Transparent Cone 6 Whiteware Glaze
For Whitewares, Porcelains. Plainsman code G2926B.
Intended for use on M370. It has the lower thermal expansion necessary to fit (without crazing). It sources boron from a frit instead of troublesome Gerstley Borate (you need to see and use this side-by-side with a Gerstley Borate based glaze to appreciate how much better this is). This recipe has good suspension and very good application properties, IF it is the correct consistency.
G2926B Whiteware transparent with various stain additions on a porcelain body. It does not work as well as the G2916F Transparent for chrome-tin stains.
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 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. The percentages of stain shown are suggestions. For some colors you may need to use more, others less (your fired results will demonstrate if the glaze is too dark or too light for your liking). If you are glazing a dark-burning body, consider applying a white engobe to areas where you want bright colors. For functional surfaces that you want to be white, consider applying a white engobe to the inside of the ware (at the leather hard stage) and using a transparent, this will give a much cleaner and more homogeneous surface than (white glazes do not cover well over a dark bodyies). If you are new to the use of engobes and fire cone 6, consider starting with this one.
Still getting crazing, perhaps on P300? Check G3838A.
We recommend a specific gravity of 1.44 (to get that multiply the total weight of powder by 1.04 to determine the amount of water). To prepare it for use, add the powder to 90% of the water and mix until it flows well. Then adjust the amount of water to get the right specific gravity (more water to lower it). If needed, adjust the viscosity to prepare for sieving through 80 mesh. If the slurry is thin, there is a danger of it settling out while sieving, so it must be gelled. To do that add enough flocculant (vinegar, epsom salts) so that the slurry mass stops motion in about 5 seconds after mixing or stirring is ceased. Flocculants are powerful, only a few drops of vinegar (or pinches of crushed epsom salts) per gallon are needed.
After sieving do a final viscosity adjustment to make the slurry thixotropic (thixotropic liquids gel after motion stops). You can "see" the slurry thixotropy by noting a "bounce-back" on final stop-motion after stirring. Add enough flocculant to get stop-motion in around 2 seconds (in a 1-2 gallon bucket). As before, be careful in adding the flocculant, it is easy to add too much and get a bucket of jelly (if that happens add (by the drop) Darvan to re-thin it). When the slurry is right, you can two-second-dip a piece and on withdrawl it will drain well, gel quickly, only a few drips will fall and on turn-over the glaze will not run back down. It will apply in an even layer on dense or porous bisque. This "rheological state" of the glaze slurry can change on storage so be ready to adjust it later. Recheck the specific gravity from time to time and, if needed, adjust by adding or removing water.
As you gain confidence with doing this you will be able to create a thixotropic slurry at a range of specific gravities. Our recommended specific gravity is based on how much water is needed to get the undeflocculated glaze to a state where it needs about 2 grams of epsom salts per gallon to gel.
Underglazes with M370 and G2926B transparent. The colors were airbrushed and the clear glaze was sprayed over top.
Safety Data SheetClick here for web view.
|Plainsman Clays Ltd.|
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508