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Wikipedia terms Knapping as “the shaping of flint, chert, obsidian, or other conchoidal fracturing stone through the process of lithic reduction to manufacture .. flat-faced stones.” In other words, it is the process of carefully breaking off pieces to create sharp edges and controlled surfaces.
Knapping is a thing. r/Knapping on Reddit has 12k followers. There are lots of YouTube videos, articles and books, websites and even commercial suppliers. Michael Slack has answered the question: Could Zero4 porcelain be knapped? The answer, as you can see, is: Nicely. This is not an arrowhead but a proof of concept biface. Michael was motivated after seeing the glassy internal structure of the fired material. He used 0.3% cobalt, thus the blue color. If you attempt this be advised of the importance of extremely vigorous mixing of the slurry to remove all agglomerates. Try various temperatures to find the most knappable material.

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These Zero3 fritware bars are fired at cone 06, 04, 03 and 02 oxidation (bottom to top). This body has very low TiO2 and Fe2O3 levels. But the secret is the 0.2% blue stain (Mason 6336) it contains. Notice that almost no color develops at the lowest temperature, cone 06. But, as soon as glass development begins, by cone 04, so does the color.
This strategy is typically only suitable if a high-energy mixer is available. As a potter, blender mixing is thus essential to break up the stain agglomerates, otherwise tiny blue specks will appear. That mixing also separates the Veegum particles to get higher plasticity. The stain used here is Mason 6336. But this one may not work for you, just do testing to find the right one, at the right percentage.
Michael Slack is at it again. He is using a modified Zero4 recipe for knapping: 3 parts Frit 3110, 2 parts Georgia kaolin and 1 part silica (by volume). Whatever the weight is, he adds 3% bentonite. This develops the required density and hardness by 1045C.
| URLs |
https://goknapping.com/
GoKnapping.com - Supplies and learning |
| URLs |
https://en.m.wikipedia.org/wiki/Knapping
Flint Knapping at Wikipedia |
| Glossary |
Zero4
The designation for a group recipes for body, glaze and engobe (by Tony Hansen), that potters can use to make low fire stoneware and fritware porcelain |
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