Gojodo Posted December 29, 2018 Report Share Posted December 29, 2018 I’m looking for a clear zinc free commercial glaze that fits with Highwaters Brownstone clay. I’ve used Amaco HF 9 and it crazes. Unfortunately we no longer have our own studio and working in a group setting and must use commercial glazes. Any suggestions would be appreciated. Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 29, 2018 Report Share Posted December 29, 2018 Just an observation Crazing is a result of a glaze fit issue. Folks usually use zinc free to reduce the likelihood of their underglaze or mason stains being bleached or lightened by the overglaze. There are many commercial mid fire cone 5/6 glazes available, unfortunately unless tested on your clay body with your application techniques there is no sure fire way to know if it will not craze. A thick application of glaze can exacerbate a fit issue. In general glazes craze when the glaze shrinks faster than the clay body and they shiver when the clay body shrinks faster than the glaze. Suggestion Short of someone with experience with your clay, testing until you find a compatible glaze is usually required to solve fit issues. Amaco has an HF10 that is not guaranteed zinc free, but again if you do not have underglaze color issues then maybe test a small bottle of that to start if you want to remain with the Amaco line. Personally when formulating clear glazes (not commercial) one would have to add zinc oxide as part of the recipe else it does not readily occur in the raw resources used to make clear glaze. Link to comment Share on other sites More sharing options...
neilestrick Posted December 29, 2018 Report Share Posted December 29, 2018 Unless someone on the forum is specifically using that clay with a commercial clear glaze, it's impossible to know which commercial clear glaze will work without glazing. Hopefully someone will chime in with their experience. Link to comment Share on other sites More sharing options...
Gojodo Posted December 30, 2018 Author Report Share Posted December 30, 2018 I understand but hope someone may know. Link to comment Share on other sites More sharing options...
Bill Kielb Posted December 30, 2018 Report Share Posted December 30, 2018 51 minutes ago, Gojodo said: I understand but hope someone may know. What I did fail to stress appropriatey is commercial glaze makers do use Zinc as an easy way to get a better fit. The idea of trying the Amaco with zinc is not without merit and might be worth trying a small bottle to make sure. That is of course only If you are not concerned with losing underglaze and / mason stain colors. Link to comment Share on other sites More sharing options...
oldlady Posted December 30, 2018 Report Share Posted December 30, 2018 gojodo, this appears to be a situation where you need to contact Highwater. ask for their technical person and get an answer straight from the expert. they want you to keep buying their supplies so they will give you the correct answer. Link to comment Share on other sites More sharing options...
Gojodo Posted December 30, 2018 Author Report Share Posted December 30, 2018 Good idea, will call this week. Thank you Link to comment Share on other sites More sharing options...
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