Glaze material · Fluxes, feldspars & frits
Wollastonite
Also sold as: Vansil
Calcium silicate — a source of calcium flux and silica together, without the carbonate gas of whiting.
In published recipes
Used in 1,298 of 10,859 glaze recipes (12%)
Typical amount when present
15% of the dry batch — half of recipes fall between 8.1% and 22%.
Fired surface of those recipes
Glossy 70% · Semi-glossy 14% · Satin matte 9% · Satin 7%
Most often mixed with
Materials that appear in the same recipes most often.
Chemistry
- Raw formula
- CaO·SiO2
- Molecular weight
- 116
- Fired formula
- same as raw
- Equivalent weight
- 116
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
Can replace whiting and flint in a recipe; because it releases no CO₂, it is a common fix for pinholing and boiling problems.
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 Wollastonite do potters use in a glaze?
- Across 1,298 published glaze recipes containing it, the typical amount is 15% of the dry batch, with half of recipes between 8.1% and 22%. 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 Wollastonite used at?
- It appears in recipes across the range; the most common cones among published recipes are cone 6, cone 10, cone 5. Where a material sits depends on the rest of the recipe more than on the material itself.
- Is Wollastonite 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.
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.
Claybench tracks your glaze materials, not just recipes
Inventory, hazard flags, and per-piece material cost — the same reference behind this page, wired into your studio.