G2934 Cone 6 MgO Matte Base G2926B Cone 6 Transparent Whiteware Base GA6-A/B Alberta Slip Cone 6 Base GR6-A Ravenscrag Cone 6 Base L3954B Mid Temperature Engobe Zero3 K Cone 04-02 Transparent Glaze G1947U Transparent Base - Cone 10R G2571A MgO Matte Base - Cone 10R GR10-A Ravenscrag Slip as-a-glaze - Cone 10R L3954N/J Cone 10 Engobe Base
G2926B Cone 6 Transparent Whiteware Base
For Whitewares, Porcelains
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 mixed to the correct consistency).
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.
The body is Plainsman M390. These are commonly used base glazes. The top one is an MgO matte, the next is a calcium matte. They behave very differently to these additions. Notice also that thickly applied titanium dioxide is very different. Tin oxide fires whiter than zircon (e.g. Zircopax).
The recipe of this glaze is open-source. We developed it and sell it premixed but you can batch it (or even adjust it) yourself. For detailed technical information its page at the Digitalfire Reference Library by clicking the following: G2926B.
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.
The story of two transparent base glazes: The inside one is our standard recipe. It is durable, glossy, clear and fits most bodies. It can be colored with stains, opacified and variegated. But it does not produce the brilliant metallic green when copper oxide is added (like this one on the outside). For that we recommend base base having high melt fluidity (it melts more), G3806C.
If you just want to mix it the traditional way, start with about 85 water to 100 powder (by weight) and mix well using a propeller mixer. Add more water until it is creamy, try it, adjust, etc. To learn more visit the G2926B 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 1.44 and gelling the slurry to make it thixotropic (see next paragraph). Water weight: Same as powder weight. Yield is about 1.4 litres per kg of dry powder.
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.
L3954B white engobe on M340 and M390. The engobe has been applied to the inside and wrapped over the rim to midway down the outside. The clear glaze on the inside is G2926B Whiteware transparent. The outside glaze on the right is that same clear with 4% added iron oxide. The outside glaze on the left mug is GA6-A Alberta Slip clear using Ferro Frit 3195 as the flux.
These Coffee Clay mugs have been white L3954B engobed at leather hard stage on the insides (the center one partway down the outside). After bisque the left and right ones were white-glazed on the inside (using G2926B+10 Zircopax). The one on the right has GA6-A (Frit 3195 version) on the outside (the center mug inside and out). The GA6-A over the black clay produces a very deep, rich ultra-gloss surface. The mug on the left has Ravenscrag floating blue (GR6-E) on the outside (producing a very right color over the Coffee clay).
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|Plainsman Clays Ltd.|
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508