by Charles H. Smart

Charter Member of the
Minnesota Mineral Club
4737 Balisdell Ave.
Minneapolis, Minnesota

   The author, Charles H. Smart, was the winner of the Lapidary Achievement Award plaque at the 1963 convention and show of the American Federation of Mineralogical Societies, held at Oklahoma City in June 1963. MR. Smart's "Baldpate" duck intarsia appeared o the cover of the Lapidary Journal for January 1963. Another, of a "Mallard drake" will appear on a future cover. Each is a masterpiece of careful selection of design, color of material and meticulous workmanship.

Wood Duck

   The purpose of writing this article is to furnish information on the making of stone pictures. Most of us have a desire to know how things are made even though we may not have the urge nor the skill to do them ourselves. Please keep in mind that the information given has been gathered fro only one man's experiences. There are other ways, perhaps better ways of making an intarsia, bit the following described processes have produced good results for me.
   There are two basic ways of cementing together the many stone pieces that are used in making mosaics, intarsias and stone pictures. One of the ways is to make the picture with its face down. The pieces are cemented to each other face down o waxed paper covered work board. The uneven and unfinished surface of the stone is up. The waxed paper is used to prevent the cement from sticking to the work board and will allow the finished picture to be removed later on. An important advantage of the face down method is that the pieces of stone may vary quite a bit in thickness. This uneven back surface is later covered with cement. The method is widely used. I believe it is the accepted method of making beautiful intarsias now being produced in Italy.
   The second method of making the stone picture is to cement the fitted stones face up to what will be the permanent base. Several materials may be used for the base. I have used Plexiglas in all of my work and find it satisfactory. It is light in weight, very strong, easily cut to the desired shape, has a low expansion factor and if roughened a bit with 220 grit cloth provides a surface to which the cement will hold indefinitely. I prefer the face up method for a number of reasons. It is easier for me to accurately fit the many pieces of stones. Progress from day to day can be noted. I know that I am less likely to use an inferior piece of material, or allow a clash in color harmony. There is less likely that a misfit will get into the picture. The pattern of lines in the stone should contribute to the flow of motion. This is especially true in the flying ducks. Since it usually takes me from five to six months to complete a picture I just could not wait that long to see what the other side looks like. Then when the picture is finally turned over imperfect stone or flaw might be right in the middle of it. Such a disaster is quite unlikely to happen if you can see from day to day just what stones are being fitted and you can do this with the face-up method. There is this disadvantage in the face-up method. It is very necessary that all the pieces of stone be cut or ground to the same exact thickness before being cemented into place in the intarsia. Even so, I think the face-up method is he better way.

Fig. 4

   Fig. 4. - If someone should accidentally turn on this trim aw the author and his clothing would be a mess, for as you may have observed there is no splash guard over the saw and no apron on the workman. The splash guard was removed so that the offset in the table can be more easily seen. The apron would be unnecessary anyway for the man is not really working.

   The idea to make an intarsia of a duck in flight had been in my mind for several years. The duck that I had selected was the very colorful Mallard drake. I also knew that the project would be quite pretentious and difficult. I knew too that I should try the method of procedure on a project less exciting. The insignia shown in Fig. 1 was the practice project. I made it, using the patriotic colors of red, white and blue. A ring of black petrified wood was out on the outside. I found the insignia not to easy to make and that it took more time to do than I had expected it would. The result was gratifying however. The lessons learned were to help later and I found that a good tight joint was possible. The "Mallard" was made back in 1958. The "Wood Duck" was made next and the "Baldpate" was completed just a year ago. There was considerable improvement in workmanship from duck to duck as I gained in proficiency and experience.
   I realize that a considerable portion of the information included in his articlewill be old stuff to many readers, but since our readers include both the informed and the uninformed, I feel that some of information will be of use to all.
   Reference will be made occasionally to the "Baldpate" intarsia which appeared on the cover of the January issue 1963 of the Lapidary Journal and to the "Wood Duck" which is on the cover of this issue.

. . .. . .

. . . .. . . .. . . . Fig. 1. .. . . . .. . ... .. . . .. . . . .. . . .. . . .. . . . Fig. 2. . . .. . . .. . . .. . . .

   Fig. 1. - This intarsia was the practice project. It was made before any of the duck intarsias were started. I found it more difficult to make than I had expected.

   Fig. 2. -A colored picture, chosen to meet your ability, will very likely be the guideto your first stone picture. The method shown in the above drawing will indicate howthe original print may be used to produce a working drawing that will meet your conditions.

   The first step in making a stone picture is to select the subject and make a work drawing the exact size of the finished picture. I knew I wanted to make as my second intarsia another duck. The first one, the Mallard, was shown jumping off the water in extreme alarm. I wanted the second duck to express just the opposite mood; it was shown coming in for a landing nd without fear. I think the Wood Duck express this mood delightfully. The webs are down and the wing tips are in an alighting maneuver. The "Wood Duck" was a part of a colored picture appearing on a calendar; subject matter by R.C. Bishop. Since the picture of the duck was not quite the right size, the method shown in Fig. 2. was used to enlarge it slightly. This method of making a copy may be used to either increase or decrease as you wish. Use a sharp pencil and work from square to square. I use a good grade of white mechanical drawing paper. It is stiff enough to be used for patterns when the drawing is cut apart later. The red-headed woodpecker would make a fine subject if any of you should be inclined. It does not express motion that I like in an intarsia but it does have an attractive color contrast. The black and white print does not bring out the brilliant color but a colored print could be easily obtained to work from. There is an opportunity too, to express one's skill in the amount of detail included in the feathers of the wing, back and tail.
   The next step is to get the material together before starting the project. I have enjoyed the rock hobby for many years and have accumulated quite a rock pile. Most of the material I used came from the rock pile. Some were obtained from friends. Listings of dealers in this magazine, especially the April issue, the Buyers guide issue, helped out when a very special slab was needed. Al the material used in this type of work must be opaque or very nearly so. The backing, Plexiglas in the ducks, must not show through. The material should have a good color and pattern. Color will attract attention and the pattern will put life and motion into the picture. The way he material is cut into slabs will often give the desired effect. Notice the pattern on the end of the chunk of petrified palm wood shown at A. Fig.3. The cellular structure, when cut across the grain of the wood, produces a definite arrangement of dots. It will be seen that the dots become elongated ovals when the palm wood is cut at an angle. The pattern was idea; for the feather effect that was needed in the under throat and lower neck of the "Baldpate." In B. Fig.3 the angle sawing gave what is known as the herringbone pattern. Petrified wood cut this way was used many times in the three duck intarisas. The herringbone pattern cannot be used unless the end grain shows a wavy pattern of the annular growth rings. The greater the angle at which the rock is cut the more elongated the pattern becomes. Slabs 3.5 mm thick were used in all of the intarsias.
   The following materials were used in the "Wood Duck." The bill is yellow petrified wood, with white datolite and black petrified wood trim. A fine line of agate is at the upper end of the bill. The head is crowned with curved pieces of bloodstone, jasper, jade and datolite. The cheek is chrysocolla. The throat is datolite and black jade. The upper breast is jasper. The lower breast is howlite. The tail fan is black petrified wood. The legs are rhyolite. The upper edge of the wing is petrified algae. The next row is petrified palm wood. The remaining feathers are petrified wood, herringbone pattern. The white on the lower edge of the wing is datolite. The eye was cut from a Lake Superior agate.

Fig. 3

   There are 198 separate pieces of stone in the "Wood Duck." It took about 400 hours of actual work spread over five months of time to complete.
   The preparation of the backing was next. A piece of Plexiglas about ten inches square equaled the size of the picture. I have used Plexiglas three-sixteenths inch thick in all the ducks. The polished surface of one side of the Plexiglas was thoroughly sanded with 220 grit cloth. The cement will adhere better and a pencil mark can be made on it. A piece of tracing paper was placed on the drawing of the "Wood Duck" and just its outline was traced. Since I do not wish the backing to show at the edges, I make the backing one-sixteenth of n inch smaller all around than the finished picture will be. I then cut out the tracing, but instead of cutting on the tracing line I cut inside the tracing line, that one-sixteenth of an inch. The cutout is then put on the sanded surface of the Plexiglas and marked all around. The Plexiglas is then ready to be cut to shape. I have found the quickest to do this is on the grinding wheel. I have a 10" wheel, 80 grit and another one-fourth inch thick. It will cut away he excess Plexiglas in a hurry. The Plexiglas must be placed flat on the slab rest in front of the wheel. More about the slab rest later. Some sawing and filing will be necessary to remove the Plexiglas the grinding wheel could not reach.
   We should devote some space to the machines we shall use. The trim saw Fig. 4 is one grand little work horse for the lapidary, especially in the making of stone pictures where hundreds of separate pieces of stone may be used. You will note that the table is not on the same level all the way back. The front half is on a level with the saw arbor. The slab being sawed is then able to meet the cutting edge of the saw squarely and a vertical cut is obtained. This will enable cuts clear into sharp corners without undercutting. When this saw was built years ago none like it were on the market; they may be purchased now. The depth of the cut is limited to a bit less than half the diameter of the saw blade. I use a saw 6" in diameter and .040 in thickness. The thin blades are not rugged enough. The thicker blade will take the pressure put on the saw by the slab much better. We must remember that in vertical cutting the pressure put on the slab is distributed over a very small portion of the periphery of the saw blade. When pushing a one-eighth inch thick slab against the saw only one, or at the most two teeth, must do all the cutting. It is easy, by applying too much pressure, to damage the blade and start it to bumping. I find it necessary quite often, to remind myself to take it easy as there is no hurry and to remember that having fun is one of the main objectives of every hobby. The trim saw can save many hours of grinding. Always saw with the top side of the stone up. Saw close to the line on the convex curve. Make at least three cuts. One the concave side straight cuts to the center of the curve from both ends will remove a V shaped piece of stone. Much of the remaining material on the concave side can be removed by making a series of cuts into, but not touching, the marked curved line. Make any cuts close together and break off the material between the saw cuts with a pair of pliers. The curved pieces of stone used on the top of the head of the Wood Duck as well as the feathers in the wings were roughed out in this method.


Previous - Next

back to top