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LydiaJ

Copper Sulphate & Crazing?

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LydiaJ    0

I received a beautiful green that came out of a line blend of 28 tiles. It was a vibrant, rich, and glossy color- but it had severe crazing (picture attached). Its colorants were copper sulfate and rutile. Interestingly enough, only the tiles in the line blend that contained copper sulphate had crazing.

 

I tried to “fix†the problem by increasing/decreasing the silica by increments of two, eight times, only to see no change whatsoever.

 

The information from both of the paragraph above have led me to conclude that copper sulphate is the culprit! But I am no glaze expert- maybe I am missing the mark.

 

Does copper sulphate encourage/increase crazing? Is this problem worth solving? Any thoughts/insight/experiences would be greatly appreciated!

 

Neph. Syen 67

Whiting 15

Flint 15

Bent 3

 

copper sulphate 5%

rutile 5%

 

 

post-2052-12796821195309_thumb.jpg

 

 

 

Warm Regards,

 

Lydia

post-2052-12796821195309_thumb.jpg

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Matt Katz    11

Most likely not.

 

Crazing is a result of a fit mismatch between the glaze and the body. They formula presented has no clay, which introduces Alumina.

Your instinct to increase flint was partially correct, but only adding in Flint and not Clay will not always fix the problem.

 

I received a beautiful green that came out of a line blend of 28 tiles. It was a vibrant, rich, and glossy color- but it had severe crazing (picture attached). Its colorants were copper sulfate and rutile. Interestingly enough, only the tiles in the line blend that contained copper sulphate had crazing.

 

I tried to “fix†the problem by increasing/decreasing the silica by increments of two, eight times, only to see no change whatsoever.

 

The information from both of the paragraph above have led me to conclude that copper sulphate is the culprit! But I am no glaze expert- maybe I am missing the mark.

 

Does copper sulphate encourage/increase crazing? Is this problem worth solving? Any thoughts/insight/experiences would be greatly appreciated!

 

Neph. Syen 67

Whiting 15

Flint 15

Bent 3

 

copper sulphate 5%

rutile 5%

 

 

post-2052-12796821195309_thumb.jpg

 

 

 

Warm Regards,

 

Lydia

 

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LydiaJ    0

Thanks Matt. The Nepheline syenite supplies alumina, but I think you are right in that I need to add feldspar/kaolin. I was trying to get the glaze to fit without altering the original recipe...Its likely I won't end up with the same glossy, vibrant green. But I guess that's the intrigue of ceramics! Thanks for the input.

 

 

 

 

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