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| Monthly Tech-Tip | No tracking! No ads! No paywall! |
I need to control the particle size of this product. I have already smashed it up (using a flat pestle hammer, my “Shusher”) and am now sizing it. That involves getting what I can through the screen and then going at the larger sized particles with the pestle again. This has to be done carefully, or too many fine particles are generated. I use three screen sizes in this procedure so that I can control the distribution of particle sizes in the fired product (to more closely match reduction fired ware). This method is also good for making your own grog, using this multi screen technique you could also control the distribution of sizes.
This can be a dusty procedure and those particles are angular and sharp and high in heavy metal, so it is best to do this outside in a breeze or with a ventilator and mask.

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This inch-thick iron plate welded to a five-foot-long heavy pipe produces an ideal “mortar and pestle” style tool to break down dry clay lumps on a cement floor. I sometimes add side rails to contain flying lumps, but when crushing softer materials, like the clay shown here, they are not needed. On a heavy iron plate (instead of the floor), I can crush rocks and bricks. By incorporating appropriate sieves, I can effectively create granular material down to 50 mesh or finer.
I discovered the utility of this during the time the movie “Home” was popular, so I dubbed it “The Shusher” after Captain Smec’s control staff (more precisely the rock on the end of it).

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I mixed a cone 6 porcelain body and a cone 6 clear glaze 50:50 and added 10% Mason 6666 black stain. The material was plastic enough to slurry, dewater and wedge like a clay, dry and break into small pieces. I then melted them at cone 6 in a Zircopax crucible (I make these by mixing alumina or zircopax with 3-4% veegum and throwing them on the wheel). This material does not completely melt so it is easy to break the crucible away (it does not stick to the zircon). I then break the black up with a special flat metal crusher we made, size them on sieves and add them to glazes for artificial speckle. If specks fuse too much I can lower percentage of glaze (and vice versa). Of course, the particles are glass, jagged and sharp-edged so care is needed in handling them.
| Glossary |
Reduction Speckle
A sought-after visual effect that occurs in reduction fired stoneware. Particles of iron pyrite that occur naturally in the clay melt and blossom up through the glaze |
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