Friday, November 13, 2009

Plink




The title above is a link to a short video - filmed,edited and posted from my iphone - of the approved technique for removing pedestals from crystal glaze pots after firing. If you sand bisced pot-bottom and stand and attach with kaolin/glue mixture,the parts should separate with that satisfying and informative Plink. If you keep on heating,the pot will break shortly thereafter. How do I know? Guess..
Top picture: improvised camera support.
Middle: Testing remains of last year's glazes - they still work. Some opinions hold that these glazes have a limited shelf-life;I've never found that to be the case.
Bottom; left - blue crystal glaze with no titanium;there are no 'seeds' for the zinc to form around,so just masses of micro-crystals. Right - same glaze with 25% of it's titanium; looks like too much cobalt [too blue],but some blue crystals with clear blue background. This is what I was hoping for - a couple of years ago I had a beautiful blue crystal glaze,but subsequent batches gave me only blue with a tan background - nice,but not as. Numerous experiments got nowhere,then last Summer it suddenly popped into my head that I had run out of titanium when mixing that particular blue/blue batch and forgotten to write down the difference. Now I think we're back on track - a bit more titanium,a bit less cobalt,maybe a smidgen of manganese for the colour...
By the way,my joy at getting 3/3 sinks from the bisc last week was premature;my friend Alan pointed out a crack to me that evening,running smack through my signature stamp on the outside wall,trim to base. I've had this happen before,and even took care to stamp the sinks especially gently,but it wasn't enough.Next time I'll carve my signature - or maybe not sign at all. There can't be that many other people making crystal-glazed porcelain sinks. The one that cracked [I gave it to a neighbour for a planter] was on the bottom of the bisc kiln,although raised up a little - another contributory factor,I think.

1 Comments:

Blogger SpiderZ said...

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5:50 PM  

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