Ian bogus on mon 21 oct 02
Hi everyone, I spent the past 4-6 months trying to get my first kiln running. This past weekend I did my first glaze firing attempting to do a manual soak and controled cool down which was suggested by Mastering Cone 6 Glazes. The kiln is an older model small Amaco kiln, it has two peep holes, but the bottom one is taken by a Kiln Sitter. I put a small Orten cone 6 in the sitter and three larger cones in a cone pack in front of the peep (^5,^6,^7), next time I'll put some more throughout the kiln. Before the pyrometer hit 2000 F the ^5 was tilting, Before it got to 2100 F the cone in the sitter tripped and ^5 was melted completely; ^6 & ^7 were just beginning to tilt (both exactly the same). Instead of overriding the sitter I let it turn off and cool naturally. I have absolutely no idea why ^6 didn't seem to work. I tried four glazes from R&J's book, four simple engobes (I got the recipe from the archives but I don't have it in front of me), and six colorants in
water; all on standard's Brooklyn Red Clay. Waxwing was a beautiful chocolate brown with black flecks, I assume that it didn't break on the edges because there wasn't a soak or controlled cool. Maiol
ica though was really nice when over or under other glazes, but by itself it was rough and almost foamy though it didn't raise off the surface of the clay. When I mixed the glazes I put way too much water in and had to scoop off the excess when it settled. The Maiolica's water was the only one that was cloudy, do I decided to save it. Of the engobes the Yellow Iron Oxide Ochre turned dark brown and the Black Iron Oxide was reddish brown. The colorants in water I think I mixed up the order because the one I had labeled BIO was dark purple which looks as if it was switched with the one labeled Manganese Dioxide which was pitch black. The YIO and RIO I think were switched also, though the one I think it YIO barely showed up at all, but was NOT yellow. The Copper Carbonate is dark grayish. If anyone has any thoughts on any of this I would greatly appreciate it! Thanks,Ian
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Lily Krakowski on tue 22 oct 02
Let me be general (l.c. "g", believe me) because more than one newbie might
be affected.
What is a small kiln??????? A small electric kiln can be 12"x 12"x 12" a
test kiln can be smaller so what do you have in mind? A small woodburning
kiln probably is no smaller than 3'x 3'x 3'.
As far as I know--limited indeed- a controlled cool down in an older kiln is
quite a project as they are not insulated enough to allow for the control
part. " Firing down" i.e. keeping the kiln on medium for a while and then on
low, gives, can give, dubious results.
It is common to have to use a higher number cone in the sitter than on the
shelves. As a rule one putters with this till one gets exactly the
maturation one wants in the glazes. In my kiln I use bars not junior cones,
unless I want to achieve something different from the norm.
To explain. By being bars and the same thickness all over, bars in the
sitter are very accurate as far as temp goes. By being cone shaped the
junior cones permit one to adjust the temp a bit. If the cone is inserted
so the rod rests on the thinner end, the kiln will go off sooner than if the
rod rests on the fatter end. yes?
so to get the c. 6 I want, I use a c.7 bar.
As to pyrometers. A friend used to say: Never trust a man who wears brown
shoes with a blue suit. Ok. Crass rule of thumb: I do not trust pyrometers
and certainly would not trust one that came with an old kiln.
As to your glazes. This is not funny. Mixing glazes without paying total
attention is a pure waste of money, unless you are at the stage where you
know so well what you are doing you can take chances. Talk to me in ten
years.
I do not even want to know what scooping the water off means. If you do
have too much water in a glaze let it settle out at least 24 hours and
probably more if you have added any of the materials that keep the glaze in
suspension. Then syphon excess water off very very carefully so as not to
pick up any of the teensy particles that may be floating about. Some of
your glaze problems may have been caused by your scooping off water and
failing to stir the glaze properly after the settling/scooping bit.
Ian bogus writes:
> Hi everyone, I spent the past 4-6 months trying to get my first kiln running. This past weekend I did my first glaze firing attempting to do a manual soak and controled cool down which was suggested by Mastering Cone 6 Glazes. The kiln is an older model small Amaco kiln, it has two peep holes, but the bottom one is taken by a Kiln Sitter. I put a small Orten cone 6 in the sitter and three larger cones in a cone pack in front of the peep (^5,^6,^7), next time I'll put some more throughout the kiln. Before the pyrometer hit 2000 F the ^5 was tilting, Before it got to 2100 F the cone in the sitter tripped and ^5 was melted completely; ^6 & ^7 were just beginning to tilt (both exactly the same). Instead of overriding the sitter I let it turn off and cool naturally. I have absolutely no idea why ^6 didn't seem to work. I tried four glazes from R&J's book, four simple engobes (I got the recipe from the archives but I don't have it in front of me), and six colorants i
n
> water; all on standard's Brooklyn Red Clay. Waxwing was a beautiful chocolate brown with black flecks, I assume that it didn't break on the edges because there wasn't a soak or controlled cool. Maiol
> ica though was really nice when over or under other glazes, but by itself it was rough and almost foamy though it didn't raise off the surface of the clay. When I mixed the glazes I put way too much water in and had to scoop off the excess when it settled. The Maiolica's water was the only one that was cloudy, do I decided to save it. Of the engobes the Yellow Iron Oxide Ochre turned dark brown and the Black Iron Oxide was reddish brown. The colorants in water I think I mixed up the order because the one I had labeled BIO was dark purple which looks as if it was switched with the one labeled Manganese Dioxide which was pitch black. The YIO and RIO I think were switched also, though the one I think it YIO barely showed up at all, but was NOT yellow. The Copper Carbonate is dark grayish. If anyone has any thoughts on any of this I would greatly appreciate it! Thanks,Ian
>
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Lili Krakowski
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Be of good courage....
Snail Scott on tue 22 oct 02
At 09:20 PM 10/21/02 -0400, you wrote:
>the one I had labeled BIO was dark purple which looks as if it was
switched with the one labeled Manganese Dioxide which was pitch black. The
YIO and RIO I think were switched also, though the one I think it YIO
barely showed up at all, but was NOT yellow. The Copper Carbonate is dark
grayish.
Don't sit there second-guessing yourself on the
basis of decanted glaze-water. Test-fire the
stuff and you'll know which is which. Then label
it accordingly. (Don't forget to mark your test
pieces!)
-Snail
Marianne Lombardo on tue 22 oct 02
Ian;
I have an old kiln and have to cool down slowly manually. If you go to the
Clayart archives and search for a message from me with the subject Mastering
Cone 6 Glazes you can find a description I posted on what works for me with
my kiln. Perhaps that may help you a bit with the firings.
I now put a cone 7 in my kiln sitter. As Lily mentioned, a pyrometer isn't
going to be exact. But I do find it to be a big help in manually cooling
down because at least you can figure out how fast/slow you are cooling down.
But as far as your glaze mixing goes, there really is no margin for error.
You need to weight ingredients very carefully, write down each step and be
very precise and don't get anything mixed up.
If you are using red clay perhaps the iron content is affecting the glaze
colors somewhat. It might help to try the recipes again (mixing new
batches) and use a white stoneware, or porcelain.
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
Ron Roy on sun 27 oct 02
Two comments on the following - controlled cool down is even more important
in an older kiln - they tend to leak heat more than new kilns so they cool
down faster - if you can get to cone 6 then you can sucessfully cool down
slow - especially of you have infinit switches - even if you have low.
medium and high switches. If you only have on/off switshes - enough of them
you can still slow cool.
In order to do this it is a great advantage to have a pyrometer - first of
all - if you use lage cones - you will get some idea aboout how accurate it
is and can make the mental adjustment - more importantly - you can tell if
the temp is staying the same - rising and falling and how fast. All of
these functions are useful in getting proper firing results.
I do not have a blue suit - don't have a suit period - do have brown shoes.
Just keep in mind - a sitter is a safety device but not a proper toll for
firing clay and glazes - a pyrometer helps you understand what is happening
in the kiln - a cone tells you how much heat work has been done.
Controllers tell you what is happening - is a safety device and much more -
if you fire with a controller you still need large cones to measure heat
work.
RR
>As far as I know--limited indeed- a controlled cool down in an older kiln is
>quite a project as they are not insulated enough to allow for the control
>part. " Firing down" i.e. keeping the kiln on medium for a while and then on
>low, gives, can give, dubious results.
>As to pyrometers. A friend used to say: Never trust a man who wears brown
>shoes with a blue suit. Ok. Crass rule of thumb: I do not trust pyrometers
>and certainly would not trust one that came with an old kiln.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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