How I Make a Mosaic
From the raw clay
Instead of piecing together a mosaic with small rectangular tesserae (stone, ceramic, or glass pieces), I've adapted an ancient mosaic technique called opus sectile for architectural work. (Here's a photo of an example from the Basilica of Junius Bassus in Rome, AD 331.) I cut the design directly into slabs of moist clay. (I've already worked out the design on tracing paper to scale -- to finished size, plus a percentage to allow for clay shrinkage and grout gaps.) The irregularly shaped sections comprise the actual design. I separate the pieces by glaze color and glaze with Mason stains or naturally occurring colorants (such as copper or cobalt carbonate) in proprietary formulations that allow for single-firing. (That is, I've eliminated the bisque/greenware firing and instead, completely fire my work in one kiln-firing.) I fire a white stoneware or mid-range porcelain clay to cone 6 -- 2200 degrees Fahrenheit. This produces durable, vitreous mosaic tile with extremely low porosity (<1%-2%, depending on clay), impervious to climate.
Edging
Using comparable methods, I design and extrude custom crown-moulding, bull-nose, cove, corner, and decorative trim tiles to specification.
Assembly and Installation
After the fired pieces are assembled into the mosaic design, they can be installed in a variety of ways, depending on application. I mesh the mosaic to simplify installation -- entire sections (typically about 10" in diameter) can be installed at a time.
For interior dry settings, the meshed mosaic can be installed using a latex mastic directly onto plaster or furniture-grade, shellacked plywood. For wet settings (such as bathroom or kitchen, it can be installed over a membrane and amidst field tile. For exterior settings, latex-fortified mortar is used over a cement-based substrate to install into plaster or stucco. The work is then grouted, typically with a latex-fortified, sanded grout for durability.
The mosaic can be bas-relief; that is, a three-dimensional sculptural surface over which light creates highlights and shadows. Elements of the claywork are somewhat more involved, but the overall process is identical.
The ceramic mosaic can be installed by a commercial tilesetter or I can install it myself.
