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glazes - from cone 6 to cone 8

updated tue 3 apr 01


Ken Chin-Purcell on mon 2 apr 01

Maybe all you need is a few good glazes, but for
those of us developing our own palette it can still be a
challenge to find those winners.

There are of course loads of cone 6 recipes to take
as starting points. Here is how I take a glaze from
cone 6 to cone 8 within a glaze calculation program:

1) Reduce boron by about 0.2 moles.
2) Raise alumina by 0.05 moles or silica by 0.5 moles,
while holding the Si + B to Al ratio constant.
3) Let calcia (and magnesia, if present) drift up by 0.05 moles.
Let KNaO drift down, as needed.

In tests I've had some successes and lots of duds, but I
usually get "good glass" without excessive runs using the above.
I fire in an electric kiln so that cone 8 almost touches
down and cone 9 is at 2 o'clock.

Glaze gurus: any comments or tips to add to this?

My cone 8 recipes can be found on my web site under "technical info".

-- Ken Chin-Purcell