"Suitable for"


By Leonard Perkins
Retirement, a collection of "rocks," and some inspiration
Produce intarsia copies of paintings and original pictures.

   When retirement after 41 years with the federal government arrived, I was faced with a pile of rocks accumulated over a period of 35 years with the help of six wonderful children who dutifully "assisted" Dad collect.
   After a good deal of study and though a decision was made to have a try at intarsia of rock inlay. The history the development of intarsia by the Romans and later the Italians has been amply covered in several articles in the Lapidary Journal during the past few years. After reading those articles, it seemed reasonable to conclude that if the very civilizations could achieve such beautiful work without diamond saws and grinders, that a rockhound, even one with no formal training in art, could be able to achieve something. At best, I felt my efforts might be appreciate by our children. At worst, the end achievement might enliven some yard sale in the future. If I had known in the beginning how many hundreds of hours would be consumed, I probably would have gone fishing.. But I was soon addicted to intarsia and there was no turning back.

ABOVE: The intarsia of bighorn sheep is made of petrified wood, onyx, jade, jasper, serpentine, and quartz.

Finding the Right Rocks

   I will discuss my method of "constructing" my piece entitled The Last Supper in considerable detail. All my other intarsias were constructed in a similar fashion. The word "constructed" is used because that is what is really done - building one piece is at a time. Of course, you also do quite a bit of praying that everything will come out all right.
   I worked from a color print of Leonardo da Vinci's magnificent painting The Last Supper. This was a paint-by-number project which my wife Bernadine, had done. Working with my wife's rendition, I first made a line diagram (outline) of the total picture. This was done on the unglazed side of a mylar film. The mylar film was then used to make five copies or blueprints. One copy was "shaded-in" with a lead pencil to depict light and dark areas as indicated in the painted picture. In this way, one can get a reasonably god concept of depth and three-dimensional characteristics. These shaded areas also became a valuable tool in selecting the various rocks to be used in constructing the picture.
   The next step involved searching the rock pile for different colors of rocks. Hopefully some of the rocks would be similar in color to the basic painting but that wasn't essential. Obtaining an adequate inventory of various rock colors is a difficult and time consuming job. One needs to visit local rock shops and rock shows, haunt the rock [piles of your friends, and watch for ads in rock magazines. Many color substitutions must be considered, with frequent reference to the pencil shaded blueprints, as well as the painted picture. The selected colors must match of properly contrast and blend into each other in a pleasing manner. If you have no formal training in art methodology, you will have to do as I did.
   All rockhounds know that it is not possible to tell what is on the inside of a rock without opening it up. The first slice should be cleaned with acetone and sprayed with a fast drying lacquer. Now you can see the true color and nature of the rock and envision how it will look in the finished picture. When all the selected rocks have been identified in this manner, imitate these colors as close as possible on another copy of the blueprint using crayons or ink pens. The blueprint should be colored lightly so as to not obliterate the blueprint lines. When satisfied with the colors selected, enough slabs should be sawed to fulfill estimated needs. The slabs should be at least 2/16" thick and as near to possible the same thickness.

Constructing the Frame

   The next step was to construct a frame for the picture. I decided to encase the finished picture in casting resin because I wanted to use a modern technology that would be very durable. It would also help eliminate the difficulties in undercutting when lapping sections of the picture with rocks of various degrees of hardness.
The frame bottom was made of ½" outdoor type plywood, good on both sides. The sides of the frame were also made with ½" plywood strips. The side boards should be deep enough to permit nailing to the frame bottom and also extend above the rock inlay to permit the finished picture to be covered with approximately 1/8" casting resin. The sideboards were covered in masking tape before they were tacked to the frame bottom. This will assist in breaking the strips away fro the casting resin when it is cured. The frame bottom becomes a structural part of the finished picture.
   When the frame is assembled, the blueprint which was colored to imitate the rocks selected for use should be affixed to the frame bottom with several dots of rubber cement. This will minimize movement of the print during placement of the rock pieces. This blueprint will be a master guide to follow in all subsequent assembly operations.

The first intarsia made by Mr. Perkins, entitled The Last Supper, is 33 inches by 16 inches, and is made up of such materials as onyx, petrified wood, and sandstone.

Creating an Intarsia

   The section of the picture selected for the initial "cutouts" and assembly is a matter of personal choice and may be different for each project. In the case of The Last Supper, I selected to start with the section containing the table top and side. The top and side are made of onyx separated by stripes of alabaster into five sections. The center section of the table top was cut out of the blueprint and became template no. 1.This section of table contained a number of items, such as wineglasses, loaves of bread, and hands. These were numbered and cut out of template no. 1. The template was then glued to a slab of onyx and the cutout area for the inserts "inked-in" with a permanent ink. The cutout portions of template no.1 representing wineglasses, loaves, and so on were also glued to rock slices previously identified for these inserts.
   The next step involved the use of a trim saw to cut each piece within about a 1/16" of the template. A 6" diamond grinding wheel was used to grind each piece (as near as possible) to the exact size of the template. This is a slow and tedious task and almost impossible to do without a great deal of patience. It is best to avoid chipping the edges as much as possible. It is also advisable to leave the edge with a slight undercut, as this will permit use of small diamond tools for achieving closer fit when the pieces are assembled.
   At this point, you will have a number of small cutouts and a table top marked with ink where these cutouts belong. Cutting out these ink sections was done with small diamond drills, diamond keyhole routers, and various shaped diamond and Carborundum points. Don't feel bad if this takes a while because it will.
   With the proper holes cut in the table top, the wineglasses and other items were fitted into the holes and glued. Through trial and error, it was found most efficient to place the table top on a piece of mylar film placed on a smooth surface. The inserts were then places in their respective places (face up) and affixed with a small drop of instant glue. The mylar film prevents the glue from running down and sticking to something it is not supposed to. Ina matter of second, pull the mylar film off the bottom, turn the whole section over, and, holding it in the air at a slight angle, insert instant glue so that it runs and seals each joint. Properly applied, the glue will fill the joint void but will not run out the other side where it can be very messy and has to be removed.
   The first completed section of the table top should be done. If the rock slabs were sawed to the same thickness, the top of this section should be even. My 30 year old slab saw is, however, very independent and rarely produces two slabs with the same thickness. Therefore, it was necessary to lap each completed section to achieve a reasonably even surface. Once this is done, place this section on the appropriate blueprint lines which were previously placed in the bottom of the frame. It is advisable to use a small amount of rubber cement to affix the section temporarily to the blueprint. This becomes a stabilized anchor and facilitates placement of subsequent sections in the frame.
   A reminder: work in a very well ventilated place to prevent breathing I the fumes. Also, don't forget to keep the rocks damp at all times when working to minimize rock dust.
   The rest of the table top and side were completed in the same manner as described above and placed in the frame on the appropriate blueprint lines. These table sections represented a fairly large "block" of the total picture. Envision at this point the completed picture which will be composed of a number of blocks or sections which must be glued together so the total picture can be lifted from the frame for pouring the casting resin on the frame bottom and the picture placed back in the frame for subsequent pours to completely encase the picture.
   A decision was made to glue the table sections to each other to represent the first major "block." At this point, the various table sections will have been lapped to a reasonably even surface but various sections may not be even with each other. To correct this situation, paper shims were cut and placed under the edge of adjacent sections until they were even. A few drops of instant glue were applied to the top of the seams to provide sufficient strength to the joints so the whole table "block" could be gently lifted up and, turned face down, and instant glue applied to the seams as explained previously in gluing the center section of the table. I used Hot Shot Cyanoacrylate Accelerator Spray to expedite the setting of the superglue.
   The table "blocks" was then placed in the frame. If everything has been done according to the blueprint outline, it will fit where it should. Again, I found it was wise to anchor this "block" to the blueprint in the frame with a few dabs of rubber cement so it would not shift during further assembly of the picture.

Finishing the Intarsia

   The next step was the arbitrary marking of one of the unused blueprints above and below the table, into sections approximately 8" x 5". My objective was to "construct" each section separately and then assemble al the sections in the previously prepared frame. Where possible, the arbitrary section lines were straight lines, but in a few instances it was more practical to follow the outline of a particular part of the picture.
   After the blueprint had been marked as indicated above, a decision was made to start constructing the center section above the table first. This section contained part of the figure of Christ, the background windows, apart of the rear wall, and the upper portion of three and one half disciple figures. There are twenty-two different pieces in the head and face of Christ. I numbered and cut them out of the rock slabs selected. Most of the smaller pieces had to be glued to nails or wood pins in order to be held. Of course the glue did not always hold and maybe an eyebrow would fly away. It was fruitless to look for these wayward pieces, so I became quite philosophical and simply cut another specimen.
   The eyes and other face segments were assembled first, orienting the small pieces to correspond with the lines on the blueprint before gluing. All the face needed now was hair, a beard, mouth, and a neck, all properly oriented to the lines on the blueprint and glued to each other. The gown, robe, and hands were next. Do them one piece at a time. There are 51 pieces in the figure of Christ.
   The figures of the disciples, the windows, and background wall in the center section above the table were finally completed and ground even on a 12" lap wheel utilizing 100mc silicon carbide grit initially; then 220 and finally 400 grit. Where softer rocks were intermingled n a section, the lapping operation was started with 220 grit to minimize undercutting. This section was then placed in the frame on the upper blueprint lines.
   All of the other sections above the table were completed in the same manner as the one described above. Then sections below the table were treated in a similar manner. When all the sections had been completed and placed on the frame, paper shims were used where necessary to make edges of adjacent sections even with each other. The sections were glued together as described above in gluing the table sections. Turing the frame upside down and letting the picture gently fall on another piece of plywood minimizes the risk of the picture not holding together when lifted out so the resin can be poured in. The initial casting resin (about 1/8" deep) was then poured in the bottom of the frame and the picture was slid into the resin. The resin was allowed toset before proceeding with the rest of the pour.
   Pour the balance of the resin to encase the picture and frame totally. The normal practice used on making a rock coffee table, utilizing the mylar film technique for the final pour, achieved a glossy finish.
   All told, the construction required approximately 1500 hours of effort. I must have enjoyed the effort because as soon asit was done, I started on the next picture and kept going. All follow the same basic procedure as outlined above.



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