Glaze material · Colorants
Black iron oxide
Also sold as: ferrous oxide
Iron in its ferrous form — coarser than red iron oxide, otherwise the same colorant.
In published recipes
Used in 81 of 10,859 glaze recipes (0.8%)
Typical amount when present
2.8% of the dry batch — half of recipes fall between 1% and 6%.
Fired surface of those recipes
Glossy 59% · Semi-glossy 17% · Satin matte 13% · Satin 11%
Most often mixed with
Materials that appear in the same recipes most often.
Chemistry
- Raw formula
- FeO
- Fired formula
- FeO
- ferrous
From Linda Arbuckle's materials table. Mineral formulas are idealized; buy an analysis for the bag you have. Equivalent weight is the weight that supplies one molecule of the fired oxide — the number glaze calculation uses.
What potters should know
Melts at low-fire temperatures; behaves like red iron in the melt but disperses less evenly, so it can speckle.
Handling and safety
Dry ceramic materials generate respirable silica dust. Use a NIOSH-approved N95 or P100 respirator and adequate ventilation when mixing dry, and wet-clean surfaces.
This information is provided for planning purposes and is derived from publicly available sources including OSHA regulations, NIOSH guidance, and manufacturer safety data sheets. It does not constitute professional safety advice. Consult your material suppliers' SDS documents and applicable local regulations for authoritative safety guidance.
Questions
- How much Black iron oxide do potters use in a glaze?
- Across 81 published glaze recipes containing it, the typical amount is 2.8% of the dry batch, with half of recipes between 1% and 6%. Colorants and additives sit far lower than fluxes and glass formers; treat these as a range to test around, not a target.
- What cone is Black iron oxide used at?
- It appears in recipes across the range; the most common cones among published recipes are cone 10, cone 6, cone 9. Where a material sits depends on the rest of the recipe more than on the material itself.
- Is Black iron oxide safe to use?
- It carries no specific hazard flag beyond the general rule for all dry ceramic materials: avoid breathing the dust and read the supplier's SDS.
Related materials
| Glaze material | recipes | typical |
|---|---|---|
| Red iron oxide | 2,413 | 4% |
Sources. Usage figures are computed by Claybench over 10,859 glaze recipes compiled from publicly shared community recipe collections (snapshot 2026-02-27) — counts only; no recipe is reproduced, and the figures describe that collection, not every recipe in existence. Material roles and notes are paraphrased from Linda Arbuckle's Ceramic Materials handout unless noted. Hazard notes summarise supplier SDS guidance; read the SDS for the product you buy.
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