"Discovering A Lost Art Form"
by Conrad Grundke

Learning Commesso, Part II

   In Part I the preparation and assembly techniques for making the "Mountain Retreat" commesso/intarsia were explained. By applying those tips and techniques and using the tips on epoxying in this part, we can now begin construction of the piece itself. A beginner can expect to take a month to complete this project once the stones have been selected. With experience, this can be cut down to less than two weeks.

7. Epoxying:
   a. Except for jewelry "Intarsias," I do not use one of the "Super Glues." The set-up time is far too short. At least 98% of all of my seams are joined using a Devcon 5 Minute Epoxy, which allows me to work on the piece within 10-15 minutes. This epoxy is one of the few clear epoxies that does not yellow when it dries and is strong enough to hold an entire picture together. When I have several large assemblies to glue together, usually the last step in completing the picture, I will use a 330 Epoxy. This gives me a bit more time to get the pieces aligned before the epoxy sets up.
   b. Only glue two pieces together at a time, if possible. Trying to glue more pieces simultaneously is difficult and can present problems.
   c. Glue the pieces together face down on two (2) layers of wax paper placed on the layout board. Being frugal here and using only one piece of wax paper will result in the front of a beautiful "Commesso/Intarsia" glued to a layout board.
   d. In the past, several methods were used to hide the fit in a seam that was not quite adequate. Crushing rock in a mortar and pestle from one of the stones being glued and mixing it with the epoxy was tried. This usually resulted in a tricolor "Commesso/Intarsia." One color for each of the two stones and a third for the resulting ground up material. Then a colored pigment was tried mixing it in with the epoxy to color the epoxy. This introduced a foreign substance that doesn't agree with the epoxy and the epoxy usually will not harden and remains rubbery. In addition, unless you are good at mixing colors you can still end up with a tri colored piece. I strive for not having seams that need to be aided in this manner. I have used a filler in my epoxy that has purpose at times. By adding 80 mesh colored enameling frit to my epoxy I can color my epoxy for seams that I want to bring out, like the lap between boards in a barn. The frit does not effect the hardening of the epoxy and, in fact, increases it's strength.
   e. I mix my two-part epoxy on an old extra slab of stone. If I want it to set up faster than normal, I'll warm the slab under a heat lamp before I mix the epoxy. My preferred tool for mixing the two parts of the epoxy is an artist palette knife. This minimizes the generation of air bubbles within the epoxy and ensures a thorough mixing. Most problems with epoxy results in the epoxy not getting hard and remaining rubbery. There are a number of reasons for this; such as moisture, humidity, foreign substances like oil, and inadequate mixing of the two parts.
   f. When two pieces are to be glued I take up some of the epoxy on my finger and wipe the edges of the two stones to be glued. Then I apply additional epoxy with the palette knife.


Glue the pieces face down on the layout board, using steel push pins and a wood fulcrum to hold them in place, while the epooxy sets up.


   g. Placing the two pieces face down on the wax paper covered layout board, push one side up against the raised edge moulding in the corner of the board. The stones should be held down onto the board with steel pushpins. If you need to apply pressure to force the two stones together, I have used small strips of wood (similar to a square Chinese chop stick) as fulcrums to apply a constant pressure against one piece. Pushpins can help to hold the fulcrum against the stone. See Fig 8.
   h. After gluing two pieces together, always lap the front surface flat on a lap wheel. This will ensure that you do not assemble a whole picture and find some small section is recessed and you have to lap the entire picture down.

8. Assembly Process: - "Mountain Retreat"
   a. In the assembly drawings pieces like 1a & 1b should be assembled as unit 1 before attaching to unit 2.

. . . . . . .
Begin the commesso/imtarsia by making the church as a separate assembly.


   b. Begin by making the church as a separate assembly using the church assembly sequence, Fig 6. The tip of the church will be assembled into the sky as a last step before gluing the sky in place. I then draw the slots and outline of piece #1 onto the stone selected for the sunny church wall. Cut slot #1a into piece #1 and fit and insert a piece of mother of pearl or abalone shell into this slot. Epoxy the window in place.
   c. Then cut second slot #1b and insert another window. If you try to save time by cutting both slots in a soft stone it is possible that the piece in between will break out. These slots can be cut with a "nibbling saw", described above, a diamond-coated wire in a jewelers saw, or a band saw.
   d. Cut the left and bottom edge of piece # 2 and epoxy pieces #1 & #2 together. Leave the bottom of piece #1 extend beyond what is needed for the finished piece. It will be cut off later when fitting the wall, piece #11.
   e. Lap the front surface flat.
   f. Assemble #3, #3a, #3b & #3c in a like manner. Fit and epoxy on #3c and then fit and epoxy assemblies #1-2 & #3 together.
   g. Lap the front surface flat.
   h. The church steeple is then assembled. Create the clock with the hour and minute hand as an assembly #4. Drill a small hole, 1/8" into the sunny steeple wall material. Enlarge it to the oval shape for the clock. Cut and fit the clock face into this oval opening and epoxy it in place.
   i. Fit and epoxy parts #5 and #5a together. After this is done cut the top two arched surfaces to the desired shape. Fit and epoxy #6 and #6a together. Fit assemblies #5 & #6 together and epoxy. After the epoxy is set up grind the top of the steeple roof to the desired shape. The steeple is then ready to be fit and epoxied onto the church body to complete that assembly.

   j. Once Again, lap the front surface flat.


9. Assembly Process Concluded:
   a. Once the church building has been completed, the remaining pieces of the picture can be fitted and epoxied together, one at a time. (See Part I for the assembly sequence.) When fitting the next sequential section, only cut the sides of the piece that will be epoxied to the existing assembly. Remember to lap the front surface after each new piece is added.
   b. As you add pieces 10 - 14, do not cut the edge of the picture at this time. The final outer edge of the picture will be trimmed down once the entire assembly is completed.

. . . . . . .

   c. When you reach sections 17 and 17a, this can be created using two separate stones fit and epoxied together, or if you can find a stone with the necessary pattern, this can be created out of one piece. This area of the picture represents some bushes or trees (17) with some flowers or blossums on the top (17a).
   d. In this picture it is helpful to find a rock that will imitate a rock wall for section 16. This can be difficult to find. Some stones to consider are brecciated jasper (as was used in this picture), petrified dinosaur bone, turetella and petrified palm root, cut at an angle.
   e. Section 21 will be the longest length you will have to fit. This will be a major challenge, since there will be times when you will grind too much in one area, affecting the fit in another. I used a thin section of soft marble for the sky. In the process of fittng 21 into pieces 10 and 12, a piece of the sky broke off. Normally, I would have cut another piece; however, this was the only piece of marble I had, and as a means of salvaging the piece, I inserted a tree between pieces 12 and 10.

   f. Fit piece 21 next to the lower assembly, but do not epoxy. Next cut the slot for 21a out of 21 and insert the steeple into the sky. Once assembled, 21 and 21a can be epoxied to the lower sections as a single unit. This sequence will ensure proper alignment between the steeple tip and the steeple roof.
   g. Once the picture has recieved its final lapping with 220 silicon carbide grit, the oiuter edges can be marked and trimmed off using a thin-kerf diamond trim saw blade. I then finish the edges with a 8-inch diamond grinding wheel, being careful not to let the edge of the wheel cut into the edge of the picture. Gentle pressure and a slight left-and-right motion across the wheel surface can effectively trim the edges to their final dimension.


4

Previous - Next

back to top