Zero3 K Transparent Glaze


This glaze was originally designed to work with the Zero3 engobe, stoneware and porcelain (fired at cone 03). It also works well on L212, L215. It is exceptionally glossy and transparent (when fired according to our instructions) and it is durable and fits very well. No common middle or high temperature glaze can compare if you are doing underglaze decoration, the brightness and clarity of color are stunning!

Process Properties

Screening: We have not ball milled this product, thus it may contain some oversize particles from the constituent materials. We advise sieving the glaze slurry to at least 80 mesh.


To get the best defect-free surface please consider using a hold-rise-drop-hold firing schedule (you can find more information about it on this page).


This glaze is more sensitive to thickness than most stoneware glazes. If too thin it will not be smooth, if too thick it will run during firing. Be sure that ware has been fired to the temperature for optimal porosity for glazing. If bisqued too high ware will not be absorbent enough for the glaze to stick in a sufficiently thick layer. Conversely, if ware is bisque fired too low or ware is immersed too long during dipping, the glaze will go on too thick and run during firing. If you are brushing consider just two layers. Whatever you do, we recommend a test firing to verify. Keep good records of your bisque temperature and maintain the glaze at the right specific gravity and viscosity.


As of June 2017 it is not yet available as a premixed product. But you can mix to yourself. For our lab information on the recipe, how to mix and use it click here.

Zero3 Clear glaze with stains for primary colors, brown and black. These are 10 gram balls that have been melted down onto a tile (they thus show it very thick). The tiny bubbles are not present on glazed ware (especially if 2-3% zircon is added).

Primary color stains in G2931K

In the above images, the stains have been mixed right into the clear glaze powder to get the six primary colors. Using these primary colors you can blend almost all color you want. Lighten any color by diluting with the clear.


Zero3 Porcelain mug fired at cone 03 in 3 hours. Notice how ultra-clear the Zero3 K glaze is over the underglazed areas. No micro-bubbles. It is applied in a very thin layer. By Tony Hansen.

Zero3 Stoneware mugs decorated with underglazes and finished with G2931K ultra clear glaze. By Tony Hansen.

Buffstone and L215 with underglaze decoration and G2931 clear glazes. But they are not the same. The G2931L glaze (left) has a lower thermal expansion (to prevent crazing on Buffstone). The G2931K glaze fits L215 because the latter contains some talc (which raises its expansion). Both of these mugs have survived a 300F-to-ice-water thermal shock without crazing or shivering. If you switch the glazes the Buffstone mug would craze it and the L215 would shiver it off in flakes.

L212 underglaze decorated mug fired at cone 03. Outside glaze is G2931H clear. Inside is Crysanthos SG001 white.

Zero3 Porcelain, Zero3 base glaze with 10% inclusion stains and 2% zircopax added. Insides are Zero3 K transparent.

Buffstone, L212 and L213. Each has its own clear glaze. G2931L, K and H. L is low expansion (for zero talc porous bodies). K is intermediate (for moderate talc bodies like L215 and Zero3 stoneware and porcelain). H is high expansion (for high talc bodies like L212, L213).

Safety Data Sheet

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702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508