by William Grundke
. . . . . . . . . .
the December, 1981; and the January, February, March, April, may and June,
1982 issues of this magazine, the author presented the series, The Art
of Intarsia. Parts 1 through 7. In this series he began by telling how
to elect a design and choose appropriate gem material. Fro there he progressed
through sawing, lapping, grinding, cementing and mounting methods, then
gave the complete instructions for making a simple intarsia picture, followed
by one with more challenge. Part 7 covered some special techniques to achieve
maximum effects and beauty.
series concerned the making of pictures for framing and display. You can
also use the techniques of intarsia to make interesting cabochons with pictures
or geometric designs. The methods described in Parts 1 through 7 of the
series still apply for sawing and shaping the component pieces. By following
those techniques, it is possible to produce cabochons like those shown in
the color photos. If you have not yet read the series, please be sure to
do so before embarking on a project such as this.
cabochons in the color photos are flat faced. Therefore, the very same procedures
covered in Parts 1 through 7 of the series, The Art of Intarsia,
including flat lapping, will be followed. However, just about all the gemstone
pieces for a cabochon will be smaller than some (not all) the pieces for
an intarsia picture. Therefore, the technique of attaching a tiny piece
of stone to a larger one will be very helpful. You'll find this method described
with Fig. 15 on page 55 of the January 1982 issue of this magazine.
of flat-faced assemblies, some gem cutters prefer to make intarsia cabochons
with traditional domed tops. If you prefer this style, you mast be especially
careful in selecting gem material since more material is ground away form
the edge than form the center of the cabochon. Be sure that gemstone slabs
are of even color throughout. Otherwise, as you cut the dome, you may grind
into another color, ruining the entire piece. Extra time spent in the selection
of material can save you time and grief in the long run.
most craftspersons, it is easiest to make the first intarsia cabochons with
geometric designs. Those shown in Fig. 1 are striking and attractive in
appearance. Surprisingly, they are not as difficult to make as one might
think. However, they do take a fair amount of time and patience.
first step is to select enough material in two contrasting colors - black
and white, for instance. The material must be then sawed into thin strips
with absolutely parallel sides. If you have a machine, such as the Gy-Rock
Preformer Saw, shown and described in Part 7 of this series (June '82 issue),
it will do this job very well. Or, with a conventional trim saw it is possible
to devise a rip fence like those on wood saws. Be sure that the fence is
absolutely parallel to the blade. With a rip fence setup you will probably
find that unless you have very tough gem material, you will break a fair
amount of strips. Discard any on which the sides are not parallel.
all strips to be sure they are all the same width. When you have enough
alternation colors to make the size cabochon you want, cement the strips
together as shown in Fig. 2. Be sure to press out excess cement. Epoxy works
well for the adhesive.
the cement has hardened, make parallel saw cuts perpendicular to the length
of the strips (Fig. 3). These cuts must be spaced so that the resulting
strips are the same width as the original strips. The new strips should
be composed of squares of alternating colors as shown in the diagram.
strips of squares are the cemented together, staggering them so that a checkerboard
pattern is formed (Fig. 4). After the cement has hardened, saw the assembly
to the desired length and cut it into a cabochon.
. . . . . . . . . .
2. .. . . . . . . . . . . ... . .... ... .
. . . . . . . . . Figure 3
and Cementing Techniques
making the pieces for intarsia cabochons, it is especially important to
avoid undercutting. There is no problem in cutting strips for a checkerboard
pattern, but other shapes require special care. If there is any appreciable
amount of undercutting, you may grind a cavity when you dome the cabochon.
I use a Preformer Saw, or a sawing jig like that shown in Fig. 4, Part 1
of this series (Dec. '81 issue), or any other suitable method to cut straight
sides of the pieces.
because of the problem just described, you cannot make bevels on the undersides
of the pieces to form grooves for the cement as discussed with Fig. 16 in
Part II (Jan. '82 issue). Therefore, when the pieces have been pressed together,
only a very thin layer of cement holds the cabochon together. To give the
assembly more strength, you can add a backing as shown in Fig. 5. If you
are cutting for display and competition, use a piece of gemstone, preferably
of the same material as used for the cabochon. If the cabochon is to be
set in a jewelry mounting, the backing can be of gemstone, metal or even
plastic. If possible, make the backing in one piece and attach it with epoxy.
the assembly is ready to cut into a cabochon, scribe the outline on the
face, or attach an appropriate decal to the face, depending on whether you
use templates o decals of cabochon shapes. Experts advise cutting the assembly
face up, just the opposite of the usual method of cutting cabochons. Grind
up to the outline, making the edges perpendicular to face, then bevel the
edges and dome the top.
. . . . . . . . . .
4. .. . . . . . . . . . . ... . .... ... .
. . . . . . . . . Figure 5.
other geometric patterns can be worked into intarsia cabochons. For instance,
you could cut a cross or a star shape of one gemstone and surround it with
other materials. Techniques for cutting shapes like crosses, stars and hearts
are covered in books, such as Advanced Cabochon Cutting (available
at rock shops and from mail-order suppliers).
you have cut a star, it can be put into a circular cabochon. To do this,
cut pieces to fit between the arms of the star. Each of these pieces should
be sawed with two angling sides that match the angle of the intersection
of two of the arms. Be sure that these cuts are accurate for a good fit.
It is a good idea to make these insert pieces oversize so that there will
be excess material to allow room for cutting the circle. Therefore, after
the angled sides are cut, make intersecting cuts, starting at the tips of
the star and running parallel to the radii of the circle. This will allow
you to completely surround the star with a circular border or to cut the
circle down to the tips of the star.
a cross you could cut pieces to fit inside the arms of the cross which would
form a rectangular assembly. Border strips could then be cemented around
this assembly so that the cross would be surrounded by a contrasting material.
back to Part I of this series (Dec. '81), you will find a discussion of
geometric designs. The pattern shown I Fig. 1, Part I is an example of how
you could build up such a design. Regardless of what design you choose,
the techniques covered in the intarsia series apply; build up in units.
the same unit-building techniques apply to the building up of an intarsia
cabochon with a non-geometric picture in it. A good example is the bola
with the image of a cardinal which is shown in one of the color photos.
The body of the cardinal (red jasper) was cut as one piece. To it were added
the black and yellow pieces to form a unit. From there the intarsia was
built up adding branches, leaves, berries and background.
this bola is two intarsias. The cardinal, main branch, some leaves, etc.
are the top part (layer). Other branches and leaves are the bottom layer.
These tow layers were then put together, doublet fashion.
Note: If you would like to make a cabochon like this, the book, Artistry
in Cabochons by Robert Ferguson (also available form our suppliers)
includes a cardinal pattern in several sizes. It also has patterns for many
other shapes, including several animals.
cardinal cabochon is set in a silver mounting that was produced with standard
jewelry making techniques. Note that the dangles on the bola cord tips are
edged with silver strips. I find that stone dangles without such edging
can break apart when they bang together.
note that the dangles are of a geometric pattern. Here three thin strips
were cut and cemented together., then larger pieces of gem material were
added top and bottom. Then the shapes of the dangles were cut.
add some variety and eye appeal to an intarsia cabochon, you can put some
silver into the design. Just cement silver strips to the edges of a nit(s),
then cement the next stones to this silver edging.
is amazing what can be accomplished with good tools and a little imagination.
If you have a saw with the blade mounted on an overarm arbor, such as the
Gy-Rock Preformer, you can set the blade for a certain depth and feed a
gemstone slab along a guide to cut out a groove. Later this groove can be
filled with a single piece stone of contrasting color, or several stone
strips cemented together. With a true-running saw, you can cut these strips
as thin as 1/8". Make up strips of several colors and cement them into
a unit that fits the groove. Strips can be made into striped patterns, much
like the beginning of the checkerboard (Fig. 4). Instead of being mounted
into jewelry, these small intarsias can be displayed like pictures. The
one of the blue jay (see color photo) is an example. Note that it, too,
is edged by silver. This intarsia is displayed on masonite with some special
decoration. To start the decorative process, some trim pieces in various
shapes were sawed from sheet aluminum. Figure 6 is a closeup of one of the
trims. Elmer's Glue was used to attach the aluminum pieces to the masonite
in the pattern shown in the color photo. An emulsion, Hyplar Gloss medium,
was then stippled on quite heavily with a painter's loose camel hair brush,
covering the masonite and aluminum trim. When this medium had dried, it
was covered with a glazing liquid, tinted to suit with oil colors (the type
that come in tubes). The glaze was wiped off with a soft cloth, leaving
it only in the hollows. After this had dries a coat of varnish was applied.
the larger intarsia pictures, cabochons of this type offer a challenge to
the gem cutter. When finished, they can be worked into a variety of striking
jewelry pieces; inlayed in the lids of jewelry boxes, etc.; or displayed
on miniature easels or in frames as just described, to name a few possibilities.