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few firing questions

updated sun 8 nov 98

 

Jan on tue 3 nov 98


Hi,

I use a Skutts 1018 with an envirovent for my firings.
I only bisque fire at 03 and glaze fire at 05.
The firing cycle is like this -
1 -2 hours on Low
2 hours on Med
then on high till finish which usually will take another 2 hours.

Questions:

1. Where is the best place to place plates in the kiln? i have broken 4
plates on the top shelf during glaze firings..what do you think happened?

2. For crystal glazes, again is there a 'better' place to put the wares in
the kiln? like bottom shelf..etc? pls explain why? I found some of my
glazes ran so much at he bottom shelf and last week one got stuck to my
shelf!!


3. If i had bisqued fire a stoneware clay at 03, is it possible for me to
glaze the ware, using a glaze which says it must be used on a bisqued ware
at 018. If i do glaze this ware, what might happen in the firing?

4. If i have stoneware clay of diffirent types, which is not packaged by
some famous brands, rather, kinda not sure what is inside the clay..etc but
only knowing it is stoneware, what are the best ways i could test fire the
clay and also glazes on them without making too many terrible mistakes..?
like melting clay..etc

thank you!!!!

Jan

Christine Avery on thu 5 nov 98

Jan:

What kind of clay are you using?
When I read your questions it led me to believe you are using a stoneware
body. It has always been my understanding that stoneware should be bisqued
at 06 and then glazed ^4 -^10 depending if it was a mid-range or high fire
otherwise it doesn't vitrify.

Earthenware on the otherhand is bisqued at ^O4 and glazed at ^O5-06

I teach high school and the kids are ALWAYS mixing the clay up. I use
stoneware and earthenware. When we had to test it last year I just made
small tiles and put them in a junk bisqued bowl (one that I knew was made
from high fire stoneware) so if they melted just the bowl was wrecked
I then stuck it in at cone 10 (they survived) so I

Also I have never heard of anything going on ^O18 bisque so would be very
curious to hear more about this. I have some overglazes that get put on
fully glazed ware then fired at cone 018

Re the plates at the bottom.
Have you ever set some test cones on the different shelves to check the
true firing temperatures sometimes it can vary alot. (My pyrometer is off
100!F by the time it gets to ^9 so I never trust it or the auto-shutoff-I
know I need a new pyrometer but where's the money?)

Re: bisqueing at a different temp then required for the glaze.
When I first started a few years ago I didn't know certain things
"shouldn't" be done. We took junk pots and experimented. one thing we did
is we wanted stoneware to be totally mature so we bisqued it to a ^9 then
put a decorative ^O5 slip trail design on it and covered it with a ^06
clear. Some who knew the "rules" said it wouldn't work. It came out
beautifully. In fact the student who did it ended up using that technique
again when she went on to major in ceramics. Not all glazes will stick some
will crawl etc. etc. and they take longer to dry. So you have to do a
little testing.
I put a thin coat of gum arabic on the pot and let it dry before glazing.I
do this if I ever need to reglaze a pot for some reason. remember I teach
high school and consider myself more of a trouble shooter than a teacher:)

Let me know how everything turns out

Christine
from nodak where the weather is still nice

Penny Hosler on sat 7 nov 98


>is we wanted stoneware to be totally mature so we bisqued it to a ^9 then
put a decorative ^O5 slip trail design on it and covered it with a ^06
clear. Some who knew the "rules" said it wouldn't work. It came out
beautifully. In fact the student who did it ended up using that technique
again when she went on to major in ceramics. <

Christine,
Re the above, I just got an e-mail from Donna Young -- she decorates sinks
by using ^06 low-fire glazes on ^8 bisque. Beautiful stuff, at
www.donnayoung.com, but I'd been told that wasn't supposed to work either.
I think I'll just quit believing
everything I read....now I'm more confused than ever.
Penny in WA