Working with Large Mosaic Enamels

An enamel of any size can be produced by working sectionally. I cut copper sheet into irregular shapes to enhance and strengthen a design and to give the illusion of a large single piece. The pieces are mounted on a single sheet of 3/4″ marine plywood. This method requires a worktable large enough to lay out the full-scale work. I have made many panels by this method, the largest being 5″ x 7″, which is the size of my worktable. The large panels are hung with the tow-piece brackets used for wall cabinets.

I first design a marquette about one-third the size of the planned enamel mosaic. It is an accurate full-color depiction, to scale. Then I make a cartoon (a line drawing) to plan the cutting of the sections of the mosaic and number each piece. The cartoon should be based on the abstract design of your composition and divided into smaller pieces as necessary. Avoid long, thin shapes, C shapes or S shapes and highly irregular shapes. With a pantograph, I enlarge the cartoon to full size on wide butcher paper. I then make any necessary corrections and number the pieces to match the first cartoon. Each piece should be able to fit comfortably in your kiln with a 2″ margin on all sides.

I first work on the plywood sheet to which the enameled sections will be attached. Wood sealer is applied to the back and edges of the plywood sheet. When dry, square (3/4″ to I") aluminum tubing is cut to form an X shape to be screwed to the back to ensure the rigidity of the panel. Allow clearance for the frame. These aluminum tubing pieces should be drilled to accept wood screws that will go through the tubing and halfway through the plywood. The X shape is positioned on the plywood and screwed in place. The plywood is turned over to accept the tracing of the cartoon and then the copper pieces, The full-scale cartoon is placed on the plywood and fastened in place on two sides with drafting tape. The cartoon, including the numbers, is traced onto the plywood with a fabric marker wheel and carbon paper.

Allegory-Silicon Valley: 5′ x 7′ copper, foils. enamel.

I buy large pieces of 18 ga industrial scrap copper, cold-rolled, annealed if possible. With a Beverly shear, an electric shear or even a jeweler's saw, I cut the copper after I have cleaned it to remove any oil or dirt. The cartoon pieces are glued with rubber cement one at a time to a piece of copper. After the copper is cut to shape, its number is put on the back with an electric engraver. The rubber cement is removed from the back of the cartoon piece and the cartoon piece is saved in a folder for reference. The copper pieces are flattened with a rubber or leather mallet on an anvil.

I clean the metal in a pickle of the standard Sparex solution to remove the copper oxide, rinse well and scour with steel wood and detergent. When the water sheets off the surface, the metal is grease-free. I wear latex or plastic gloves to protect my hands and to protect the metal from fingerprints.

I use primarily leaded enamels from my inventory in 80 mesh and 150 mesh. I use ISO mesh when the piece requires four or more coats. I apply the enamels by either sifting or wet packing and use various techniques depending on my design.

For the base coats, I use liquid hard flux with backing enamel for counter and 80 mesh medium flux sifted over a solution of metho gum on the front. The gum I use is carbo - metho -cellulose (CMC) from Hercules Powder Co., Wilmington, Delaware-, 52 grams to make five gallons. To make it into solution, I dissolve all 52 grams in one gallon of distilled water and then mix in another four gallons of distilled water.

Smooth, even coats of counter enamel on the back will discourage warping. The irregular shapes and larger pieces are fired on the "bed-of nails" stilt. My kilns have a pyrometer and a rheostat. The kiln is preheated to 1550 Degree F before placing the piece in the center of the kiln with small areas or angles nearest to the door, away from the elements. I check the firing by opening the door a crack. After the piece is fired, it is weighted with a press plate on a warm marble slab to keep it flat. The hard fusing enamels are fired first, the opaque reds and oranges added close to the last firing.

After every firing, the loose scale from the edge of the copper piece is removed with a medium-cut metal file. Each piece is placed on the cartoon as I work. For efficiency, I enamel all pieces of the same color first. They are sifted, fired and, when cool, are placed where they belong on the plywood. I plan all the colors initially. Wherever I plan to use silver foil, I sift and fire 80 mesh medium fusing white on that area. The foil is cut and placed on a sheet of static preventative before being positioned with diluted gum; it is fired when dry.

The biggest problem with enameling copper is that the copper grows with each firing. The copper expands in the heat, and the glass solidifies before the copper has returned to its original size. Therefore, I use my cartoon pattern to check the size of each piece. If any edge needs to be ground off, I trace that edge with a permanent marker. I grind as needed and keep each piece its proper size.

My motor has an exhaust hood for an expandable rubber wheel with a coarse (80 grit) wet-or-dry abrasive belt. The wheel is kept wet with a spray bottle of water to prevent heating and dust. I wear a particle mask. I do not grind or stone the enamels for a smooth finish: I feel the irregularities of enamel thickness enhance the visual impact.

When all the pieces have been well developed, I climb a tall stepladder to look down on the work as a whole to see where color value changes are needed. The design grows, as an easel painting would develop. I keep complete notes on each piece of the cartoon pattern.

For indoor installation, I use hot glue to attach the enamel pieces to the plywood. Next, I apply non-sanded grout, formulated for kitchens and bathrooms. Oxides are added to the grout for smooth blending from one section to another. The grout is applied with a small artist's spatula-, I clean any excess as I go. As a final step, the grout is covered with grout sealer. The mosaic is then ready for framing and/or installation. The pieces must be set and grouted with mortar if the installation is to be outdoors.

I have focused on the way I work today. Tomorrow may bring a different story, so don't be afraid to be creative.

Excerpts from the book:

Enameling with Professionals
A unique book for everyone interested in the art and techniques of enameling
By: Lilyan Bachrach - Copyright © Lilyan Bachrach 2004
ISBN 0 9719252 0 8