G2934 cone 6 DIY matte glaze: Reliable, durable, adjustable, stainable

These pieces were made from Plainsman Polar Ice and fired to cone 6 using variations on the PLC6DS and C6DHSC schedules. The dipping glaze is G2934Y, a recipe variant of G2934 having a finer micro-surface texture (it has the same chemistry but the MgO is sourced from a frit and talc instead of dolomite). These mugs display varying degrees of matteness depending on the cooling rate of their firings and the percentage of glossy G2926B base we blend in. As an MgO matte, this glaze is can have a surface very pleasant to the touch. It fires durable, can be quite matte without cutlery marking and it has very good slurry and application properties (as a dipping glaze). It has a very low thermal expansion (won’t craze). It works really well with stains (except purples). It melts even better than the glossy!

Related Pictures

Souvenir mugs that demonstrate incredible workmanship, glaze recipes, use of decals

These porcelain mugs are sold at many tourist shops on the Alaskan cruize circuit. Made in China of course. But their quality is astounding. And they teach multiple lessons to potters - great skill in the use of decals (even inside), meeting different glazes at the rims, evenness of application, layering, the use of wax resist, etc. They likely have a glossy and matte base glaze and add stains (to get the black, blue, red, white, green). Notice they have an iron red (lower right) that is stable enough not to run and host an even more fluid melt second layer. They also have a stoney yet functional matte white (bottom left). You can make dipping glaze versions of all of these:
Black glossy: G3914A and G2926BL
Black matte: G2934BL
Iron Red: G3948A
White stoney matte: G2934Y2
Glossy colors: Add stains to G2926B
Matte colors: Add stains to G2934

G2926B cone 6 transparent liner glaze: Proven, reliable, durable

A hand made pottery mug with clear liner glaze

While colorful and layered glazes on the outsides of pieces get lots of praise and glory transparent or white glazes providing the functional surface on the insides of pieces often get little attention from potters. Really, what good is an attractive piece if the food surface is crazing, blistering, leaching or cutlery marking? Or if it converts the piece into a time bomb? This cone 6 liner glaze, G2926B, is an example of how I found a glaze, recognized its potential and then adjusted the recipe to resist crazing on our clay bodies, fire durable and leach resistant act as a base to host colorants, opacifiers and variegators. I get the best fired results using the C6DHSC firing schedule and very good performance as a dipping glaze when the slurry is thixotropic. One of the reasons this recipe is so widely used is that it is well-documented having a code number that Google indexes. Drinking from a mug having a quality and fitted functional surface and a nice crisp line dividing the outside and inside glazes instills pride in me as the maker. What is the outside glaze? It is the G2934Y matte base recipe plus 8% Mason 6027 stain. The clay is MNP which I make myself.

Mason stains in the G2934 matte base glaze at cone 6

Stains can work surprisingly well in matte base glazes like G2934. But they perform differently in a matte host glaze. The glass is less transparent and so varying thicknesses do not produce as much variation in tint. Notice how low many of the stain percentages are here, yet most of the colors are still bright. A good reason to minimize stain concentration is to avoid leaching. We tested 6600, 6350, 6300, 6021 and 6404 overnight in lemon juice, they passed without any visible changes. It is known that MgO mattes, like this one, are less prone to acid attack that CaO mattes. A down-side to the MgO-matte-mechanism is that chrome-tin stains do not work (e.g. 6006), high CaO content is needed in the host glaze to develop the color. The inclusion stains 6021 and 6027 work very well in this base. As do the 6450 yellow and 6364 blue. And the 6600 produces an incredible gunmetal black. The 6385 is an error, it should be purple (that being said, do not use it, it is ugly in this base). The degree-of-matteness can be tuned by blending in some G2926B glossy base.

Links

Recipes	G2934 - Matte Glaze Base for Cone 6 A base MgO matte glaze recipe fires to a hard utilitarian surface and has very good working properties. Blend in the glossy if it is too matte.
Recipes	G2934Y - Cone 6 Magnesia Matte Low LOI Version The same chemistry as the widely used G2934 but the MgO is sourced from a frit and talc instead of dolomite. It has a finer surface, less cutlery marking and staining.

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