brian
New Member
Posts: 5
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Post by brian on Jul 25, 2018 15:42:03 GMT -6
Hello, I have a new glaze I am testing. It is not a crystalline glaze, but where it is thicker, as it starts to dry it can crack and start to peel off. The glaze contains a high amount of redart clay. Is there anything I can add to the glaze to keep if from cracking without changing how the glaze comes out too much? Thanks.
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paul
Junior Member
Posts: 51
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Post by paul on Jul 25, 2018 20:09:06 GMT -6
I have seen that when there is too much water mixed in it.
Try washing it off, let the piece dry. Then start over.
Then let the glaze settle and scoop some of the water out, it could take a couple days to settle enough.
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Post by tileman2 on Jul 25, 2018 20:27:26 GMT -6
Hi Brian:
When minerals constitute a glaze ( feldspars, silica, dolomite, spodumene, etc.) a suspender is used. Bentonite for example.
When glazes contain high % of clay: then the rules change slightly: and a plasticizer is used. In this case, CMC gum at 1-2% would be useful. Red bodied clays are high iron clays and by nature are prone to rapid dehydration. This problem is compounded further when applied to bisq that wicks water. It would also help to bisq to cone.4, which is less absorbent.
Tom
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gczop
Full Member
Posts: 202
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Post by gczop on Jul 28, 2018 18:11:08 GMT -6
Brian,
I'm using redart with adds of whiting and magnesite for an Albany slip substitute.
Tom is spot on, start with 2% CMC.
Calcining redart to say 500c simplifies matters.
Water: try a puddinglike consistency say 50 g water /100g dry glaze, add to suit.
Good luck, Gordon
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