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Using Copper Carbonate And Cobalt Oxide

Tyler G

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I found a small ziplock bag of each of these. I don't really intend to make functional ware, but I do realize that these chemicals are hazardous in their powdered form as well. 


I would like to make a slip or add them to a base glaze or something, but was not sure where to start with these...any advice?




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do you have any recipes? Adding copper carb to glazes usually begins with amounts like 0.5 for copper red in reduction to maybe 4% for greens but that depends on the bases.

Cobalt Oxide is much stronger. 0.5 will give a pale blue. If you have magnesium in the base such as Dolomite, it tends to go lavender.

Slips use more than glazes. You can use slip from throwing and maybe add a little flux.

Get some recipes for whatever recipes you are using.


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Safety first: copper isn't hazardous. Cobalt is kinda toxic and I avoid skin contact.


How to use:

Copper can be used in a slip form to create green to an intense metallic black that would leach in water. I've made copper carbonate slips with between 10% and 50% dry weight.


Cobalt oxide produces the intense "blue willow" color. I keep mine cobalt oxide solutions very water and use like 0.5 gram cobalt and maybe 1 gram china clay. The darkness/intensity of the color varies with thickness. I paint this to bisque ware. For for elaborate designs I will re-fire the bisque to set the cobalt -- makes it easier to apply glazes perfectly when I don't have to worry about smudging cobalt decorations.

Cobalt oxide can also be add to pretty much any glaze to give a speckling of blue. This can be good in some white glazes.

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"Flour would be a respiratory hazard in the studio" he said grumpily.



Yeah, I wouldn't purposely breath either of them in. Avoiding making airborne dust is more important than wearing a mask if you ask me. Or the question really could be when do you stop wearing the mask? After the bag is put away? After an hour?

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Copper toxicity is known, some potters do not use copper containing glazes in interior of pots, or get leaching test before doing so

Just saying

I guess you know this

Anyway, too nice a day to be grumpy, many greater hazards in my shed yes. Shooed a tiger snake out, now they're not toxic to eat but are toxic if they bite you.ah ironies

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