Donn Buchfinck on fri 23 oct 98
first I think before anyone starts to post a problem they should send a copy
of the recipe along
second I think people should look at their glazes, and if there is not tin
oxide in the glaze or one has substituted zircopax or some variation of it,
this will cause problems
it has been my limited experience that copper reds have to have tin oxide in
them to work
I think it is also time for people to look at what/how they are firing their
kiln, and the application of the glaze to the ware, sometimes people apply it
too thin on the pots
a simple rundown on the firing schedual would help, when do you do body
reduction, do you reduce all the way through, oxidize in the end, reduce hard
in the end?? These are important cosiderations when trying to get the glaze
to work
looking under a microscope is great but I think we have to solve the problems
so we can have money in the bank
Do not skimp on the materials
and put the glaze on a good quality porcelain body or slip
Lewis Red
Cornwall 30
BaCo3 49
Silica 10
Tin Ox 5
CuCo3 1
Bentonite 3%
Oxblood red this I have used with no problems
Neph sye 42
Custer 9
kaolin 2
silica 23
colemanite 13
whiting 11
copper carb .75%
tin ox 1
bent 3%
Petes copper red from Peter Pinnell can't do any better than this I would
try this one first
Custer 73
Gerstly borate 10
whiting 12
flint 5
tin ox 1
copper carb .3%
Val Cushing vampire red
k-200 spar 26
frit 3185 5
whiting 16
barium carb 12
soda ash 5
ball clay 4
EPK 4
flint 28
copper carb .5%
tin ox 3%
Donn Buchfinck on sat 24 oct 98
sorry everyone the cone for the glaze recipies is
c 10
and it is hard to get a copper red at cone 6 oxidation
I think people put something in the glaze for the oxidation firings
like fine mesh silicon carbide to reduce the glaze
if you fire the glaze in oxidation the glaze will come out apple green
Donn Buchfinck
Jeff Lawrence on mon 26 oct 98
Donn Buchfink wrote:
>first I think before anyone starts to post a problem they should send a copy
>of the recipe along
>
>second I think people should look at their glazes, and if there is not tin
>oxide in the glaze or one has substituted zircopax or some variation of it,
>this will cause problems
>
>it has been my limited experience that copper reds have to have tin oxide in
>them to work
>I think it is also time for people to look at what/how they are firing their
>kiln, and the application of the glaze to the ware, sometimes people apply it
>too thin on the pots
>a simple rundown on the firing schedual would help, when do you do body
>reduction, do you reduce all the way through, oxidize in the end, reduce hard
>in the end?? These are important cosiderations when trying to get the glaze
>to work
>
>looking under a microscope is great but I think we have to solve the problems
>so we can have money in the bank
Donn,
I think you're missing the point of this thread, which is to take a fresh
approach to the problem of reliable beautiful copper reds as taken by a very
gifted scientist. Money in the bank doesn't have anything to do with it as
far as I can see -- rather consider that same pursuit of the beautiful
you've claimed as your artistic raison d'etre. Ray is just fascinated by the
problem and I am fascinated by what he comes up with. Joy of learning, that
kind of thing.
Including all previous posts to a thread is a waste of bandwidth, inmho.
Sorry you missed the beginning. When I'm at a breaking point, hopefully
resting on roseate laurels, I'll post a full report.
Until then, FYI I'm firing to ^6, taking an hour and a half or so between
900-1000F, starting a medium level of reduction at 1100 (.5-.65 on my
Oxyprobe) and maintaining it to temperature (2245F on my pyrometer), 1/2
hour soak in reduction followed by 20 minutes soak oxidation (per Tichane's
suggestion). This was today's schedule.
As has been said, recipes travel poorly. In my experience they are always
particularly disgruntled when forced to visit my neck of the woods. Read
TOny Hansen's sermons against "trafficking in glazes" to help you cast away
those paper crutches. Contrary to your tin experience, the best reds I've
gotten to date had no tin. Any theories?
Jeff
Nalis W. Giles on mon 26 oct 98
What cone should these glazes be fired to? Are you brushing, dipping or spraying
on the glaze? Are you useing heavy reduction? Are these good glazes to use for
raku? Thanks for the info.
Donn Buchfinck wrote:
> ----------------------------Original message----------------------------
>
> first I think before anyone starts to post a problem they should send a copy
> of the recipe along
>
> second I think people should look at their glazes, and if there is not tin
> oxide in the glaze or one has substituted zircopax or some variation of it,
> this will cause problems
>
> it has been my limited experience that copper reds have to have tin oxide in
> them to work
> I think it is also time for people to look at what/how they are firing their
> kiln, and the application of the glaze to the ware, sometimes people apply it
> too thin on the pots
> a simple rundown on the firing schedual would help, when do you do body
> reduction, do you reduce all the way through, oxidize in the end, reduce hard
> in the end?? These are important cosiderations when trying to get the glaze
> to work
>
> looking under a microscope is great but I think we have to solve the problems
> so we can have money in the bank
>
> Do not skimp on the materials
> and put the glaze on a good quality porcelain body or slip
>
> Lewis Red
> Cornwall 30
> BaCo3 49
> Silica 10
> Tin Ox 5
> CuCo3 1
> Bentonite 3%
>
> Oxblood red this I have used with no problems
> Neph sye 42
> Custer 9
> kaolin 2
> silica 23
> colemanite 13
> whiting 11
> copper carb .75%
> tin ox 1
> bent 3%
>
> Petes copper red from Peter Pinnell can't do any better than this I would
> try this one first
> Custer 73
> Gerstly borate 10
> whiting 12
> flint 5
>
> tin ox 1
> copper carb .3%
>
> Val Cushing vampire red
> k-200 spar 26
> frit 3185 5
> whiting 16
> barium carb 12
> soda ash 5
> ball clay 4
> EPK 4
> flint 28
>
> copper carb .5%
> tin ox 3%
Ron Roy on mon 26 oct 98
This copper red glaze - cone 10 - should never be used on anything that
might be used for food. It's short of silica and way oversupplied with
Barium. It will leach barium ions into food - a lot and in a relatively
short time - just so ya'll know.
It will craze and in so doing the acid attack will happen on even more of
the surface. It is not a durable glaze and barium is toxic.
Would it be a stable glaze at cone 6 - No!
There is no reason the use barium in copper reds to begin with.
RR.
>Lewis Red
>Cornwall 30
>BaCo3 49
>Silica 10
>Tin Ox 5
>CuCo3 1
>Bentonite 3%
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Donn Buchfinck on tue 27 oct 98
All the glazes I posted are c10 glazes
and copper reds do not need a heavy reduction
body reduction at c012 then light reduction to 10
do not drop out of the reduction
a heavy reduction burns the copper out
I dip with these glazes, a medium application is needed, unless you are good
with a sprayer
the tendency is to not get the glaze on thick enough
make some test tiles up
make them large 2 inches wide and 5 to 6 inches tall
the larger tiles will show the results better
dip all the way down to a count of 5 then half the tile for a count of 5
do a two dip test on the tile and I bet the are that is dipped twice will look
better
Donn Buchfinck
Do not skimp on the materials
> and put the glaze on a good quality porcelain body or slip
>
> Lewis Red
> Cornwall 30
> BaCo3 49
> Silica 10
> Tin Ox 5
> CuCo3 1
> Bentonite 3%
>
> Oxblood red this I have used with no problems
> Neph sye 42
> Custer 9
> kaolin 2
> silica 23
> colemanite 13
> whiting 11
> copper carb .75%
> tin ox 1
> bent 3%
>
> Petes copper red from Peter Pinnell can't do any better than this I would
> try this one first
> Custer 73
> Gerstly borate 10
> whiting 12
> flint 5
>
> tin ox 1
> copper carb .3%
>
> Val Cushing vampire red
> k-200 spar 26
> frit 3185 5
> whiting 16
> barium carb 12
> soda ash 5
> ball clay 4
> EPK 4
> flint 28
>
> copper carb .5%
> tin ox 3%
Chess Denman on tue 27 oct 98
I'd agree that tin is capricious in bringing out copper reds in my hands it
can do beautifull things or produce a mossy effect. I found my best results
came from adapting celadon glazes by reducing the iron and adding copper.
Also I have a little personal rule that the less copper the better the red
(obviously this can't be true in the extreme but it does seem true that
0.25% is better than 0.5.) I also find that a little zink oxide helps.
For what it's worth
I fire a propane kiln starting reduction at 1000C rather fiercely (judged by
a bigish flame at the peeps but not one coming out the burner ports) and
then decrease the reduction as I fire up to 1270 to a nutral draw at the
peep and soak there for an hour.
I suspect I am firing a little high though.
Happy to send you recipies if you want them.
Chess Denman
-----Original Message-----
From: Jeff Lawrence
To: CLAYART@LSV.UKY.EDU
Date: 26 October 1998 14:09
Subject: Re: Copper Reds/solve this problem
----------------------------Original message----------------------------
Donn Buchfink wrote:
>first I think before anyone starts to post a problem they should send a
copy
>of the recipe along
>
>second I think people should look at their glazes, and if there is not tin
>oxide in the glaze or one has substituted zircopax or some variation of it,
>this will cause problems
>
>it has been my limited experience that copper reds have to have tin oxide
in
>them to work
>I think it is also time for people to look at what/how they are firing
their
>kiln, and the application of the glaze to the ware, sometimes people apply
it
>too thin on the pots
>a simple rundown on the firing schedual would help, when do you do body
>reduction, do you reduce all the way through, oxidize in the end, reduce
hard
>in the end?? These are important cosiderations when trying to get the
glaze
>to work
>
>looking under a microscope is great but I think we have to solve the
problems
>so we can have money in the bank
Donn,
I think you're missing the point of this thread, which is to take a fresh
approach to the problem of reliable beautiful copper reds as taken by a very
gifted scientist. Money in the bank doesn't have anything to do with it as
far as I can see -- rather consider that same pursuit of the beautiful
you've claimed as your artistic raison d'etre. Ray is just fascinated by the
problem and I am fascinated by what he comes up with. Joy of learning, that
kind of thing.
Including all previous posts to a thread is a waste of bandwidth, inmho.
Sorry you missed the beginning. When I'm at a breaking point, hopefully
resting on roseate laurels, I'll post a full report.
Until then, FYI I'm firing to ^6, taking an hour and a half or so between
900-1000F, starting a medium level of reduction at 1100 (.5-.65 on my
Oxyprobe) and maintaining it to temperature (2245F on my pyrometer), 1/2
hour soak in reduction followed by 20 minutes soak oxidation (per Tichane's
suggestion). This was today's schedule.
As has been said, recipes travel poorly. In my experience they are always
particularly disgruntled when forced to visit my neck of the woods. Read
TOny Hansen's sermons against "trafficking in glazes" to help you cast away
those paper crutches. Contrary to your tin experience, the best reds I've
gotten to date had no tin. Any theories?
Jeff
J. D. Walker on wed 28 oct 98
Chess,
Please do share your red glaze. I am always looking for another one to
experiment with
jeff
where the sun is out in the mid west, but the pots are all still wet
Donn Buchfinck on thu 29 oct 98
thanks I have enough recipies for copper reds
I think the zink and copper and tin works great
for a celedon I use 7% barnard slip clay, it is sometimes called blackbird
and then I PUT IN 1% tin ox
plus I substitute grolleg china clay for the kaolin and I get a great blue
celedon
plus the 1% tin makes a copper based slip that is put on the clay body flash
red
if you want a great green celedon use 6 tile koalin then you get a green
Donn Buchfinck
hal mc whinnie on thu 29 oct 98
there is an excellent paper by pete pinnell in the current issue of
claytimes on the subject of how to fire copper reds.
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