Oxide and carbonate washes: the oldest trick in the glaze room.

The oxide cast, one metal at a time

Each metal has a personality, and each one behaves differently depending on the kiln’s atmosphere, oxygen-rich oxidation versus oxygen-starved reduction. Each entry says what happens in oxidation and in reduction where it matters; the atmosphere section below explains which one applies here.

1. Red iron oxide, the workhorse. In oxidation: honey, amber, rust, and toasted brown, warm and forgiving, gorgeous wiped back over texture. In reduction it turns moody, feeding celadon greens and tenmoku blacks. Cheap, forgiving, and the first oxide wash to try.
2. Black iron and yellow ochre, the cousins. Coarser or earthier iron sources that read softer and speckle more; treat them as seasoning variations on the workhorse.
3. Copper carbonate, the chameleon. Oxidation: greens from spring leaf to blackened bronze depending on strength and the glaze above. Reduction: the famous blood reds and flashed pinks. Strong and a little runny-tempered under fluid glazes.
4. Cobalt carbonate, the tyrant. Blue in nearly any atmosphere and shockingly powerful: a wash that looks like weak tea fires like midnight. Always the smallest recipe, always tested first, magnificent as inky brushwork.
5. Manganese dioxide, the bronze-maker. Browns, plums, and metallic bronze effects, especially where it pools. Manganese carries the strongest warnings, so be strictest with it, but every dry oxide and carbonate here needs a fitted respirator (an N95 at the least) on before the jar opens, plus gloves, wet cleanup and never a broom. Keep manganese-heavy work modest, wash your hands before you touch your face or your lunch, and talk to the studio team before you mix, because anything you bring in has to be cleared before it goes into a kiln.
6. Rutile, the weathermaker. Titanium-and-iron ore that gives tans, creams, and mottled variegation, and famously stirs up any glaze laid over it. Less a color than a special effect.
7. Chrome oxide, the stubborn green. Opaque, forceful, refuses to budge in any atmosphere, and famous for one party trick: near tin-white glazes it can turn another member’s pot pink in a shared kiln. Use sparingly and tell us at drop-off.
8. Nickel oxide, the mutterer. Muted grays, browns, and olive tones that never shout; the cast member you reach for when everything else feels too loud.

Application: where washes earn their keep

1. The wipe-back is the signature move. Brush wash generously over textured bisque, let it lose its shine, then sweep the high surfaces clean with a barely damp sponge. Color stays trapped in every stamp, carve, and tool mark, and suddenly your texture has a hundred percent more opinion. Pairs perfectly with everything on our texture imprinting page.
2. Brushwork reads like ink. Thin washes behave like watercolor: strokes, splatters, and calligraphy that keep their gesture in the fire. Cobalt ink on pale clay is the whole history of blue-and-white pottery in one move.
3. Under glaze or over glaze, different arguments. Wash under a transparent glaze stays crisp and sealed in; wash brushed over an unfired glaze melts into it, softening, haloing, and sometimes running. Both are legitimate; test both; label which was which.
4. Bare wash is an outside-only finish. Unglazed wash on fired clay is beautiful, dry, and slightly raw, right for sculpture and the outsides of planters, wrong for anything that touches food. Keep bare washes off eating surfaces. Under a fitted clear glaze a wash can go inside too, but the glaze is what makes the surface safe, so check it in the Food Safe Lookup. The full logic lives on our food-safe claims page.
5. Strength is a dial, not a setting. Every wash can be brushed weak like tea or built strong like espresso, and the same jar does both. When in doubt, apply thin and add a second pass; a too-strong metallic crust is much harder to walk back.