Print

G2916F Transparent Cone 6 Stoneware Glaze

Description

For Stonewares like M340, M325, M390, M350.

This is an industrial tableware glaze recommended by tech support at Fusion Frits. It not only fires hard and crystal clear but has outstanding suspension and application properties. In addition, it works well with most stains.

The magic for the way this glaze fires and its hardness and durability lie in the variety of fluxes in contains and the very low boron content coupled with high SiO2 and Al2O3. The fluxes most likely to create micro-bubbles at this temperature are sourced in a frit. It has the traditional CaO and KNaO, but the talc adds MgO and the frit adds SrO plus a tiny bit of BaO. This mixed-oxide effect produces a very well melting glaze yet having excellent body (considering it has only 18% of a low-boron frit).


G2916F stoneware clear glaze sample board with added Mason stains. Sample are porcelain.


Button melted samples of various stains in cone 6 stoneware clear glaze.

Firing

It is standard practice to fire cone 6 using a hold (or soak) at top temperature schedule (e.g. for 30 minutes) to produce a defect-free glaze. However we recommend a drop-and-hold firing schedule (like PLC6DS). Both require manual programming of your kiln (because none of the built-in programs do any kind of hold). If you have not manually programmed your kiln, this is a barrier you need to cross to produce more defect-free glaze surfaces.

Recipe

The recipe of this glaze is not proprietary. We developed it and sell it premixed but you can batch it (or even adjust it) yourself. For detailed technical information check its page, G2916F, at the Digitalfire Reference Library.

Adding the Stains and Opacifiers: Simply multiply the weight of the amount of powder you want to use and divide by 100. For example, if you have 2000 grams of glaze powder and want to add 6% stain: 2000*6/100=120 grams of stain. Or, 10% zircopax: 2000*10/100=200 grams of zircopax (stain %'s are suggestions, for some colors you may need more, testing is needed). Bright colors and whites will be muted on dark-burning bodies.

For darker firing bodies like M390, we recommend using the GA6A base Alberta Slip glaze.

Mixing Instructions

If you just want to mix it the traditional way, start with equal weights of water:powder and mix well using a propeller mixer. Add more water until it is creamy, try it, adjust, etc. To learn more visit the G2916F page at the Digitalfire Reference Library.

If you want better application properties (as a one-coat dipping glaze) we recommend targeting a specific gravity of 1.5 and gelling the slurry to make it thixotropic (see next paragraph). Water amount: Total weight of powder x 1.05. Yield: 1.2 litres per kg of dry powder.

To prepare for use as a single layer dipping glaze, add the powder to 90% of the water and mix until it flows well. Then add water to get the right specific gravity. Sieve through 80 mesh.

For the best working properties we want the slurry to be thixotropic (our thixotropic glazes gel after motion stops, they "bounce-back" on final stop-motion after stirring, in 2-5 seconds). A flocculant is added to achieve this (e.g. start at 1g of epsom salts per 1000g glaze powder). Be careful when adding the flocculant, it is easy to add too much and get a bucket of jelly (if that happens re-thin it by adding, Darvan by-the-drop). When the slurry is right, you can two-second-dip a piece and on withdrawal it will drain well, only a few drips will fall and on turn-over it will not run back down. It will apply evenly on dense or porous bisque. This "rheological state" can change on storage so be ready to adjust it later. Also recheck the specific gravity from time to time and, if needed, adjust by adding or removing water.

This can also be mixed as a brushing glaze or a first-coat dipping glaze.

Safety Data Sheet

Click here for web view.

Logo Plainsman Clays Ltd.
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508
Email: plainsman@telus.net