A Lost Art Form"
by Conrad Grundke
Learning Commesso, Part
is a relatively unknown art form, Part I of assembling the picture
"Mountain Retreat", will discuss some general tips and techniques
for making a commesso/intarsia. You will want to keep these in mind when
you begin to assemble the picture in Part II. You can also refer
bafck to them as you move on to more challenging commesso/intarsia projects.
Tips & Techniques:
tips should be considered when selecting, cutting and fitting the pieces
in an intricate "Commesso."
1. Picture selection
all pictures lend themselves to becoming "Commessi/Intarsias."
With experience one can predict the difficulty a picture will present and
this is best developed by starting with simple "Intarsias," like
the one in this article, and then progress to more difficult ones with time.
colors and textures may dictate the picture selection. Bright yellows, blues
and reds are difficult to find and the picture may not have the impact desired
when the compromise is made with stones having duller colors.
pictures will stress the stone selection because larger pieces are needed.
These are not always easy to obtain. Smaller pictures reduce the need for
larger slabs, however, smaller pictures require more precise fitting. You
must weigh these two options.
Scanning the stone patterns into a computer
and manipulating them can give the artist an idea of how the finished
piece will look.
2. Picture Generation Using PC:
a. I have
found that my Personal Computer has made a major impact in the way I select
my picture, stones and templates. After generating a line drawing by either
tracing or freehand drawing, I scan the image into my computer and create
an Adobe Photoshop file from which I can manipulate the working drawings.
the image/image size options I can generate any size picture up to 8 ½"
x 11" and make as many copies as needed using my printer.
question that is always difficult to answer, is, "How will my picture
look with the rocks that I have selected?" If you started with a colored
picture and you can select rocks that exactly match the original color and
texture, you already know. In most cases, the rocks you select will vary
considerably from the original.
I select my slabs, I place the individual slabs on my scanner (with special
care to not scratch the scanner glass) and scan the image into my computer.
Again I put it into an Adobe Photoshop file and by selecting an area of
the slab I can "Edit/Define Pattern" to store that color and pattern
onto my hard drive.
the line drawing in Adobe Photoshop, I then select the area where that slab
is to be used using the "Magic Wand Tool."
the area is selected, I then "Edit/Fill/Pattern" using the selected
pattern, which is the slab I have selected for that area, and then fill
the area with the actual rock pattern.
this process for each of the different sections, I can create a colored
rendition of the final picture with a very close approximation to the color
and pattern of the selected stones. Using this technique it is easy to try
different slabs and patterns for the final desired effect. Fig 1 is a computer-generated
picture using this process.
3. Stone selection:
most critical part of a picture is the selection of the proper stones. This
is the one area that cannot be compromised. A viewer's mind will forgive
inaccurate fitting of the pieces, but the mind will not replace inadequate
stone selection for either color or texture. Pattern and color are very
important. Each stone must closely resemble the object it represents (i.e.,
sky, stone wall, leaves, grass, etc.) in order for the picture to look right.
Also pay attention to light and shade, using slightly darker material for
the areas in shade. You may go through many pounds of rock before finding
just the right ones.
start a "Commesso/Intarsia" until you have selected all the stones
needed for the picture. Not having the proper stones to start with will
result in inserting what might be available rather than what is needed when
the time comes.
you purchase slabs or cut your own, try to make them of approximately the
same thickness to avoid having gross variation on the back. Slabs 1/8-5/16"
thickness will be most common with ¼" preferred.
Italy a Commesso/Intarsia Pietre Dure is comprised of stones of the same
approximate hardness. We do not have that luxury and many areas of the country
will find certain colors hard to find. In California, white stone is generally
Howlite with a hardness of 4.5. Most Howlite will not take a high polish
and the resultant completed picture will be finished to the best polish
of the least polishable stone, quite often in our case Howlite.
a Commesso/Intarsia ages, many stones will change color due to viewer handling,
cigarette smoke, and various oils and chemicals in the atmosphere. The harder
the stone, the less likely that they will change color, although many pieces
of rose quartz will fade drastically over time. To circumvent this effect,
I use an automobile wax to protect the picture when it is completed. Carnauba
Wax is my preference. In the past we had used a Krylon spray matte finish.
This does yellow and peel over time.
4. Suggested Possible Stones:
(#21) - Norwegian Sunset Marble
(#12 & 20) - Birds Eye Serpentine
(#10) - Brecciated Red Jasper
(#13) - Agate
(#11) - Rhodenite
(#14 & #17) - Mallachite/Azurite
(#15) - Picture Jasper, w/o the picture
(#16) - Brecciated Jasper
Mountain Side (#9 & # 18) - Howlite, very dark piece with mostly matrix
Mountain Side (#19) - Howlite, light piece with slight matrix
(#17 & #17a) - Red area from Pidgeon Blood Agate
Steeple Roof (#2 & #6a) - Light Red Jasper
Steeple Roof (#6b) - Dark Red Jasper
Eave (#3c) - Black Basalt
Steeple & Church Wall (#1 & #5) - Slate
Steeple & Church Wall (#3 & #5a) - Petrified Wood
(#1a, #1b, #3a, & #3b) - Abalone Shell or Paua Shell
Tip (#21a) - Basalt