Shino looks like a beginner's glaze — white, matte, a bit rough — and it is one of the hardest glazes to make well, because almost everything that defines it happens during the firing rather than in the bucket. The recipe is simple and the process is not: it needs to be applied thick, fired in heavy reduction early, and cooled in a way that traps carbon against the body.
H 16 · Ø13 / Ø15 / Ø7 cm
Base
A traditional American shino: high feldspar, high clay, very little silica, and enough soda ash to make the surface foam. Applied thick and fired in reduction, it produces the orange-peel white with carbon-trapped orange patches that defines the family.
| Material | Parts | Share |
|---|---|---|
| Custer Feldspar | 55 | 54.7% |
| EPK Kaolin | 25 | 24.9% |
| Nepheline Syenite | 15 | 14.9% |
| Soda Ash (Na₂CO₃) | 2 | 2.0% |
| Bentonite | 2 | 2.0% |
| Red Iron Oxide (Fe₂O₃) | 1.5 | 1.5% |
| Total charge | 100.5 |
Fired surface
A thick, semi-matte white with an orange-peel texture and orange to rust patches where the carbon from the reduction was trapped under the glaze. Where the glaze breaks on a rim, the iron shows as a warm brown line.
Why the recipe is mostly feldspar
At 55 percent feldspar and 25 percent kaolin with no added silica, this glaze is barely a glaze at all in the conventional sense: it is a feldspar slip that melts just enough to bond to the pot. That is deliberate. The high feldspar content gives the surface its characteristic crazed, slightly crystalline look, and the 25 percent kaolin keeps a thick application from running off the pot in the kiln.
There is no silica in this recipe. Adding even 5 percent will give a smoother, glossier surface and lose the orange-peel texture that makes a shino recognisable. If you want a smooth white, use a different recipe.
Soda ash and the mixing problem
Soda ash is soluble. If you mix this glaze and leave it standing, the soda ash dissolves into the water, migrates to the top of the bucket and produces a surface that foams and pinhols. There are two fixes: mix only what you will use within a week, or substitute 1 percent sodium silicate for the soda ash, which is less soluble but changes the foaming slightly.
Because soda ash is soluble, this glaze also needs to be sieved and used the same day if possible. A bucket that has stood for a month can be stirred back into use, but the first few pots dipped will behave differently from the last.
Thick application and heavy early reduction
Apply shino at 1.2 to 1.5 mm — noticeably thicker than any other glaze in this library. A thin shino is a flat, dry, uninteresting white; the texture and the orange patches only appear when there is enough material on the pot. Dip twice with a fifteen-minute dry between dips.
Fire in heavy reduction from 900 degrees and hold it through 1200. The carbon that the flame deposits on the glaze surface is what produces the orange-to-rust patches, and it only sticks if the glaze is present and the atmosphere is genuinely smoky. A clean, well-adjusted reduction gives a plain white shino with no character at all.
Cooling, and the carbon trap
The orange patches on a good shino form partly on the way down. Cool the kiln slowly from cone 10 to about 900 degrees over four to six hours rather than letting it drop freely; the carbon that was trapped in the glaze during reduction migrates and concentrates in the thicker areas during the slow cool, which is what produces the blotchy patchwork rather than a uniform tint.
If your kiln has no cooling control, a common substitute is to fire slightly heavy in reduction and damper the kiln down at the end of the firing to slow the first part of the cool. It is less controllable but it does produce patches.
Steps
- Weigh the feldspar, kaolin, nepheline syenite, iron oxide and bentonite and combine them dry.
- Dissolve the soda ash in a small amount of the mixing water, then add the dry materials.
- Mix for six minutes, then adjust to 1.45 specific gravity and sieve through 80 mesh.
- Use the glaze within a week, or substitute 1 percent sodium silicate if it must stand longer.
- Apply at 1.2 to 1.5 mm by dipping twice with fifteen minutes of drying between dips.
- Load with at least 2 cm between pieces; shino foams and will touch its neighbours.
- Fire with heavy reduction from 900 to 1200 degrees, then medium reduction to cone 10.
- Cool slowly from cone 10 to 900 degrees over four to six hours by damping the flue.
- Examine the patches after the kiln reaches room temperature; do not open hot.
Where it goes wrong
- Mixing a large batch and leaving it for months. The soluble soda ash migrates and the glaze foams.
- Applying thin, under 1 mm. The result is a flat dead white with no texture.
- Firing in clean reduction. No carbon means no orange patches, just a plain white.
- Adding silica to smooth the surface. It works, and it stops being shino.
- Loading pieces close together. Shino foams and will fuse to its neighbours.
| Symptom | Cause |
|---|---|
| Surface is a plain uniform white with no orange patches | reduction too light, or the glaze applied too thin. |
| Heavy pinholing and a bubbled surface | soda ash migrated in an old bucket; mix fresh or switch to sodium silicate. |
| Glaze crawled or peeled away from the body in patches | application above 1.6 mm on a dusty or greasy bisque. |
| Pieces fused to each other in the firing | shino foams and needs at least 2 cm of clearance. |
Recipe and schedule numbers here were recorded on the workshop’s own kiln. A different kiln, a different thermocouple position or a different clay batch will move the result, so treat every firing schedule as a starting point and keep your own log beside it.