Print

G2934 Cone 6 MgO Matte Base

Description

For Stonewares and Porcelains.

A dolomite silky matte for cone 6. It fires translucent rather than completely transparent (because it is a matte). If you want pure white, add Zircopax (start with 5%, but keep it at a minimum to minimize cutlery marking).


G2934 Cone 6 Matte base (upper left sample) with various stain additions. A porcelain body has been used.

Firing

The degree-of-matteness is very dependent on cooling rate. Fast cooling (e.g. free-fall in a lightly-loaded or smaller kiln) produces our desired silky matte surface. Slow cooling (e.g. a heavily loaded kiln) produces a more matte and drier surface (subject to cutlery marking). Do test firings to determine if you can adapt your firing to this recipe or need to adapt this recipe to your firing. If the latter, blend in some glossy G2926B to shine it up to the degree needed.

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 the drop-and-hold PLC6DS firing schedule. 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.

G2934 matte is an excellent color base and works particularly well with inclusion stains. However, each different color created will likely require fine-tuning the degree of matteness. It is already quite matte, to shine it up slightly by blending in some of our clear glossy base glaze G2926B (click here to see an example).


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).


G2934 + 5% Titanium thinner/thicker on M390 at cone 6

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 technical information and more pictures check the G2934 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.

Mixing Instructions

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 G2934 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 1.43-1.44 and gelling the slurry to make it thixotropic (see next paragraph). Water weight: Powder weight x 0.9. Yield is about 1.4 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.

Gallery


12% yellow and 8% orange stains in G2934 base recipe. The silky surface of these is outstanding! It depends on the PLC6DS firing schedule.


G2934 with yellow stain (left) vs. a glossy glaze (G2931K with the same yellow stain but fired at cone 03). The matte surface is much easier on the eyes for bright colors (and much more pleasant to the touch).


Right pail: 2 gallons of G2934 base with 10% Cerdec yellow stain. Cost: $135. Jars with the same amount: Almost $300! And you have to paint them on in three coats with drying in between. The one in the pail is a true dipping glaze. You can dip a bisque mug for 2 seconds and it dries immediately in a perfectly even layer (if mixed according to our instructions).


G2934 Black with Amaco PC-32 brushed over it. Fired at cone 6 on buff stoneware. PLC6DS firing schedule.


Handmade mugs by Tony Hansen. G2934Y glaze with stains on P300 and Polar Ice. PLC6DS firing schedule.

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