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Help With Underglaze And Clear Glaze Compatibility


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Hi all,

 

I'm very new to ceramics and need help with underglaze and clear glaze compatibility. I use Duncan covercoat on bisque with a Colorobbia CLA3 non toxic clear glaze over it. The problem is, the color just doesn't come out right when I use this glaze. I have tried firing at higher temperatures, I have tried putting the covercoat on leather hard clay, firing, then dipping in clear glaze and firing again- nothing seems to work. The color doesn't come out. I have contacted both Duncan and Colorobbia, both seem to say that the two products should work just fine together. When I tried a different clear glaze (lead based) it seemed to work perfectly fine, the color comes out just right. The problem is I do not want to be using a lead based glaze as my pots are for dinnerware! Any suggestions or ideas would be greatly appreciated!
Thanks!!

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have you tried a different clay body? sometimes in my experience i have found clear affects colour based on claybodies.

 

do you have access to mayco clear glazes? or even Duncan's Pure Brilliance clear glaze

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'Zinc has a complicated color response. It can have harmful and helpful effects on blues, browns, greens, pinks and is not recommended with copper, iron, or chrome.'

https://digitalfire.com/4sight/oxide/zno.html

 

It also say that zinc is not really an active flux below cone02-03. The only info I could find on the glaze seemed to have it firing under 1000c, unsure if they are using zinc in the glaze but I would guess there is some in instead of lead.

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Thanks all!

I will try to change clay bodies and see if that works!
Also thanks about the zinc info.

 

The problem is that I unfotunately dont have access to Amaco or Duncan's pure brilliance. It would be very expensive for me to get as I live abroad! Only glaze available in my country is Colorobbia!

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