MASONRYand

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STONEWORK

By Jack WorkMainline Modeler Staff

FIG. 1

Masonry and stonework introduced into a model railroad, be it inthe form of retaining walls, structure foundations, tunnel portals, orwhatever, can bring a great deal of character and nostalgia to the

scene. It must appear realistic to be convincing. Simulated stoneprinted on paper is not convincing.Embossed plastic comes closer butit’s difficult to make it look like real stone. Another method I’ve seenis to coat an area with plaster and then shape stories into it while wet.This also falls short since the surface sets smooth and making impress-ed into it result in smooth rounded edges. If carved after setting, theknife blade or any such tool, will again leave a smooth surface. Noneof these approaches create the feeling of strength and ruggedness weexpect of stone construction. I’m convinced there’s no better way thanto fracture plaster to expose the grainy textured surface we’ve come toknow as broken stone. The following discussion explores various ap-proaches toward this end.In the aforementioned work, as in many areas of model building,

pleasureable as it may be, some repetative steps can become tiresome.Aside from this boredom, fashioning part after part of the same itemto appear identical each time is often difficult if not impossible. So it

was, early in my exposure to the hobby, I turned to the use of rubbermolds and thus began a crude rfactory process’ for reproducing iden-tical parts in quantity. In our following coverage of masonry andstonework we’ll see how this casting technique is applied to this

specific work.While experimenting with this mold-castingprocedure I discovered

something else. It became apparent some hobby items could best bearrived at by starting with small components that would stack or (key’together to build up larger components. This speeds the work at thesame time offering flexibility and variation. Such is the case in someof the examples shown here. The real payoffhowever, is that once the

pattern and mold have been made for a given piece, that part of thework is done forever. Thereafter it is simply a matter of filling themold to reproduce parts as required. Often one can draw on this stockof parts to be used in many different applications around a modelrailroad. These stone castings are an excellent example of this.I’ve found this work to be fascinating and challenging. Certainly it

has allowed me to turn out a much better product than might havebeen otherwisepossible.At any rate, those who do not wish to involvethemselves with the mold and casting process can still employmethods shown to build up stonework of whatever size for a solitaryproject. Before getting into this business there are a few generalpoints we should consider.

Here we see just one example of masonry we can try to duplicate.There stone footings, located in a river bed, support a steel railroadbridge. Note, the upstream ends at least, are pointed to preventdebris, washing down river, from handing up on the footings. Thereare different methods of assembling stone and one should watch forvarious arrangements employed in prototype applications. The rows,or courses ofstone shown here, are not all of the same weight, but allstones in a given course are, so each course is uniform throughout.Another effectmixes stones or irregular size so no uniform courses areevident. Notice the face of each piece has a definite appearance ofhaving surplus stone broken away. This can best be simulatedrealistically in modelform as shown in Figs. 3 and 4.

PATTERNS:Remember, each reproduction from the mold will be identical to the

pattern from which it was taken. This means it will include any flaw inthe original as well! Thus I urge the reader to lavish all the time

necessary on the 'master’ so it will be as near perfect as it’s possible tomake it. Only one need be built so the extra time spent on it is willworthwhile. :

SCALE:Little will be said here regarding dimensions or scale size. When we

deal with locomotives. rolling stock, trackwork,and the like, we expectto adhere to rigid specifications, and rightly so. Once we leave this

area and get into scenery, something of an art form, scale is not soeasily defined and dimensions not as critical. Always remember thatsuch things as trees and rocks can hardly be said to have a definitescale as they are considered by themselves.They do however take on adefinite scale when placed beside objects of known size and scale suchas rolling stock, autos, and human figures. Stonework shown here wascreated for H0 scale but could pass in a slightly larger or smallerscale. It would simply cause each individual stone piece to appear alittle larger or smaller than in H0. One should try to observe proto-type stonework if possible to get an idea of stone sizes employed.

COLOR:Coloring too is difficult information to convey. It cannot be

measured with a scale rule the way we impart information in otherareas of the hobby. Here again one should be observant in your daily

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FIG. 2

travels to record in mind the general coloring of prototype retainingwalls, structure foundations, and the like. There you will note manyvariations from blue-greens through grays to browns or tans. Thesewill likely be intermixes - but all very subtle of course. One importantfactor, as with all coloring in the outdoors, it is being viewed under theinfluence of bright daylight, or even brighter sunshine. Rememberthat our indoor lighting is much weaker than daylight, thus a givencolor will likely appear much darker when brought from outdoor in in-door lighting and so allowances should be made.

MOLDS:Molds are formed of Dow Corning Silastic. General Electric has a

similar product as well (check the Yellow Pages for one of thesedistributors, likely listed under Silicones). RTV stands for roomtemperature vulcanizing,which simply means it cures without heat. 1

have used Dow Corning #502 RTV which I believe has now beenreplaced by #3110 RTV, available in quantities of one pound orlarger. A catalyst, available in several types for varying uses and cur-ing times, is sold separately and the type must be specified whenordering. Because of this it is suggested the reader write thedistributor for literature on the uses and properties #3110 RTV rub-ber and catalysts for moldmaking purposes. Catalyst ”F” (fast rate)for example, has a cure time of 5 - 12 hrs. 1 would prefer the shortercuring time but either will do for our purposes.

Short lengths of stripwood are cemented to a scrap wood base asshown. These are spaced to accommodate the various widths ofwaterputty blocks produced as seen (C) in Fig. 2. These spacingswould thenbe 12", 15” and 21 ”. The wood strips I usedfor H0 scale were 12”thick, indicated as dimension ”D” in Fig. 3.The operation here is, resting an Xacto or similar saw across the

wood strips, to make a light sawcutoround allfoursides ofeach block.This cut eventuallyforms the mortar joint between blocks as they ’refitted together. Remember, this mortarjoint is doubled in the process,a portion on each block, so keep the sawcut very shallow - 2 singlelight stroke is usually sufficient.

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To get started we must prepare a supply of 'stoneblocks’ following the steps shown here. Start withstripwood 18” thick in widths of 12”, 15” and 21 ”.

Cut this material in lengths ranging from 15” toperhaps 36". These dimensions (in your particularscale) are arbitrary and can be adjusted to agree withyour own observations of prototypes you may en-counter. These wood blocks are cemented to a scrappiece of plywood seen at ”A”. These should befastened so the 18” dimension rises above theplywood base, or conversely, so all cavities in themoldwill be 18” deep while widths ofopenings in themold will varyfrom 12” to 2]”.Shown next to these is another group of similar

wood blocks with a wood fence cemented aroundthem. This fence is to contain liquid silastic as it ispoured toform a mold ofthe blocks. A resultingmoldis shown at "B" and another (hand-held) is beingemptied of castings. Castings are made of DurhamsWater Putty but Plaster ofParis can be used instead.Resulting water putty castings are shown at "C”, asupply of which are required before proceeding tothe next step.

CASTING MATERIAL:Durhams Water Putty (available at hardware and building supply

stores) is my favourite casting material for many things in the hobby.It sets quickly, does not shrink, registers detail faithfully, and can becarved or filed when set. I’m told Hydrocal is another good product ofsimilar qualities but not having tried it 1 cannot comment. For the ac-tual casting of stonework however I find it hard to beat Plaster ofParis. Being softer and more porous than water putty it absorbs stain-ing colours more readily and in general lends a more realistic stoneappearance. This softer quality can be a detriment for makingoriginalpatterns of plaster - it wears and smooths with repeated handling andtends to lose sharp detail. Water putty on the other hand is harder andstands up well for this pattern work. I use both materials and suggestthe reader experiment with both to become familiar with their respec-tive qualities.

1 have used water color mixtures to stain this stoneworkbut general-ly prefer a thin stain of turpentine tinted with artists oil colors. Thisstain should be thin enough to soak up readily - we do not want a thickmixture that will sit on the surface to clog up the texture of the stonesurface we have tried so hard to create. Chances are the reader hasalready developed his own methods and skills of staining plasterscenery.With these basic thoughts out of the way, let’s move on to actual

steps involved in forming masonry and stone construction. We willalso get into molds and castings for those who wish to go into this partof the work.

X-ACTO SAW

FIG. 3

TWIST KNIFE BLADE////>; /'BNR2:IVXIV1YT°STON.

x”SAWCUT

FIG. 4Dimension ”D” on the sketch is that por-

tion of the water putty block corresponding tothe thickness (12” in H0) ofstripwood piecesshown in Fig. 3. A knife blade, resting fulllength in the sawcut, is twisted outward towardtheface ofthe block. The idea here is to breakaway the unwanted portion leaving a roughfractured surface to the stone. This operationis repeated on allfour edges to complete eachstone block.

Larger sections may be formed initially but sizes similar to thatshown can be used to speed up the creation oflarger units later (seeFig. 8 through 10). The shape of section #1 is random. Section #2 is

nextformed and its ’ shape is random as well. Nextform section #3 tomate with the original two. Start \byfitting stone blocks to mate withsection #1 at left as shown. This completed, beginfitting stones to theright side to mate with section #2. This will require cutting stones tocorrect length to properlyflll the gaps. This can be seen, with largersections in Fig. 10. Continue sliding these sections together and apartas this work progresses to ensure a closefit at all times. These sectionsare to become patterns and all pieces reproduced from their moldswillfit together no better than these patterns.Next, section #1 is moved to the right ofsection #2 and afourth one

is formed between these two to mate with each other in the same man-ner described for section #3. Thus we ’11 have created four sectionsthat mate in a sequence repeatedly, once they’ve been reproduced inquantity in molds shown at left of the photo.

FIG. 6Here we see a group that interlock with each in sequencefrom #1 through #8. There is no

magic number, carry it asfar as you like. Section #9 in this collection is a 'key’piece used tobreak up the sequence and alter the pattern. The left side of#9 mates with the left side of#3.Creating more than one 'key’ the pattern could be varied evenfurther. Working with toofew

FIG. 5Cement two wood strips to a scrap wood base as seen here. The

distance between determines the height, or number of courses, of thestone section produced, and this is arbitrary. Spacing of the stripsshould accommodate a given number of courses snugly. It is criticalthat the distance between strips be uniformfrom end to end. This per-mits stone section to slide along between guiding strips as one ismated to another duringformation. It follows then that stone blocksare cemented to each other but not to the wood work surface. Use aminimum of white glue (Bondfast or other brand) to join blocks toeach other. Periodically move the stone assembly back and forth tokeep it free of the work surface at all times.

sections means any outstanding visual feature will be repeated toooften. This becomes apparent as an undesireable 'wallpaperpattern’effect which should be avoided. Obviously, aside from fitting end toend in sequence, these castings will build up one row above the otherto expand in that direction.

FIG. 7BREAK STRIPSINTO PIECES

USE ASSTONE FACES

Qé'PLASTER OF PARIS POUREDONTO PLASTIC SHEET

FIG. 7Another way to create a broken stone effect starts with a mixture of

plaster poured onto a sheet plastic surface (a bread wrapper will do) asseen here. This should be about 3/8” to 1/2" in thickness (about 36”or so in H0 scale). When thoroughly set it is cut into strips as shown.The strips are snapped (not cut) into smallerpieces. This breaking ac-tion creates a realistic fractured stone surface that is difficult tosimulate in any other manner.

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FIG. 8The supply ofsmall stones sections (left ofphoto) were created, not

by the sawcut and knife blade breaking process, but by snappingplaster into small pieces as shown in Fig. 7. These small pieces arethen trimmed on the back surface with a knife blade, reducing each toa somewhat uniform thickness, about 18” H0 scale, an arbitrarydimension adjustable to your own wishes. Each stone piece is then slic—

ed onfour sides to create a rectangular shape, each beingfitted to its’location, trimming as needed so there are no gaps between pieces. Anysmall openings that do remain can befilledwith wet plaster. The im-portant thing is this trimming,fitting, andfillingofopenings, is to re»tain at all costs the rough broken texture of each stone face.The small sections shown can be used around a model layout as they

are or they can be used toform larger patterns as is being done here.Construction of all these sections, large or small, follows exactly thesame procedure discussed in Fig. 5.

FIG. 9Again, following the procedure outlined in Fig. 5, two sections are

formed ofrandom shape. These are designated here as #1 and #3. Sec-tion #2 is then formed to mate at its ’ left with #1. Remember, duringall this work offorming and mating ofsections, each piece is stillfreeof the work surface so they may be moved about as necessary. It isonly at the time of making a mold that a given section is fastened per—manently to a wood surface. At left is a silastic mold of one of thesesections.

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FIG. 10Here the work has progressed to the point where section #2 is being

mated on its ’ right side with #3. Bits ofplastermust be customfittedin each course to accomplish a proper meshing. At the top of thephoto are pieces ofplaster to be broken into approximate sizes fortrimming into individuallyfitted stones. One must realize there isgreatfreedom in this work. The size and configuration ofeach sectionis not important. The number ofinterlocking sections in a sequence isnot too important. The one thing that must be adhered to, in orderthat a sequence can repeat, is to have the left side ofthefirst sectionmate with the right side of the last in any group.

IQ.

FIG. 11With patterns completed they can now be cemented to a scrap wood

surface in preparation for making the mold. Fill any slight gaps bet-ween pattern and wood surface with wet plaster to prevent moldmaterialfrom creeping under the pattern. Be careful in this work so asnot to have any excess plaster interfere with the mating edges thathave been prepared up to this point. A stripwoodfence is cementedaround the pattern to contain the liquid silastic as it ’s poured. Strip-wood pieces should rise above the thickness of the pattern by about1/8". A thick mold makes it more difficult to remove the casting. It ’simpossible to give hard andfast rules, only experience gained in moldmakingwill teach what is needed. Casting ofveryfinely detailed partsrequires special care in mold formation, heavier work such as thesestone castings allows a great deal morefreedom.Silastic poured over water putty, plaster, or most any material will

usually pull away cleanly. In the example shown, modeling clay hasbeen used to fill some joints between smaller stone sections. Since itwas found silastic seemed to adhere to this clay, a light dusting ofpowdered graphite was applied with a brush over the pattern to pre-vent this. Be certain to blow away all excess graphite.

FIG. 12To create a mold, afew drops of catalyst (tube in foreground) is mixed, using an artists’

pallet knife, with a quantity ofsilastic to begin the curing action. I’ve found a sheet of heavyglass to be an ideal mixing surface, it can be cleanedfor repeated use, even cured silastic canbe peeled away. Just be sure the glass edges have been ground or sanded smooth to preventphysical injury when handling.Here we see silastic being transferred to the fence-enclosed pattern. Try to mix no more

than is necessary, however ifit appears too little has been prepared don’t panic. Silastic willadhere to itselfso a second batch may be added with no ill effect, even after the initial batchhas cured. It’s important to tap, or in some way vibrate, the base to which the pattern is

fastened. This will cause air bubbles trapped in the silastic (during mixing) to rise awayfromthe pattern surface. If not done, there ’s a chance the mold will be marred and resultingcastings will register bubbles on their surface. With the moldpoured, and there should be aslight excess ofsilastic, press apiece ofglass over the mold until it rests upon the woodfence.This willforce excess silastic over the edges of the fence and create a smoothflat surface tothe mold. Ifthis is not done an irregular mold surface can distort the mold and castingwhenlaid on its’ back for filling.

FIG. 14With the moldfilled and resting on aflat

surface, carefully scrape away any excessplaster as shown. Attempt to create a smootheven surface to the casting so it will layflatagainst whatever sceneryframing it might beattached to later. [fyou have enough stonesections in a series, you might want tonumber into the back of each casting foridentification.

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FIG. 13To make a casting, first moisten the mold

with water and tap out any excess so it’smerely damp. Add enough mixed plaster, asoupy mixture, to cover the inside of themold. Vibrate the mold so ‘any air bubblestrapped in the plaster mix will rise to the sur-face and be released. A good method isshown here. A piece of thin plywood is an-chored with one hand to a table edge whilethe overhanging portion is gently tappedwith the other hand. This causes the mold,resting on the plywood, to bounce repeatedlyand thusfree trapped air. Be careful, tappingtoo vigorouslycan cause the mold to end upon the floor! Add more plaster to fill themold slightly to excess. Repeat vibrating ac-tion a last time.

FIG. 15

To illustrate a typical application for the stone castings, we see here scrap plywoodshapedinto forms to be covered with stone for a pair of bridge abutments.

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FIG. 16Here we see the mating feature of the stone sections is somewhat

defeated where angled corners are encountered. It was not consideredworthwhile creating patterns and molds for this one application. In—

stead, as can be seen, pieces were trimmed to shape and thefew stonesat the corner that have been smoothed in cutting can be etched with aknife point to resemble surrounding stone. Any slight irregularities injoints should be carefullyfilled with wet plaster.

FIG. 17

This arrangement has varying stone sizes,an irregular pattern, and no uniform courses.More important, these examples show theadaptability of such interlocking components.These were created for a specific structurefoundation but they are not limited to this oneapplication. The time spentfor their develop»ment was considered well spent, knowing theycould be adapted in varying ways for otherstructures, retaining walls, etc. The repetitivemating feature allows extension lengthwise,stacking row on row expands the height ofawall. All in all, a good stock ofparts to drawupon for future projects.

January/February 1980

FIG. 18Another group of stone sections has been used for this structure

foundation. The lengths of supporting posts under stairs and porchlanding indicate intended earth contour of scenery as it’s formedaround the foundation. Thus it will appear an excavation had beenmadefor the rear ofthe building, hence the needfor a stonefounda—tion in this area.

The abutments when ready are placed andscenery is worked around them. Much of thescenery here is made up of plaster castingsformed in molds as well, but of latex rubber,not silastic. A discussion of this latter workwould require for more space than availablehere - possibly is could be covered anothertime. At this stage, nothing had begun towardthe introduction ofgrasses, shrubs and trees,but obviously these finishing touches wouldconsiderably enhance the scene.

FIG. 19

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FIG. 20After a number of years developing these casting techniques,

learned many things not to do. Many of the problems have beeneliminatedfor the reader. I have included however, these two photosto illustrate afew pitfalls to avoid as related specifically to masonryand stonework.In Fig. 20 we have two segments (upper left) which interlock

satisfactorily each side to comply with irregular stone shapes. The topand bottom edges, being straight, cause an obvious division betweensegments as the patterns combine and expand. Too, using only twopattern pieces, we see a repetitive visual effect showing up amongstonefaces. At lower left we see a correctionfor thefirstproblemwithallfour sides of the pattern being irregular to fit in with the randomstone sizes. Six of these pieces assembled (bottom right) shows we ’veeliminated the obvious division between sections but there is still arepetitive eflect. The ultimate answer then is toform a number ofpat-terns, all with the same configuration (bottom left), but with a diflerentstone placement in each.

FIG. 21In Fig. 21 we see an attempt at brokenfield stone created by 'carv-

ing’ texture into pieces ofplasterwhich were then assembled into thepattern shown (photo top). Not satisfactory and not recommended. In-stead,the desired texture can best be arrived at with bits ofplasterfractured in the manner shown in Fig. 7. Aside from this, the con-figuration of the pattern piece is fine. Once again howeer, when onepattern is used repeatedly (photo bottom)we see the repetitive effectof any prominentfeatures. Once more, the answer lies in several pat-terns at least, eachformed within the same configuration, but with dif-ferent stone placement in each. So muchfor learning!

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Illustrated here is a point notyet covered. Where the repetition ofasingle pattern piece is not objectionablefor reasons previously men-tioned, we see how such a unit is formed to mate with itself: Firstcreate a section ofrandom shape shown as "A ", top left. Next create asecond section (B) so its right side mates with the left side ofsectionHA”. The left side of section "B” is unimportant and of randomshape. The third step, having positioned section "B” to the right ofsection "A ” as shown, is toflll in between the two segments in a man—

ner similar to that shown in Fig. 10. We then end up with a singlestone segment (photo bottom)that will now matewith itselfrepeatedly.

FIG. 23Here is a stone section that carries the single pattern idea to its

ultimate end use. This one (two single units shown at left) will matewith itselfin any position, upwards, downwards, toward either side, orinverted in any of these directions. What I’m trying to say is, there is

absolutely no position in which it can be placed that it will not matewith itself, no matter how you try. Save to say several patterns, withstones arranged differently in each, were built within the same con-fines outlined by ajig, there isn’t space here to go into the varioussteps involved in the complete project. This does illustrate howeverthe possibilities one can achieve in this work.

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