up by the sander. Then, progressively move through the sandpaper grits from coarse to fine and let the sander do the work, wiping down the piece with a tack cloth between each grit change.

Next, using a soft cloth, apply mineral spirits to all sanded areas. The “mineral spirits rubdown,” shown below, offers three benefits: It gives you an idea of what the wood will look like with a clear finish, reveals glue stains you may have missed, and highlights any remaining tool marks, including notoriously hard-to-see sanding marks and swirls. Take note of the spots that need more work, and go back to them after the mineral spirits dries.

Use this trick before assembly or during dry-fitting to find problems that would be difficult to repair after glue-up.

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Chatter marks

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Solution 8

CHALLENGE: That nasty ding on the dining room table bothered you for weeks. When you tried to fix it, the patch looked worse than the original damage because the patch didn’t match.

The porous texture of some wood putties makes them soak up more stain than the surrounding wood.

To avoid excess stain both in and around the patch, cover the putty with a light coat of shellac before attempting a color match.

A graining pen helps you reproduce grain lines that mimic wood. A fine-bristle brush and dark pigments produce a similar look.

Pigment samples sealed with clear shipping tape make it easier to determine the colors needed to match surrounding wood.

Expert furniture finishers and restorers know how to make their repairs disappear within the grain and color of surrounding wood. Equipped with the techniques pre-sented here, and a little practice, you can master this skill too.

Start by restoring a flat surface using a wood patch. Any solid filler material that bonds with the wood and flexes as it shrinks and swells will work. Patches can be made from ingredients as simple as sawdust mixed with wood glue or as sophisticated as wax burn-in sticks used by professionals.

Common store-bought wood fillers include acrylic-based products that clean up with water before drying; gypsum-based products often sold in powder form, giving them a long shelf life; and nitrocel-lulose-based putties that cure quickly. All three perform well for general woodwork-ing repairs using the cover-up techniques explained here.

Whichever type you choose, don’t assume that “stainable” equals “match-ing.” These patching compounds will likely absorb more or less stain than the sur-rounding wood.

The patch-hiding technique here works on unfinished and finished projects using earth-tone pigments to conceal patched areas. An assortment of 11 earth-tone powders (item #53Z04.21, $28.50) from Lee Valley Tools (leevalley.com or 800-

871-8158) includes every color you need except white. You can find white pigment at art supply stores, which sometime sell earth-tone colors as fresco powders.

Professional refinisher Alan Noel uses pigments from the Furniture Doctor, furnituredoctor.net, they offer a touch-up kit with seven 1-ounce jars of white, black, and earth-tone pigment powders, plus a graining pen and five touch-up sticks, all for about $65, plus shipping. You’ll also need a fine-tip sable brush, a piece of glass roughly 6" square (for drying samples of color), dewaxed blond shellac mixed to a 1-pound cut or thinner, denatured alcohol for use as a shellac thinner and brush cleaner, sandpaper in 220 and 320 grits, a putty knife, crafts knife, and painter’s (blue) masking tape.

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Many, if not most, home woodworkers rely on a brush rather than a spray gun to apply finishes. In our shop, Kevin Boyle, WOOD® maga-zine’s master craftsman, says that choosing the right brush is the first step to a successful finish. “Purchase a high-quality natural bristle brush for lacquer, because the bet-ter the brush,the better the result. There’s nothing more irritating than a bristle com-ing out on the final stroke. To brush poly or a water-based finish, use a disposable foam brush.” (Note: Because lac-quer eats foam, never use a disposable foam brush with this solvent.)

So how do you start? “I usually start in the left corner away from me and bring the finish to my right, working from back to front,” Chuck says. (See drawing above.) “That’s so I don’t drop anything onto the fresh finish when reaching across the width.”

After applying the finish, Chuck inspects the piece for areas he might have missed or where not enough was applied. After the finish dries, if he finds any runs, he scrapes and sands them down. “About the only way to correct imperfec-tions is with scraping, light sanding, and buffing,” he says, then adds some final words of advice: “Don’t get in a hurry. Finishing takes time. You put a lot into making the project, so spend the time necessary to finish it correctly, even if it takes as long as the building.”

Glue size on end grain seals the wood and hardens the fibers, making them easier to sand and stain evenly. If you need to seal just the ends, mask the faces and edges before applying the size. Generously brush on glue size (one part glue to 10 parts water), wipe off any excess, and allow it to dry overnight. Then apply the stain.

Stained oak end grain without glue size

Stained end grain with glue size

CHALLENGE: No matter what wood you stain, the end grain always ends up darker than the face grain–even when you wiped off the stain quickly.

More great finishing tips • Use cotton swabs to spread finish into corners and crevices and to unclog dowel holes. • Remove the cabinet back before applying finish. Take off handles and anything else you can remove.• Stuff cotton balls into any dowel holes yet to be filled.• Keep stains stirred throughout application. • Don’t let stain dry before wiping off the excess. Always keep a wet edge. On a large surface, first stain two-thirds and wipe it down. Then, complete the final one-third.

CHALLENGE: You try to be careful, but when you apply finish, your projects end up with brush marks that everyone can see.

Solution 9

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Press and level putty into the damaged area enclosed by two layers of masking tape, which also keeps excess putty off surrounding wood.

For a quick fix, rub colored putty sticks (available from paint retailers and hardware stores) into minor dings. Some types can be blended to create custom colors.

Filling gouges—especially deep ones—leads to a common problem: dips and bumps in your patch. Just when you think everything’s even, the drying process leaves a dip in the center of the patch, which has to be filled. Solve this problem when patching unfinished wood by surrounding the patch area with two layers of painter’s tape, as shown at right. That creates a slight buildup on the surface while preventing putty from filling the pores of the surrounding wood.

After the putty dries, remove the tape to leave a small raised area ready to be sanded with a flat sanding block. Patches may be softer than surrounding wood, so avoid soft or pliable sanding pads that might leave a noticeable depression. Patching finished pieces is trickier, because you need to avoid damaging the surrounding finish. Instead of masking tape, use one layer of transparent shipping tape with the damaged area cut out. Fill and partially sand the patch with the tape still attached. Then, remove the tape, and finish sanding using 400-grit paper on a sanding block that’s as wide as your patch.

CHALLENGE: Every time you patch a boo-boo, the center of the damaged area has a dip in it.

Dents seem to always show up just when you’re ready to apply finish. Here’s what to do: First, moisten the dented area by placing a damp cloth over the depression, and then run a hot household iron over the cloth, as shown at right. The steam will swell the compressed wood fibers, letting you sand them flush when dry.

If dentlike tool marks plague your project, try sanding if steaming fails to eliminate the problem areas. If things have really gone south, mill a replacement part. Or better yet, machine extra stock for spares in the beginning. Another option includes using tool-marked stock in areas where it won’t be seen.

A household iron, a dampened towel, and sandpaper team up to make dents disappear.

CHALLENGE: You’ve just assembled your project, and a catastrophe occurs. You accidentally dent the project while carrying it to your finishing area.

Area to be sanded

Solution 11

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A formed-steel cornering tool, like the one shown above, makes quick work of rounding a corner. This inexpensive tool shaves a round-over as it rides along the corner, guided by a machined groove (visible up close at the raised end of the tool). The tool cuts equally well on the push or pull stroke.

To avoid lifting the wood, always work with the grain. We found that this tool worked well on end grain, too. Each tool cuts two different round-over radii—1⁄16" and 1⁄8" (the one shown) and 3⁄16" and 1⁄4". One source is Lee Valley (leevalley.com or 800-267-8735).

Pull or push the cornering tool along the stock for a quick and easy round-over. Move the cutting edge with the grain direction.

You can chamfer or round-over a sharp corner with just a few strokes of a sanding block. Removing sharp edges gives your project a finished look and feel.

For back-to-basics easing, just wrap a piece of sandpaper around a scrapwood block. Sand across the corner of the work-piece at a 45° angle, as shown at right, to form a chamfer. To minimize the chance of lifting a splinter, sand diagonally across the corner rather than straight along or across it. For a sizable splinter, work glue underneath and hold it in place with mask-ing tape. After the glue dries, sand the edge smooth.

A corner will feel smooth, yet still look sharp and crisp after just a few strokes with 220-grit sandpaper.

You can break a sharp corner with a few passes of a plane too. A block plane forms chamfers conveniently, as shown below. Be sure to plane in the grain direction to prevent lifting the grain. You can plane as wide a chamfer as you prefer.

For a round-over, like the one shown on the stock in the middle of the photo-graph, plane a series of narrow chamfers. You can bring the round-over to final form when you finish-sand. It’s easier to plane a large-radius round-over than a small one.

You can use virtually any size or style hand plane to ease a corner. A spokeshave also works nicely.

A block plane works great for corner chamfering, passably well for rounding over. For fine work, set the plane iron for a shallow cut, and narrow the plane’s mouth, if it’s adjustable. You also could use a spokeshave.

CHALLENGE: Ouch! The crisp edge on a table you built now has splintered and grabs clothing (and skin).

Spokeshave

Block plane

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Solution 14 Solution 15

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CHALLENGE: Lacquer is your favorite finish, but whenever you spray or brush it on, the family complains about the fumes.

You can gauge the danger of any solvent by the toxicity warning on its label. So make sure you always read it for health-risk warnings; then, proceed with caution. Such material requires careful handling and personal protection. (Labels offer little advice for protecting yourself.) But it won’t hurt to exercise reasonable care even with materials labeled as nontoxic or that you know little or nothing about. Nontoxic doesn’t always mean harmless.

Your countermeasures to the possible effects of toxic materials should include ventilation, a respirator, rubber gloves, and hygiene. Each fix below adds a layer of protection and doesn’t cost much.

A half-mask, dual-filter respirator fits comfortably and offers vapor protection.

Ventilation An open door and window, or two open windows and a floor fan, may not provide adequate ventilation. If your shop adjoins liv-ing quarters, a good rule of thumb states that if you or someone else can smell solvent, your ventilation falls short. The drawing above shows a simple situation that provides adequate dilution ventilation (fresh air dilutes the noxious vapor) for brushing or wiping solvents in a basement shop. The ventilator is not intended for spraying flammable finishes. In addition to a flow of fresh air, you’ll need a respirator. Two alternatives: Switch to nontoxic water-based finish, or schedule your finishing to take place during warm months, when you can open up your work area.

Respirators Select a dual-filter chemical respira-tor that fits comfortably over your nose and mouth. Look for one with “NIOSH/MSHA Approved for organic vapors” on the package. These come in both full-face and half-mask models; the latter costs around $25.

Gloves & hygiene Absorbing toxins through the skin is just as dangerous as inhaling them. Disposable latex gloves prove useless when handling many solvents—some chemi-cals pass right through them. Look for gloves made from nitrile in your hardware or paint store. (They cost about $2 per pair.) Always wash your face and hands —even if you wore gloves—after handling solvents.

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Whether in the air or on your work, dust can destroy a smooth finish. Maybe you can’t eliminate the prob-lem, but you can minimize it. To detect stray dust, brush your hand across the wood. To remedy, vacuum your wood after each sanding grit to remove loose abrasives and fine dust. To prevent marring the surface, use a dusting brush vacuum attachment, right, rather than a hard nozzle. Even after the final sanding and vacuum-ing, dust still has time to accumulate before you apply a film finish. Use your hand to detect dust. This also reveals rough spots or dust not obvious to your eyes. Do this between coats as well, and after scuff-sanding and vacuuming. For final cleanup, a fresh cloth dampened with mineral spirits works well.

CHALLENGE: You tried to work in a clean environment, but dust crept into the finish of your woodworking projects.

CHALLENGE: Everyone recommended sanding between coats of poly-urethane. But you sanded right through the first coat and into the stain.

Today’s super-durable polyurethane finishes don’t stick to themselves the way layers of shellac or lacquer bond with previous coats by partially dissolving them. That makes sanding between latter coats essential. By doing so, you remove dust nibs that become trapped in slow-drying, oil-based finishes. You also leave fine scratches that give the next coat of finish a grip on the one below. Scuff-sanding is easy: Just make about four light, uniform passes over the finish using 280-grit abrasive. (A flexible foam pad is ideal.) Check the paper frequently to avoid clumps—called “corns”—that can mar your finish. A flat, rigid sanding block increases your risk of sanding through the finish at the edges and on uneven spots.

Sand-through of stain

Smoothing off dust nibs after your second coat of finish takes only light pressure on 280-grit abrasive—not enough to cause the sort of sand-through shown above.

Flexible foam sanding pad

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Solution 19

Solution 20

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Abrasive cords and tapes help you smooth tiny details in spindles and scroll-sawn work. A .052"-diameter cord removes finish from the chair leg below. The E.C. Mitchell Company makes flexible cord as small as .012" in diameter and tapes as wide as 1⁄4". One source is Klingspor’s Woodworking Shop (800-228-0000 or woodworkingshop.com).

CHALLENGE: When you sand or refinish spindles, you can’t get the gunk out of the beautiful details.

CHALLENGE: The inside corners of your projects are never smooth. If you could just get closer with your block sander.

Use cloth-backed sandpaper, available in strips, to work the inside edges of narrow open-ings. It won’t rip in use, as paper will, but you can tear it to fit the job. 3M markets the strip shown at left. For presized widths in a variety of grits, see Klingspor’s Wood-working Shop (800-228-0000 or woodworkingshop.com).

Reach those hard-to-sand spots with a simple sanding stick. Bandsaw its thick-ness to a wedge shape for flexibility, and then form a point so it fits into the tiniest nook. Apply self-adhesive sandpaper to the end—a different grit on each side. Then, trim the sandpaper to shape with a utility knife.

CHALLENGE: Inside cuts on your scrollsawn projects look rough because you can’t sand them smooth.

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Solution 22

Solution 23


CHALLENGE: You can’t figure out where the lumps come from in your finish. And you thought you did a great job of stirring the can!

CHALLENGE: When you sand with super-fine grits, the wood doesn’t accept the stain.

If you’re sanding up to 320, 400, or higher grits before adding a film finish, you are wasting effort, because a super-smooth surface can’t trap stain pigment. Instead, sand to 150 grit for clear finishes and 180 grit for those receiving a pigment stain first. With the time you save, rub out your final layer of film finish using 0000 steel wool or a synthetic substitute. This knocks off any remaining dust nibs and leaves smoother surfaces. With oil finishes, sand to 180 grit before applying the oil, then sand with 400-grit abrasives between coats for a smooth surface.

Next time, transfer finish from the original can to another container. This helps in two ways. First, you’re not contaminating your original supply with debris from your brush. Second, when working from a partially full can, strain the finish as you transfer it to filter out debris and congealed clumps created as the finish reacts to oxygen in the can. Cheesecloth or a fine-mesh paint strainer available from paint stores and home centers will catch most contaminants. When you complete your project, discard the unused portion, along with any dust and bristles it picked up during use.

Abrasions made by coarser sandpaper trap more stain pigment than finer scratches, saving you time while creating a darker finish.

Sanded to150 grit

Sanded to 320 grit

Unless your shop stays a constant 72 degrees, temperature and water vapor will affect your finish. Problems range from spray lacquer turning cloudy because of moisture vapor entering the finish to water-based finishes drying too quickly in arid climates, trapping bubbles and brush marks. If possible, postpone fin-ishing until a day when nature cooperates. Otherwise, coping strategies for less-than-perfect conditions include warming your shop in the winter while a finish dries. (Just avoid expos-ing combustible fumes to open flames or heat sources.) In dry conditions, steam vaporizers and humidifiers adjust indoor humidity to optimum levels. To apply lacquer in mildly humid conditions, add a retarder to spray finishes, or use brushing lacquers that dry slowly enough to prevent the finish from clouding. The chart at right will help avoid problems.

Application Ranges for Common FinishesFinish Temperatureº F Humidity

Lacquer 50–90º 25–55%

Oil/Varnish 40–100º 25–55%

Polyurethane 50–90º 25–55%

Shellac* 40–80º <85%

Water-based 60–100º 25–50%

* Do not apply when temperature is within 10º of the dew point.

CHALLENGE: Last spring, you spent a wet, rainy weekend finishing a tabletop, and wound up with a cloudy result.

Solution 24

Solution 25

Solution 26

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CHALLENGE: You ruin more good brushes—even when you clean them promptly. Buying new ones gets expensive.

Don’t give up: You simply need to use the right solvent to dissolve the finish on the brush. As the chart below indi-cates, there are solvents for every kind of finish. Although all of these liquids commonly are called solvents, note that they’re also used as thinners. A solvent dissolves certain solids. (A thinner mixes with a liquid and dilutes it.)

Take precautions when using these substances, because overexposure in liquid or vapor form can cause a range of short-term and long-term health problems. For example, toluene is considered a probable cause of cancer. Wear protective gloves when cleaning brushes.

To clean, brush out as much finish as possible onto paper or a piece of scrap. Soak the bristles in the appropri-ate solvent, and work it in with your fingers.

When the bristles feel clean, shake the brush to remove most of the solvent. No matter which solvent you started with, finish cleaning the brush with soap (dish soap works well) and water. Rinse out the soap, and spin the brush to remove the water. Place the brush in its original cardboard jacket, or wrap it with paper from a grocery bag to keep the bristles straight and clean.

Mineral spirits (paint thinner)Naphtha

Wax Wax, oil, varnish, polyurethane

“Paint thinner” is essentially the same as mineral spirits. Use a product with either label to clean varnish or oil-based paint from brushes.

TolueneXylene (xylol)

Wax, water-based finish, white glue, yellow glue

Wax, oil, varnish, polyurethane, conversion varnish

These very toxic chemicals can be used to soften and remove dried yellow glue.

Denatured alcohol is poisonous. It’s made that way so that it can be sold without a liquor tax.

Shellac, lacquerShellacDenatured alcohol

Lacquer thinner Lacquer, shellac, water-based finish

Lacquer, catalyzed lacquer, shellac

“Lacquer retarder” is a special form of lacquer thinner that evaporates more slowly; add it to lacquer when working in hot or humid conditions.

Removes adhesives, including contact cement, and resins. However, it can damage plastics.

LacquerLacquerAcetone

Here’s how to use solvents

Solvent What it dissolves What it thins Comments

Solution 27


CHALLENGE: You did an excellent job of sanding an oak dining room table. The finish went on well, but the top didn’t turn out glassy-smooth. It’s loaded with tiny pits.

Craftsmen select oak again and again for their best furniture projects. Oak is readily available, durable, easy to work, and attractive. However, an oak tabletop or desktop finished with only stain and a topcoat lacks the super-smooth feel that people check for with their fingertips. Its pores may appear tiny, but they’re big enough to catch the tip of a pen or pencil as you write on paper, and can trap bits of dirt or food. Also, that slight roughness breaks up the pleasing sheen that’s easy to achieve with a truly smooth surface.

You could make the surface level with several coats of clear finish, but we recom-mend filling the pores first. It’s quicker, saves on finish costs, and produces glass-smooth results with your first topcoat. You can see the difference between unfilled and filled oak in Photo A. Use this tech-nique only on large, flat, horizontal surfaces to get the biggest benefit and to keep the task manageable. These same steps also apply to other open-grained woods such as ash, mahogany, and walnut.

What’s the problem?Cut through a log and you see that wood contains countless hollow tubes—the ves-sels that carry sap. When a sawmill cuts the log into boards, some of those tubes get sliced open, leaving exposed pores in the shape of holes, and small channels on the surface.

Sanding doesn’t eliminate these pores. A film-forming topcoat can bridge them, but it’s a weak layer that’s likely to give way over time. Paste filler, however, cre-ates a smooth, solid base for your finish, as shown in the drawing at right.

To help you fill in the grain of an upcoming project, let’s look at one popular solution.

Paste filler to the rescuePaste filler, a mixture of solvent with silica or a similar material, is a bit pricey (we paid $17.95 for one quart) and somewhat messy. However, many experienced wood-workers choose this approach, because it gives excellent results and requires less

We applied stain and one coat of lacquer to the oak sample, left, leaving the pores unfilled. The silky-smooth sample at right received stain, paste filler that was tinted with the same stain, and a coat of lacquer.

sanding than other strategies. Paste filler comes in water-based and oil-based for-mulas; we recommend oil-based for ease of use and versatility. Look for paste fillers at a woodworking store, or mail-order them from a woodworking catalog.

Some paste fillers are ready to use right out of the can, while others require thinning. You want the filler to pour like heavy cream; if it’s thicker than that in the can, scoop the amount you need into a smaller container, and add mineral spirits as necessary.

The color of the filler affects the final appearance of the wood. It’s usually best to use a filler with the appropriate tint. You can buy paste fillers that are tinted already, but usually, you get more use from a can if you buy neutral, pour the amount needed for your project into a separate container, and add tint to produce the exact color you want.

To tint neutral oil-based paste filler, pro-ceed as shown in Photo B on the next page. If you want the pores to match the rest of the wood, you can use an oil-based stain that you plan to use for your overall project color Or, you can use any colorant

that’s compatible with your filler. With an oil-based filler, your options include artist’s oils, Japan colors, oil-soluble dyes, and universal tinting colors.

Look for these colorants at woodworking stores, woodworking catalogs, or in artist’s supply stores. For example, Woodworker’s Supply (800-645-9292 or woodworker.com) offers a good selection of colorants.

Begin by sanding your wood through 180 grit. If you want to stain the wood, begin the finishing process by applying a coat of your chosen stain. When the stain has dried completely, seal it with a light coat of either dewaxed shellac or your final finish. (If you don’t plan to apply stain, start with a light coat of shellac or finish, and proceed as follows.) Allow the shellac to dry, and then sand lightly with 320-grit sandpaper. With this step, you color the nonporous areas to your liking and protect that color from being altered in the follow-ing steps, when you add the desired tint in the pores.

Now, you’re ready to fill the pores, as shown in Photo C. See Photos D and E for two of your many options.

Allow two or three days for the filler to dry. When dry, sand lightly with 320-grit paper to remove any traces of filler without sanding through the sealer coat.

One application of paste filler might not produce perfect smoothness, and you might choose to repeat the process. In most cases, however, one application should make the imperfections shallow enough so that your topcoats of clear finish can easily complete the leveling process.

A

Solution 28

woodmagazine.com 15

Pore-O-Pac, a paste filler made by Behlen and available from Garrett Wade (garretwade.com), requires little or no thinning. Simply add colorant, and it’s ready to use. Here you see one sample color using a burnt sienna artist’s oil. We’re mixing a burnt umber Japan color (which is easier to mix into filler).

Here’s the stain/shellac/paste filler sequence again, but this time we increased the contrast by tinting the paste filler with Van Dyke brown Japan color.

Pour the filler onto the wood, and then spread it with a plastic spreader or a rubber squeegee. Force the filler down into the pores as you go. When the pores are filled level with the surface, scrape or drag off the excess filler at a 45° angle to the grain. Still, a light coating will remain. As the solvent evaporates, or “flashes off,” the surface loses its wet look within a few minutes. When it appears dull, rub across the grain with burlap or coarse cloth. If the filler begins to set up too quickly, making removal difficult, sprinkle mineral spirits over the surface, and then rub off the excess filler.

This red oak above received a coat of Salem maple stain, followed by a light coat of shellac. Then, we tinted paste filler with the same stain, and filled the pores.

Two paste filler options

B

C

D E


CHALLENGE: You have a number of boards in the same species that vary in color. You need a way to lighten the darker boards. You experimented with household bleach on scrap, but couldn’t get rid of the wood’s natural color.

wet to minimize streaking. (We held the board at an angle and worked from the bottom up, as shown below left.)

Rinse the solution off the wood with water. To ensure that no caustic soda remains, rinse the wood with a mild acid—household white vinegar works well—then rinse it once more with water.

After the wood dries, assess the color. You can bleach wood as many times as needed to achieve the color you want. (We bleached the pale piece of red oak in the photo above twice, and made three applications to the walnut sample.)

Allow the wood to dry thoroughly. Then, sand with 320- or 400-grit sandpaper—just enough to remove the fuzzy grain.

So be sure to read the manufacturer’s instructions and warnings before use. And always wear rubber gloves and eye protec-tion while working with bleaches.

Now, kiss that color good-byeThe Wood-Kote brand bleach we tried comes, like most, in two bottles. To use it, mix equal parts of the two liquids in a glass or plastic container, as shown below left. Never put either chemical into a metal ves-sel. (Some bleaches call for applying the two parts separately. Follow the instruc-tions for the bleach you’re using.)

When mixed, a chemical reaction begins, where the hydrogen peroxide, an oxidizer, acts to neutralize the caustic sodium hydroxide. Neutralized, the solu-tion loses its bleaching power, so mix only what you can use immediately.

Quickly apply the solution to the wood. A sponge makes a good applicator, as shown below. Keep the surface uniformly

Apply the bleach as evenly as possible, and keep the surface wet as you work.

Work fast after mixing the two chemicals. The solution begins to neutralize—and lose bleaching power—just as soon as you start to pour the liquids together.

After bleaching, the oak and walnut are the same color. The grain remains visible in both pieces.

When it comes to altering the color of wood, woodworkers routinely turn to stains to give wood more—or a slightly different—color. But wood bleach lets you remove color from wood. The process begins with choosing the right product.

Look for a two-part bleach to do the jobYou’ll find three kinds of products mar-keted as wood bleaches. But only one removes the natural color from wood: a two-part wood bleach of sodium hydrox-ide (caustic soda) and hydrogen peroxide. Other wood bleaches are chlorine bleach and oxalic acid.

Chlorine bleach, which is like ordinary laundry bleach, removes dye color from wood, but not the wood’s natural color. Oxalic acid is commonly employed to bleach out water or rust stains.

All the bleaching chemicals pose vary-ing degrees of health and safety hazards.

Why remove the color from wood?Wood bleaching proves useful in situations like these:• When the wood you have is too dark for a particular project. In this case, removing some of the color from the wood might make it more suitable, or would allow you to stain the wood to a lighter color. • When you have several boards of the same wood for one project, and they vary in color. Here, you can bleach one or more of the boards to match the others. Or bleach all the boards and stain them to a consistent color.• When you want to stain one wood to look like another. Removing the natural color from a wood makes matching the color of another wood easier. If you bleach both woods, you can stain them the same color.

Solution 29

woodmagazine.com 17

Before applying oil-based polyurethane, make a sanding sealer by mixing equal parts of poly and mineral spirits (paint thinner). The same ratio, with appropriate thinner, works for oil-based varnish or lacquer.

CHALLENGE: Even when you sand projects thoroughly, the first coat of finish dries as rough as a cob.

Under lacquer and oil-based varnish: Simply choose a sanding sealer that contains the same material as your topcoat, brush or roll on a liberal coat, and allow it to dry. Sand with the grain using 320-grit sandpaper to produce a powder like that shown below. Wipe away the powder with a cloth—damp-ened with mineral spirits (paint thinner) if the topcoat is varnish—or vacuum it off. As an alternative, use a thinned coat of lacquer or oil-based varnish as the first coat. Mix lacquer 50/50 with lacquer thinner, or mix varnish 50/50 with mineral spirits.

Under oil-based polyurethane: This popu-lar finish doesn’t bond well with sanding seal-ers, so it’s a prime candidate for the “thinned first coat” approach. Thin it as shown below, brush or roll it on, and you’ll sand the first coat smoothly with little effort.

Under water-based polyurethane: Water-based sanding sealer works fine, but provides a relatively small benefit, because the finish itself sands easily when applied full-strength. Don’t thin water-base; you’re likely to have problems due to its complex chemistry.

We brushed lacquer-based sanding sealer onto this walnut sample board and let it dry. Light sanding produced a powdery residue that didn’t clog the 320-grit sandpaper.

3 sanding sealers at a glanceType

Lacquer sealer,mineral spirits-based or water-based sealer

50/50 mix of topcoat and thinner

Shellac

Use it when...

you’re working on a large surface

you’re finishing a small project

you need a barrier coat between the topcoat and substances (such as pine knots oozing resin) that inhibit good adhesion

Be careful because...

polyurethane (unless thinned) doesn’t bond well with sanding sealer

it’s easy to sand through this thin coat to the stain coat orbare wood

a heavy first coat of lacquer can dissolve through shellac

You also should know...

two coats is the limit; a thicker layer leads to a soft, easily damaged finish

this is a good method with oil-based polyurethane, but not with water-based polyurethane

shellac containing wax can cause adhesion problems; always buy a container that’s labeled “wax-free”

Solution 30

Solution 32

Solution 31


Congratulations, your project has reached the finishing stage. But now’s no time to abandon the care and patience that’s brought you this far. When the label on the can tells you to let the stain dry before finishing, believe it. Take even greater care with tung and linseed oils (found in many stains) used beneath film finishes. When you rush into covering these with a film finish, the oil creates a “bloom” that clouds the finish. Give oils about a week to completely dry, depending on weather conditions. Then, allow each coat of finish to dry thoroughly before applying the next.

CHALLENGE: A few minutes after the pads on your random-orbit sander slip, you have fine dust all over the shop.

Here’s a simple way to hold the panel off your workbench so you can apply stain to both surfaces in one setting. Use triangular cutoffs from your scrap bin, which support the workpiece only on their “peaks.” Drilling holes in the cutoffs and inserting a dowel helps keep the blocks from tipping over. Slide the blocks along the dowel to suit the workpiece width.

To make your pressure-sensitive-adhesive (PSA) pads stick better, pre-heat the sander’s pad with friction by running it against a nonmarring surface such as a scrap of carpet. You’ll discover that PSA pads won’t stick to a cold pad but will adhere readily to a warm one.

CHALLENGE: You tried to cut corners with your finish coats by shortening the drying time. What you ended up with was a cloudy finish.

CHALLENGE: You stained the back of a panel and then turned it over to stain the front. Unfortunately, the wet panel stuck to your workbench.

Solution 33

Solution 34

Solution 35

woodmagazine.com 19

CHALLENGE: You made a laminated cutting board but after a very short time it split at the joint lines.

CHALLENGE: You spent a lot of time and followed all the instructions but your table still doesn't have the high-glossfinish you were trying to achieve.

Solution 37 1For tight-grained woods, such as the

maple shown in this project, sand the surface to 220 grit, and you’re ready to apply the finish. An open-grained wood, such as oak, ash, walnut, or mahogany, requires the use of a matching-color paste grain filler. Pack the grain by working the filler cross grain with a wide putty knife. Let the filler dry, and then sand the surface to 220 grit.

2To make polyurethane finish flow out smoothly without brush marks, add

three tablespoons of paint thinner to one quart of high-gloss finish. Do not use fast-drying polyurethane. Brush on three coats, sanding with 220-grit sandpaper between each coat.

3Sand the third coat of finish with 320-, 400-, and then 600-grit sandpaper.

Remove the sanding dust. Inspect the surface for flaws by wiping it with thinner, and shining a light across the surface at a low angle. Spray on a fourth coat of gloss polyurethane from an aerosol can, uni-

formly wetting the whole surface. Let the finish cure for a week.

4Remove any dust motes with 1,500-grit sandpaper. Make a pad with a

soft cotton rag, and buff the surface to a high sheen with 3M Finesse-it II Finishing Material (available at auto-paint supply stores, or buy it online at properautocare.com).

Properly sealed, cutting boards will last for decades. But, if the finish wears down and moisture gets into the wood, delamination and warpage could occur. To pro-tect cutting boards, wash them with a warm soapy cloth instead of immersing the board in water or plac-ing it in a dishwasher. When the finish appears to be wearing thin, brush on a food-grade oil or salad bowl finish. If the board’s appearance suffers from knife cuts, resand before applying new sealing coats of finish.

Solution 36


CHALLENGE: You just finished your project and then dropped a tool on it lightly denting the surface. Now what do you do.

CHALLENGE: You want to apply a finish to your oak project that blackens it but you can not remember what you mix with the vinegar.

Solution 38

Solution 39

Fill the dented area with water from an eye dropper. Repeat until the dent rises up flush with the surrounding surface.

Add a little iron. Iron mixed with white vinegar produces a centuries-old finish, called “iron buff,” that can be brushed onto oak, and most other woods, to darken their color.

To make iron buff, rinse a pad of steel wool with lacquer thinner to remove the protective oil. Allow the pad to dry. Then tear the pad into pieces and soak them in a pint of vinegar until the acid begins to dissolve the steel. Soak the pad overnight for a light color change or for a week to achieve darker colors. When a dab of iron buff turns a test board the desired color, strain the solution through a tightly-woven cloth, such as an old t-shirt, to remove the largest pieces of undissolved iron. Then strain it again through a coffee filter to remove the remaining particles.

The vinegar itself doesn’t change to a dark color that dyes the wood. Instead, the iron in the vinegar reacts with chemicals in the wood, causing them to change color. Because it’s a chemical process instead of a wiped-on stain or dye, you get blotch-free

color. Each batch will vary, though, so mix enough to stain an entire project. Apply an optional oil-based stain to deepen the gray or black color for a darker tone. Then apply a film finish.

If you’ve got a shallow dent and the wood fibers are not torn or broken, a few drops of water will swell the fibers and cause them to return to their original position. As shown in the photo at left, apply the drops of water with an eye dropper, and wet only the dented area. Check the workpiece every hour or so. If the water soaks in, add more water until the dent is gone.

After soaking the wood, you’ll probably see a small water stain and some fuzzy wood fibers where the dent was. Let the wetted area dry thoroughly, and then sand the spot until the water stain and raised fibers disappear.

You sometimes can get quicker results by steaming the dent with a clothes iron. Be careful not to scorch the surface of the wood or raise the grain on a large section. Instead, wet the corner of a rag or towel, place it in the dent, and steam the dent through the rag with the pointed front end of the iron.

woodmagazine.com 21

CHALLENGE: You forgot to put out coasters and hot pads at last night’s party. In the morning, you found a white ring on a table. And a neighbor scorched your tabletop with a hot casserole.

Water and heat rings rank high on the list of common finish damage. Here are some tips that just might make them go away.

“There are no guarantees when it comes to removing water and heat rings,” accord-ing to furniture repair and finishing ace Jim Kull of McKinney, Texas. “Some methods for getting rid of white marks are poten-tially damaging to the finish. And ulti-mately, all efforts may fail, leaving strip-ping and refinishing—or living with the marks—as your only options.”

But if you’re game, it might pay to try some of these tricks before you resort to refinishing.

Let’s see what you have Start by assessing the wood damage. “A simple repair may be possible for finish discoloration—damage that doesn’t pen-etrate the wood,” Jim says.

The mark itself will tell you a lot • A white mark signifies damage to the finish only. • A darker mark denotes damage that’s gone through to the wood.

Check the surface, too• An unmarred surface over the mark gen-erally indicates moisture damage.• A slight indentation over the area usu-ally points to heat damage.

What kind of finish?Here’s how to determine whether the fin-ish you’re dealing with is lacquer, shellac, or something else.

• Dab a little denatured alcohol onto the finish in a hidden spot. If the finish softens, it’s shellac. • If it doesn’t soften, try the same thing with lacquer thinner. If the finish softens now, it is lacquer.• If neither has an effect, you’re contend-ing with some other finish.

Begin the repairFor lacquer or shellac, clean the area thor-oughly with paint thinner. Then, wash it with a mild soap such as Murphy’s Oil Soap. Wipe it down again with paint thin-ner, and let it dry.

Wet the finish directly over the mark with alcohol (for a shellac finish) or lacquer thinner (for a lacquer finish). “It’s best to spray it on,” Jim says, “but you could brush on a wet coat and leave it. Don’t rub it.” The solvent dissolves the finish, which will reflow as it dries, maybe erasing the mark. “This may not work,” Jim cautions, “but it’s worth the effort.”

Try buffing for other finishes“Buffing is my least favorite approach; it rarely works for me,” Jim warns. “And you can easily polish right through a thin finish.” If you buff, apply a fine-grit automotive polishing compound with a high-speed buffer and a lamb’s-wool pad.

Now, let’s dive into water marksJim reports mixed results with commercial white-ring removers. The Jasco ring-remover cloth, shown below (from Ace Hardware, acehardware.com), renders most rings less visible. An almond stick works in many cases too. With either, the rings may reappear after time.

Go for the grease An easy fix to try is to smear mayonnaise, petroleum jelly, or shortening on the mark. (Jim likes mayo on his furniture because it’s easier to clean up.) Slather it on gener-ously, and leave it overnight. The idea is to let oil seep in to clear the mark.

“If that didn’t quite do the trick, try again,” Jim counsels. “If another applica-tion doesn’t get it all, you need to try something else.”

Beyond sandwich spreadThat something else would be wiping gen-tly with denatured alcohol. “But be care-ful,” Jim cautions. “Alcohol will dissolve shellac, mess up a lacquer finish, and dam-age some water-based finishes.”

For this procedure, fold cheesecloth or cotton fabric into a pad, and dampen it with alcohol. It should be thoroughly damp, but not wet.

“Then,” Jim explains, “gently, gently, gently wipe the pad over the ring area. Swing your arm, brushing the pad across the mark much like an airplane landing and taking off, with the landing being very soft. Don’t rub,” he says. “A slight haze should appear; this is the alcohol evapo-rating and, we hope, taking the subsurface moisture with it.”

If that doesn’t happen, you could try the same tactic again, but using lacquer thin-ner. “This technique, which is best left to pros, could totally destroy the finish,” Jim warns. But by this point, you may have become resigned to refinishing, anyhow.

Play it cool with heat marks“Often, your only solution for heat marks is to strip and refinish the surface,” Jim says.

Take your pick of tricks for clearing up white rings on furniture.

Rubbing with this chemically treated cloth minimizes the white mark.

Solution 40


from the editors of WOOD®

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