Randy McCall on mon 25 apr 05
Thanks for all the Firing Disaster responses. Like a lot of others I =
have refired before without any problems, but this time I certainly must =
have gotten a pot too wet. Usually I just add alittle glaze here or =
there to bring out some accent when refiring. I do know one pot though =
that got washed off and I think that was the one.
I had gotten a message from the previous firing when a piece cracked and =
shattered a bottom without a blow out. Should have paid attention =
rather than right it off. A real lesson learned. Hope others will take =
heed from the responses. The pot in question I think though had had =
multiple firings to bad I didn't trash it, but that's the way it goes.
Never again will I risk such a disaster.
Thanks for all the responses it has been a very enlightening experience =
to say the least. I wonder why I only got two response and had to read =
the others in the archives?
Cat Jarosz on tue 26 apr 05
In a message dated 4/26/2005 4:03:16 AM Eastern Daylight Time,
ranmcc@MSN.COM writes:
Thanks for all the Firing Disaster responses. Like a lot of others I =
have refired before without any problems, but this time I certainly must =
have gotten a pot too wet. Usually I just add alittle glaze here or =
there to bring out some accent when refiring. I do know one pot though =
that got washed off and I think that was the one.
Hey there Ranmcc and any other interested parties..
been reading about Cristobalite last few nites and with the recent
discussions on contraction and expansion... with sufficient time Crystobolite
forms 2012-2350 F (3-4 hrs) this is when the free silica changes to
cristobalite... too much will be formed if you stay at those high temps for to long .
this is cumulative , so repeated exposure to high temps , such as when a
pot is refired, should be avoided.. Cristobalite contracts 3% and thats alot
of stress on a pot.. so the more cristabolite the more contraction ...
each time you fire you get more and more cristobalite that is going to
contract each time ... russian roulette with the multiple firings..
This is just another possibility along with what has been said on the
subject.. So even if you drive all the water out slowly and can avoid that
type of BLOW UP this cristobalite will still keep forming more and more with
each refire and eventually will have a nervous contraction breakdown..
ps even if you dont blow up the pot with excessive refires if this is a
functional pot that you will expect to cook with know that the pot may DUNT
either during the kiln cool down or later during ordinary usage...
ps source of imfo from John Britt's note book.. ( he is a clay arter too
)
Cat Jarosz in the cool mnts of NC..... who is not even started to pack
pots for the Sanford show yet... got one more load in the kiln to get out
late tonite.. got a good start on putting aside the wholesalers goods and
then see what I got left and what I want to bring and what stays home..
got a small van and a huge booth and this is a 5 hrs away from home show..
I"ll be bustin buns today tomorrow and thursday.. but I have been
bustin buns for 2 months so nuttin new.. pps excited to see the clay art
potters doing the show when not busy setting up or during the show, would be
great to meet after set up or sat nite or early ams before it opens and if
not busy getting ready... I get distracted soooo easy
http://www.guildcrafts.com/cat/
V)''(V woof & >^..^< mew; Chicks with beards rule !!!
(_o_)
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