The classic opacifier for soft, warm whites and majolica, and the tin in copper reds.
You must test before you use it, at any scale. Raw materials, mined or man-made, are not consistent. Color, strength, particle size and chemistry can change from one bag to the next and from one supplier to another, even when the name on the bag stays the same. Before you use this material in a glaze, slip or clay body of any size, mix a small test batch, fire it on your own clay in your own kiln, and check the results.
What it is
An opacifier: a white powder that turns a clear glaze into an opaque white. Tin white is softer and warmer than zircon white, and it's the traditional white of majolica pottery. Small amounts also help copper red glazes develop their color.
Getting started
- For an opaque white, start at 5% (5 grams per 100 grams of dry glaze). Most glazes are fully white by 7 to 10%.
- For copper reds, recipes usually use about 1%.
- Tin is expensive. For a lower-cost white, a zircon opacifier like Ultrox works, though the white is cooler and brighter.
- Keep tin glazes away from chrome. Even chrome in a nearby pot in the same kiln can turn a tin glaze pink.
For glaze formulators
- Tin oxide, SnO₂. Stays in the glaze as tiny undissolved particles that scatter light.
- Stronger per gram than zircon: zircon opacifiers typically need about 1.5 to 2 times as much for similar opacity.
- With chrome: pinks and reds (chrome-tin pink).
- Used in copper reds and lustre glazes.
Safety
- Low toxicity, but don't breathe the dust. Wear a NIOSH-approved respirator (N95 or better) when handling it dry, and clean up with a wet sponge, not a broom.
Sizes & pricing
| Size | Price | Per lb | |
|---|---|---|---|
| 1 lb | $58.10 | $58.10 | Add to cart |
| 5 lb | $276.50 | $55.30 | Add to cart |
| 10 lb | $525.50 | $52.55 | Add to cart |
| 25 lb | $1,245.00 | $49.80 | Add to cart |
| 55 lb bag | $2,281.50 | $41.48 | Add to cart |
Full bags mix and match. Every full bag in your order, of any raw material, adds up. That total sets the price of every bag. Smaller sizes don't count.
This bag's price stays the same at every level, but it still counts toward your full-bag total.
Prices from our October 23, 2026 price list.
Frequently Asked Questions
CUSTOMER REVIEWS - Q&A
Got a question about this product? Ask it here and get a response from our staff and also input from the Sheffield Pottery community!











