When I started firing to cone 10 gas in a studio with a strict zero-running-glaze policy, I was crestfallen because I love ash glazes, which tend to run. So I put my thinking cap on. How could I get ash effects with zero chance of any running or dripping?
I experimented with thin washes made of wood ash and various feldspars in different proportions over slips and clay bodies. The first time I knew I was on to something was when I tried one mix over a simple cobalt slip. It gave me a salt-fired effect that reminded me of Lisa Hammond’s surfaces! Upon seeing my pots, people started asking me if I salt fire. I do not.
Even more exciting for me was when I realized that on a humble Cedar Heights Redart slip, I got a beautiful green-ash effect, complete with the lovely rivulets, which are unique to ash glazes. In none of my experiments has there been any running whatsoever.
The wash I settled on is 60% unwashed wood ash and 40% Cornwall Stone. I mix it very thin, only slightly thicker than water, and dip my bisque pots in it. So far, I have had good results over the following slips:
Shino slip (looks salt-like) (see 1)
Domestic porcelain slip with 2% cobalt carbonate and 1% red iron oxide (looks like blue salt)(see 2)
Domestic porcelain slip with 2% copper carbonate (green)
Domestic porcelain slip with 2% red iron oxide and 2.5% borax (looks like glossy green ash)
Cedar Heights Redart slip (looks like matte ash) (see 3)
I have also tried this wash in a wood kiln, fired to cone 11–12, and still no running. I haven’t yet tried using whiting or dolomite to source the calcium instead of wood ash, but I suspect it would work fine (after finding the right proportion). I prefer using wood ash for philosophical and aesthetic reasons, but if you do some testing, I’m fairly certain you can get similar results. Sometimes being forced into confining or otherwise imperfect conditions results in better ideas than you had in the first place.
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When I started firing to cone 10 gas in a studio with a strict zero-running-glaze policy, I was crestfallen because I love ash glazes, which tend to run. So I put my thinking cap on. How could I get ash effects with zero chance of any running or dripping?
I experimented with thin washes made of wood ash and various feldspars in different proportions over slips and clay bodies. The first time I knew I was on to something was when I tried one mix over a simple cobalt slip. It gave me a salt-fired effect that reminded me of Lisa Hammond’s surfaces! Upon seeing my pots, people started asking me if I salt fire. I do not.
Even more exciting for me was when I realized that on a humble Cedar Heights Redart slip, I got a beautiful green-ash effect, complete with the lovely rivulets, which are unique to ash glazes. In none of my experiments has there been any running whatsoever.
The wash I settled on is 60% unwashed wood ash and 40% Cornwall Stone. I mix it very thin, only slightly thicker than water, and dip my bisque pots in it. So far, I have had good results over the following slips:
I have also tried this wash in a wood kiln, fired to cone 11–12, and still no running. I haven’t yet tried using whiting or dolomite to source the calcium instead of wood ash, but I suspect it would work fine (after finding the right proportion). I prefer using wood ash for philosophical and aesthetic reasons, but if you do some testing, I’m fairly certain you can get similar results. Sometimes being forced into confining or otherwise imperfect conditions results in better ideas than you had in the first place.
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