Jocelyn McAuley on tue 2 jul 02
Hi Paul,
If you are interested in this subject enough to make another book purchase
I would suggest Tom Coleman's book of glaze recipes "Glazes I Use". He
has an insightful section of copper red tricks that are really
interesting.
Tom also has a Studio Potter article online at:
http://www.studiopotter.org/articles/art0003.htm
I would also suggest looking through the clayart archives as well as doing
some generic searches online to find a variety of firing styles for this
glaze.
Another good search tip would be to look into Pete Pinnell's Clay Times
article about firing for copper reds. I believe it's from a '98 issue?
Good luck
On Tue, 2 Jul 2002, Paul wrote:
> What is the best way to minimalize the loss of copper in copper red glazes?
--
Jocelyn McAuley ><<'> jocie@worlddomination.net
Eugene, Oregon http://www.ceramicism.com
Paul on tue 2 jul 02
What is the best way to minimalize the loss of copper in copper red glazes?
I have done lots of research and testing on the subject but am still
learning, and would like to know what works best for those that get
consistent copper reds. I have gone to great lenghts to place them away from
direct flames and this usually works; and also not to over-fire them. Also i
have worked a lot to get an thorough reduction throughout the kiln to make
sure all the pieces get a good body reduction, and this has helped as well.
But then i have heard that too much reduction can ruin them, but i do not
know if this is true. But then i met a potter who said he did only one
firing in his life with copper reds: he filled the whole kiln with them,
fired the whole thing in a NEUTRAL atmosphere (no body reduction at all and
using an oxyprobe to prove it), and came out with a full load of more or
less "classic reds," just like the magazine ad. Can anyone explain this? He
had an updraft fiber kiln with venturi burners.
Finally, i have heard of people spraying a clear glaze that melts at a lower
temperature over the copper red, to seal over the copper and keep it from
volatilizing. I am considering this as well, but am interested in hearing
what others think and if this is really needed.
Any input would be greatly appreciated. thanks.
Paul
Ron Roy on wed 3 jul 02
Hi Paul - I think you already may have the answer you need - slow cooling
to let the ruby crystals develope.
You can refire one of those white pots to a low bisque temp - it's called
striking - that may give the crystals the time they need to form.
RR
>What is the best way to minimalize the loss of copper in copper red glazes?
>I have done lots of research and testing on the subject but am still
>learning, and would like to know what works best for those that get
>consistent copper reds. I have gone to great lenghts to place them away from
>direct flames and this usually works; and also not to over-fire them. Also i
>have worked a lot to get an thorough reduction throughout the kiln to make
>sure all the pieces get a good body reduction, and this has helped as well.
>But then i have heard that too much reduction can ruin them, but i do not
>know if this is true. But then i met a potter who said he did only one
>firing in his life with copper reds: he filled the whole kiln with them,
>fired the whole thing in a NEUTRAL atmosphere (no body reduction at all and
>using an oxyprobe to prove it), and came out with a full load of more or
>less "classic reds," just like the magazine ad. Can anyone explain this? He
>had an updraft fiber kiln with venturi burners.
>Finally, i have heard of people spraying a clear glaze that melts at a lower
>temperature over the copper red, to seal over the copper and keep it from
>volatilizing. I am considering this as well, but am interested in hearing
>what others think and if this is really needed.
>Any input would be greatly appreciated. thanks.
>Paul
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Dave Murphy on wed 3 jul 02
Paul:
I currently wholesale a copper red combination and now (after alot of hair
pulling and trying different voodoo) get consistent and solid results
everywhere in the kiln. I have a 60 cu ft propane gas IFB kiln with three
stacks back to front. I used to stack the reds in the back and across the
top to prevent impingement and to get early reduction as well as to prevent
them getting too hot. Now I want that space for shinos the reds had to go
everywhere else and I started reducing earlier (1650F). I reduce throughout
the balance of the firing, I do not use a probe but when I check a top peep
the flame licks out for a few seconds and then goes back in and the
atmosphere in the kiln is murky.
The single most effective and what I consider the clincher for me though is
the "relight" of the kiln after it has cooled to 1800F. I then fire it back
up to 2000F (takes about 1.5 hours) and then let it cool (damper shut for
one hour and then opened 3 inches). The reds have a depth that is kickass
right to the claybody and the colour even in the cone 10-11 is all there!
I know that there are lots of other "only way to do it" methods, this works
for me. Good luck.
Barbara Murphy
Waterloo County Pottery
Waterloo Ontario
Canada
Ned Ludd on thu 4 jul 02
Dear Lusting-After-Copper-Redheads
My kiln partner, a pro to his eyeballs, has fired loads of copper
reds on porcelain for years: it's all he does. He fires to cone 11,
in an old, not-too-well-insulated 18-cubic foot powerful gas kiln
built of softbrick, a downdraft with 4 venturi burners. He does not
reduce that heavily, does not use a 'probe or a pyro, only cones. He
fires by his senses in 7 or 8 hours - in summer here where it's hot
and dry. Winter, he takes a little longer.
His results are consistently excellent: from Fire Engine red to a bit
more purplish, as he chooses. He prefers the former, but some of his
galleries keep ordering the purpler, so...
However, he fast cools. Doesn't even clam his burner ports, just his
spies and the damper, which doesn't completely block the flue. He
starts unbricking the door of the kiln just nine hours after cone 11
is hard over.
Not my taste... but I have to say he loses hardly any pots.
good luck
Ned
RR wrote:
>Hi Paul - I think you already may have the answer you need - slow cooling
>to let the ruby crystals develope.
>
>You can refire one of those white pots to a low bisque temp - it's called
>striking - that may give the crystals the time they need to form.
>
>RR
Paul wrote:
> >What is the best way to minimalize the loss of copper in copper red glazes?
>>I have done lots of research and testing on the subject but am still
>>learning, and would like to know what works best for those that get
> >consistent copper reds.
Ron Roy on fri 5 jul 02
Hi Ned,
Thanks for this post - It's probably his glaze - some glazes will
recrystallize even in a fast cool. It depends on a number of factors. Other
glazes need a slow cool - again because of how they are formulated. Some
copper glazes do need to be struck or slow cooled to get the crystals to
form.
Don't ask me which is which cause I have very limited experience with
copper reds.
RR
>My kiln partner, a pro to his eyeballs, has fired loads of copper
>reds on porcelain for years: it's all he does. He fires to cone 11,
>in an old, not-too-well-insulated 18-cubic foot powerful gas kiln
>built of softbrick, a downdraft with 4 venturi burners. He does not
>reduce that heavily, does not use a 'probe or a pyro, only cones. He
>fires by his senses in 7 or 8 hours - in summer here where it's hot
>and dry. Winter, he takes a little longer.
>
>His results are consistently excellent: from Fire Engine red to a bit
>more purplish, as he chooses. He prefers the former, but some of his
>galleries keep ordering the purpler, so...
>
>However, he fast cools. Doesn't even clam his burner ports, just his
>spies and the damper, which doesn't completely block the flue. He
>starts unbricking the door of the kiln just nine hours after cone 11
>is hard over.
>
>Not my taste... but I have to say he loses hardly any pots.
>
>good luck
>
>Ned
>
>
>RR wrote:
>>Hi Paul - I think you already may have the answer you need - slow cooling
>>to let the ruby crystals develope.
>>
>>You can refire one of those white pots to a low bisque temp - it's called
>>striking - that may give the crystals the time they need to form.
>>
>>RR
>
>Paul wrote:
>
>> >What is the best way to minimalize the loss of copper in copper red glazes?
>>>I have done lots of research and testing on the subject but am still
>>>learning, and would like to know what works best for those that get
>> >consistent copper reds.
>
>
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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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