karen terpstra on wed 13 feb 02
Hi Sylvia,
the mouse on my computer is not working this morning so I can't copy
parts of your post....
We do the same thing with our oak wood....vary the size etc.
As far as the salt chamber I am going to try your method. I am new at
all this salt stuff so after 7 firings I think it's time to cut down on
the salt and get rid of the sprayer for awhile. I love to tinker with
new ideas. thanks!
Yea. the black gunk still gives me the willies....
btw. Sylvia, I will probably be around for the 1st part of the
Blacksmith Workshop here but then leave for a trip. Let me know if you
will be in La Crosse at the start.
thanks again,
Karen Terpstra
La Crosse, WI
karen terpstra on thu 14 feb 02
Hi John,
John, I am too inexperience to be able to explain the how's or why's but
just know from our firings of this kiln and a few others that when we
soak at the end, it does several things for us.
1. We get even temperature throughout the kiln. Heat rises during the
soak so the pots even at the very top are nicely flashed. No cold spots.
2. After a soak we load up the firebox, and just let it burn. no
stirring---we don't want unmelted ash anywhere.
3. Our kiln is VERY well insulated and takes a long time to cool and I
think that's where additional flashing occurs. In kilns that we've
fired that cool quickly--we have not seen the same flashing results.
Some where years ago John Neely wrote an incredible article on slow
cooling. He started out saying something like, "Great firing. NO. Great
Cooling! "
I'm not sure testing in our Bailey gas kiln would tell us anything. I
never fire it about cone 10, (11 occasionally). And, it cools quickly
in comparison. We fire to cone 12/13 in the wood kiln. I have never
tried it though and it wouldn't hurt to put some tests in next time.
As far as the black gunk I'm talking about, it is different than "stuff
like coarse emery paper on one side". We've have experienced that many
times! Until I learned how to shut down a kiln. I'm my experience it
is unmelted ash on the cooler side of the pot. I don't mind it on some
of my sculptural work, in fact, I need it on that kind of work. But I'm
trying not to get it on my functional work. It has been taking us
awhile to learn how to load what pieces where.
When the experienced people say it take at least 20 times to fire to get
to know your kiln, I believe them. Patience. Patience....
Karen Terpstra
La Crosse, WI
...It is quite instructive to fire some small unglazed bowls half-filled
with
different wood ashes in a gas kiln and look at the flashing produced.
As
you might expect, different wood ashes give different results varying
from
black gunge to shiny opaque glass to dry white powder. What is more
surprising is the degree and quality of flashing on the inside of the
bowls
associated with different wood ashes - which might give an indication of
which wood to favour in a particular firing. What I found most
interesting
however was that tests using well-washed wood ash displayed little or no
flashing at all. This would support Richard's suggestion that the
flashing
is more to do with soda/potash (the soluble salts removed in the
washing)
than fly ash produced by all that riddling.
But what about the "black gunge" mentioned by Karen Terpstra? I have
suffered from this too - is it associated with excessive fuel/carbon in
the
later stages of the firing? And even worse, what about the rough
(sometimes, but not always, black) stuff like coarse emery paper on one
side
of the pot? It would be nice to have an explanation but I would settle
for
knowing how to avoid these horrors!
John Christie,
Moray, Scotland
karen terpstra on thu 14 feb 02
> All in all, it's a pretty civilized firing and I do spend a fair
> amount of time sitting down listening to it quietly burn.
> Ruth Ballou
> rwballou@home.com
>
Ah Ha! At last! someone who likes to relax in a chair and enjoy!!! I
knew there would be someone out there....
Ruth, I have a zillion questions but have to rush off to school. Would
you keep us informed on your firings with your new kiln? I will email
you with questions about your soda procedure..or.. maybe you will share
with us here?
gotta run..
Karen Terpstra
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