Jump to content


Member Since 06 Feb 2012
Offline Last Active Mar 25 2016 08:16 PM

Topics I've Started

Glaze Cracking On Bisque

08 October 2013 - 08:26 PM

I'm having an issue with one of my glazes cracking as it dries on the bisque. The problem is worse when it is put over another glaze. This of course leads to crawling on the fired ware. I've tried using Veegum T to toughen it up, but not to much effect. I have just inherited some CMC, but I don't know how to use it. Is that a possible solution to this problem? Or do I need to do something else?




23 September 2013 - 09:25 PM

Since this came up in another thread...

How does COE work in a relative sense? I understand the dilatometer sense. But the COE of one glaze relative to one body doesn't seem to have the same effect as the COE of another glaze on the same body, at least as far as failure goes. Am I correct?

I've been looking at glazes that are within Insight or in the Roy/Hessleberth book and I find what seems to me to be a pretty wide range of COEs. I've been assuming that a COE of ~7.8 (Insight) to be the upper limit, and ~6.5 to be the lower limit. Is this even close to right?



Cone 6 Black

16 September 2013 - 01:28 AM

Anyone have a ^6 black recipe that is reliable in that kiln-to-kiln way? I've tried a couple off the net, including one that had Ron Roy's name on it, and they were less than acceptable.

Would anyone care to share a nice glossy black in trade for my humble appreciation?



Glaze Chem Question

12 September 2013 - 11:11 PM

When using my glaze calc. software I've noticed that I can raise my Al/Si without it affecting my RO numbers in the unity formula. Granting that I will ultimately go out of my limits, outside of those limits is there a rule of thumb about the relationship of fluxes to non-fluxes?



Free Silica

26 August 2013 - 10:52 PM

Please excuse me if I've asked this before, but, can anyone give me a good definition of 'free silica'?


I'm thinking that it is silica in a clay body that isn't a part of the Al2SiO2H2O molecule. Is that right?