[Clayart] Boron glazes

Dick White tgrcat at verizon.net
Mon Jan 4 00:01:37 EST 2016


Thanks for jumping in. You probably don't suspect how closely you just 
put your finger on the root of the issue. You may have noticed in Bill 
Schran's recent tribute to Judy Hesselberth that he mentioned a weekend 
visit he and several students had to John and Judy's house many years 
ago for a semi-private workshop in glaze theory using your excellent 
book (which I sometimes lovingly refer to as the RonJohn glazes) and his 
GlazeMaster software. I was privileged to have been one of the students. 
It was an awesome experience, John and Judy were wonderful hosts and she 
will be missed. Somewhere in the midst of all that information, which 
was completely new to me at the time and I could hardly get my head 
around, John made a passing reference to the possibility that Waterfall 
Brown did what it did because of the uneven mixing of the boron and 
silica glasses. That brief comment has just been sitting dormant in the 
back of my head until recently when I began wondering why certain glaze 
combinations are so interesting when layered and others are not. A quick 
look at the UMF for Waterfall shows that 1) the boron is .77 (which is 
well beyond typical B levels in ^6 glazes, more like the level found in 
earthenware glazes); and 2) the Al and Si levels at approx. .3 and 4, 
respectively, are quite healthy for a durable ^6 glaze. Fitting that 
into my current hypothesis, you made a double play with that recipe - 
both a high boron glass and a high silica glass in the same bucket.


Ron Roy wrote:
Hi Dick,

I'm interested in knowing more about this - can I help in any way?

A good example of a high boron glaze is our Waterfall glaze - in
Mastering cone 6 glazes (Hesselberth/Roy)

I don't work at cone 6 but can do some testing - John does work at
cone 6 though. His wife just died so we should not bother him right
now but he may also be interested later.


Ron Roy
ronroy at ca.inter.net
Web page ronroy.net

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