Elaine Stutt ) writes:
"DKat" ) writes:
So heres the deal - most of the glazes I tested worked just fine except for
the lips where at least half of them simply flaked off. I hate to put these
pots through any more stress so I'm going to try painting on the lips a very
thin coat. Do I do this by thinning down the glaze or what? Do I add corn
syrup to the glaze and if so in what ratio? Thanks, Donna

I've done some raw glazing and I took some notes on it from a book.
Naturally, the notes aren't here. I think I remember that for flaking
on the lip, you may need to reformulate the glaze. It may be a
simple change i.e. instead of kaolin use ball clay as it's more elastic.
If the recipe doesn't have kaolin...I'll try and pick up my notes.

Finally found the notes. For crawling on the lip, it suggests a thinner
glaze application. For flaking it doesn't mention lips but for minor
flaking: if the flaking happens when touched, add 3 percent binder;
if it flakes before it's touched add more. Binder I guess means gum,
possibly sugar.

That's from Dennis Parks book on raw glazing.

For myself, I find thickness of glaze a real challenge. I don't
fire that often and if the glaze has evaporated at all it's hard
to figure out how much water to add. I try to document it with
a hydrometer. Note that bisqueware usually wants a thinner glaze,
so you can't use the same vat of glaze for both.

The only time I tried syrup it was icky. But it was for a re-glazing
and I may have used too much.
Elaine

In the refiring, I got uneven areas almost blobs of new glaze on the
old glaze. I could have used to much syrup or it could be that the
two firings were in differant kilns. The second may not have been hot
enough to really melt the glaze smooth. Don't know.

I also have Fran Tristram's "Single Firing" but haven't done any
glazing since I got it. One question for UK posters or for anyone.
The local supplier here in western Canada won't/can't supply any
lead frits or bi-silicates. Every low-fire glaze in the above book
has lead. It seems to be a current book, c'96. Is lead use still
common in the UK? In the rest of North America?

Well, common for small functional potters, common for sculpture,
common in universities? I get the impression that other frits
have taken over.

Elaine