Alisa and Claus Clausen on wed 7 jul 99
As I venture into trying once firing, I begin to speculate on the =
=22horrors=22 I
may have the pleasure to encounter along my experimental way=21 Seriously, =
I do
have the following question or rather concern.
I can recall pouring slip into the inside of bonedry greenware and as it =
dryed,
I saw the pot spring with hundreds of cracks. Did not repeat proceedure, =
rather
always use slips on wetter greenware.
Does this not happen when GLAZING bone dry greenware? Or if it is a hazard,
what does one do to prevent it as best as one can?
I am interested by the writtings of Dean, on converting bisqued to a single =
fire
glaze.
=22Just take a bone dry piece and dunk it in your glaze or spray it=22
Does it now crack up? If not, why did it do so with slip? Because the slip=
is
thick and clay-ey, greedy for water, and maybe absorbs more than the more =
watery
glaze? My imagination working hard..a very hazardly guess.
Also Dean say also that =22most of the flaws that I=F8ve encountered show up=
the
time the glaze is dry on the pot=22
Do you mean the pot sprang?
Can you add 1-2=25 bentonite to any recipe to avoid =22problems=22.
Lastly, Dean says =22How you apply the glaze is an important consideration =
esp.
if lyour caly body is very open. Spraying is safest. Avoid glazing inner =
and
outer surfaces at the same time=22 That sounds different from the above, =
=22just
dunk it your glaze=22.
I am again thinking that spraying gives the lightest surface, therefore the
least amount of absorption, thus success.
I certainly appreciate any feedback on my speculations.
Many thanks in advance Dean and any others with input.
Alisa
Jenny Lewis on sat 6 may 06
Hi Neil
I thought I'd reply offline as Clayart is doing weird things again, and I
haven't received the digest regularly for a few days. So here goes.
I'm not an expert on raw glazing, but I did a weekend workshop with Fran
Tristram - her book is very helpful by the way, worth a look if you haven't seen
it yet. I have also tried it in my own studio.
What I learned from her and therefore did for myself, was to glaze the work
bone dry. Quick spray on the outside with a sprayer bottle (like you use to
mist pot plants) and then glaze the inside. Leave to dry, then glaze outside.
She uses a spray booth for the outside of her work which incidentally is
nothing like the pictures in her book! She changed style after it was published.
I found that the bone dry wear is pretty tough, and even if you drop a pot
into the glaze bucket and have to fish it out again, it doesn't disintegrate.
Guess how I know this....
Big thing to consider is the glaze recipe itself. Needs at least one-third
(I think, but check in the archives) of ball clay. Of course I wanted to see
what would happen if... so I tested a couple of glazes that did not have enough
clay content and now I know - they just fall right off the pot! Messy kiln
shelves were avoided, because I had put the test pieces onto pancakes of clay,
just in case. Just as well.
The firing schedule was like a bisc, perhaps even a bit slower at first even
though I was sure they were completely dry. Then when temp reached, glaze
fire schedule.
I haven't continued with the raw glazing mainly because too many of my
favourite glazes just don't have the right clay content. If I get into some major
glaze testing with single firing in mind, then I would like to try again.
Also, must confess, I'm clumsy when glazing! So I've gone back to two firings,
for the moment.
Hope some of this helps!
Cheers
Jenny Lewis
in Eastleigh, Hampshire, UK
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