Jump to content


Photo

Copper Sulphate & Crazing?


  • Please log in to reply
2 replies to this topic

#1 LydiaJ

LydiaJ

    Newbie

  • Members
  • Pip
  • 2 posts

Posted 20 July 2010 - 10:08 PM

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%


Attached File  IMG_0004.jpg   357.96KB   17 downloads



Warm Regards,

Lydia

#2 Matt Katz

Matt Katz

    Member

  • Members
  • PipPipPip
  • 46 posts
  • LocationAlfred, New York

Posted 21 July 2010 - 06:36 AM

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%


Attached File  IMG_0004.jpg   357.96KB   17 downloads



Warm Regards,

Lydia



#3 LydiaJ

LydiaJ

    Newbie

  • Members
  • Pip
  • 2 posts

Posted 21 July 2010 - 04:15 PM

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.








0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users