Texas talc (left) and Montana talc (right)
Texas talc contains some amorphous carbon. The carbon is not stand-alone, but as CO2 in the dolomitic part of the ore. It produces 7% LOI
Context: Amtalc-C98, Pioneer 2661 Talc, Silverline 303 Talc, Talc
Tuesday 14th August 2018
Stunning black silky matte glaze at cone 6
This contains 6% Mason 6666 gunmetal black stain. The base recipe, G2934, is an excellent balanced-chemistry host for a wide range of stains to produce equally stunning reds, yellows, oranges, etc. The fritted version of the recipe, G2934Y, provides an even better host. This glaze is affected by the ... more
Context: G2934Y - Cone 6 Magnesia Matte Low LOI Version, G2934 - Matte Glaze Base for Cone 6
Monday 13th August 2018
Tuning the degree of gloss on a matte black glaze
These 10 gram balls were fired and melted down onto a tile. The one the left is the original G2934 Plainsman Cone 6 MgO matte with 6% Mason 6666 black stain. On the right the adjustment has a 20% glossy glaze addition to make it a little less matte. Notice the increased flow (the ball has flattened ... more
Context: Matte Glaze, Cutlery Marking, Triaxial Glaze Blending
Sunday 12th August 2018
DO NOT leave outsides of functional ware unglazed
This mug is made from the strongest porcelain I have, it is so vitreous that the bare fired surface does not even coffee-stain. So I glazed it only on the inside. That created a time-bomb waiting for hot coffee! Three others did exactly the same. Four other mugs glazed on the outside were fine. Why? ... more
Context: Glaze Compression
Monday 6th August 2018
One gram of processed hectorite has a surface area of 750 square meters!
A combination of surface area, surface topography, surface chemistry
and surface electrolytics determines how plastic a clay is. This material is super plastic.
Context: Surface Area
Monday 6th August 2018
Mother Nature's Porcelain - From a Cretaceous Dust Storm!
Plainsman Clays did 6 weeks of mining in June-July 2018 in Ravenscrag, Saskatchewan. We extracted marine sediment layers of the late Cretaceous period. The center portion of the B layer is so fine that it must have wind-transported (impossibly smooth, like a body that is pure terrasig)! The feldspar ... more
Context: B Clay, Clay and dinosaur country in southern Saskatchewan, Vitrification
Monday 6th August 2018
Pinholing at a cone 6 stoneware mug. Why?
It was put into the kiln before it was dry (from glazing). The kiln was fired fairly fast (without using a drop-and-hold firing schedule). These glazes have significant boron, they melt early and seal the surface. But water vapor can remain until surprisingly high temperatures. And it needs to get ... more
Context: Pinholing, Firing Schedule, Glaze Blisters
Monday 30th July 2018
Outside tenmoku glaze meets inside transparent in a straight line at the rim
An example of how a liner glaze can meet another at the rim of a piece. This it quite simple to do. The technique is especially practical where mug walls are thin and cannot absorb enough water to dry the glaze after immerse-dipping. It is essential where the outer glaze is potentially leachable, or ... more
Context: How to Liner-Glaze a Mug, Liner Glaze
Monday 23rd July 2018
Layering glazes to get variegation
Example of the variegation produced by layering a white glaze of stiffer melt (a matte) over a darker glaze of more fluid melt (a glossy). This was fired at cone 6. The body is a stoneware and the glazes employ calcium carbonate to encourage bubbling during melting, each bubble reveals the color and ... more
Context: Reactive Glazes, Glaze Layering
Monday 23rd July 2018
An additive that will make a glaze crawl
Light magnesium carbonate has been added to a low temperature terra cotta
white glaze (about 10%). It induces crawling
. It also mattes the glaze because it sources MgO. “Snakeskin” recipes to produce this effect can call for much higher percentages, but of course, fired properties (like color, gloss, thermal expansion
) will be much more affected.
Context: Light Magnesium Carbonate, Crawling
Thursday 19th July 2018
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