A Tesera mosaic portrait is glass smalti and glazed ceramic tesserae, each 8–14 mm, cut by hand with a hammer and hardie and set in lime mortar on a 12 mm sealed birch panel. It is then grouted, cleaned and waxed. There is no print, no resin and no vinyl anywhere in it.
What is smalti, and why is it cut by hand?
Smalti is glass melted with metal oxides and poured into slabs. We cut it with a hammer and hardie, so each tessera has a freshly broken face that catches the light.
A hardie is a small chisel-shaped anvil. The slab rests on its edge, the hammer comes down, and the piece comes away with a face no machine has polished flat. A finished panel is thousands of those small faces, each sitting at its own angle, which is why the surface reads differently as you walk past it and why a photograph never quite gets the light right.
The tesserae are 8–14 mm across. Within one portrait the size varies, and the detail goes where the photograph has it: the eyes most of all. The whole list of specifics is on the materials page.
Where does the ceramic come from?
The ceramic is fired and glazed by a potter two streets away from the studio, and we cut it with the same hammer and hardie as the glass.
Glass and ceramic do different jobs in a portrait. The smalti goes where the light should catch; the glazed ceramic carries the quieter passages, a coat, a ground, a shadow, so the panel reads as an animal first and as a surface second. The colour in both is in the material, not painted onto it afterwards: in the glass itself, and in the fired glaze.
What holds the tesserae on the panel?
Lime mortar, on a 12 mm birch panel that is sealed before anything is set on it. The mortar is the bed the tesserae are pressed into; the grout fills the joins afterwards; the wax is the last thing to touch the surface.
| Layer | What it is | What it does |
|---|---|---|
| Substrate | 12 mm birch, sealed | A panel that will not warp, with the keyhole hanger and our signature on the back |
| Bed | Lime mortar | Holds every tessera, set the way the basilicas were |
| Tesserae | Glass smalti and glazed ceramic, 8–14 mm | The portrait itself, cut by hand with a hammer and hardie |
| Joins | Grout | Fills the gaps between the pieces and locks the surface together |
| Finish | Wax | Cleans and seals the surface so the glass reads clear |
We say "set into lime mortar the way the basilicas were" because it is literally true: the same bed, for the same reason. Why lime mortar and birch goes into what each of them does.
What is not in a Tesera mosaic?
No print, no resin and no vinyl anywhere in it, and nothing cast. If you can feel grout between the pieces and the panel has weight, it is mosaic.
- No printed board or photo tile under the glass
- No resin pour over the surface
- No vinyl or transfer lettering
- No cast or moulded tesserae: every piece is cut from a slab or a tile
- No machine: a machine has never touched the panel
Buyers write to us about this more than anything else. One of them put it as "glass and clay, not a print": it has weight, and you can feel the grout between the pieces. That is the test.
Why does a mosaic panel weigh more than a print?
Because it is glass, clay, mortar and a 12 mm birch panel. We do not print a weight on this page; what buyers tell us is that it is heavier than they expected, and that the weight is part of what makes it feel like mosaic rather than a picture of one.
The keyhole hanger on the back and a single screw carry it. The hanging guide says what to drive the screw into. If you want to feel the weight before you order, the markets are the place: the about page lists them.
Questions this leaves
Does the glass fade in sunlight?
No. Direct sun is fine; it is glass and clay. The colour in smalti is in the glass itself, melted in with the metal oxides, and the colour in the ceramic is a fired glaze. Neither sits on the surface where light could take it off.
Is the ceramic glazed or painted?
Glazed and fired, by a potter two streets away from the studio. The colour is the glaze, fused onto the clay in the kiln, so it is as permanent as the glass beside it. Nothing on the panel is painted on afterwards, and nothing on it is a print.
Can I see the materials before I order?
Yes, at the markets: the Railyard Artisan Market in Santa Fe on Sundays, the Blue Genie Art Bazaar in Austin every winter, and Brooklyn Flea a few weekends a year. Photographs never get the light right, which is why we pack the range into the van and take it out.
Is the panel sealed?
The birch is sealed before the mortar goes on, so the panel will not warp, and the finished surface is waxed as the last step after the grout is cleaned off. The care that follows is one line: dust with a dry cloth, and never soak the grout.
