Tom Buck on mon 30 aug 04
mel jacobson, john britt, and others, have started a thread that deals
with the glaze recipe and whether the materials list is in itself
sufficient to allow a reproduction elsewhere from its origin.
John Britt's elegant oilspot glaze (I have a sample pot) is the
end-product of extensive study and testing. I'd love to copy it but know
ahead of time that it will be hard and perhaps unlikely that I will
succeed. I do not have his claybody to hand, I do not have his Cone 10
fossil-fueled kiln here as well. and should I mix his glaze recipe, and
try it in a local C10 kiln, I strongly suspect I will not be able to match
his result without many tests, and even that is not a road to success.
To make another stress on the fact that the "recipe" is not a
guarantee of success, please examine V. Scotchie's "Bronze Metallic" - a
glaze that allows her to achieve unusual and sometimes startling pieces.
Here is the Cone 6 Oxidation materials list:
Bronze Metallic Cone 6 Ox.
60 Redart
5 OM#4 ballclay
5 Flint/silica/quartz
45 Manganese dioxide
5 Copper carbonate (basic)
5 Cobalt carbonate (basic)
10 Gerstely borate (or equal)
Anyone trying this for the first time will be easily disappointed, unless
you get the nitty-gritty from Virginia herself. A partial clue to success
may be noted from the Cone 05 version in her manual "V.Scotchie Bronze
Glaze for bisqueware Cone 05 (assume oxidation)"
60 Sinter (? a frit? or prefired feldspar?)
30 Manganese dioxide
9 copper oxide (assume black oxide)
1 CMC (carboxy methyl cellulose)
and added at the bottom of the list: "Apply 1-5 layers".
With this added bit of data, the matt black surface I had earlier
encountered became metallic bronze using the Cone 6 Ox recipe above. Yet,
it only went metallic at a full Cone 6, much less that that and the
metallic look did not appear on my white-burning procellaineous stoneware.
one final item: Val Cushing's "Weird Matt" Cone 4+ Oxidation (see
archives), looks crummy on a buff/tan stoneware, yet achieves what Val C
was seeking on a white-burning body.
In summary, the glaze materials list is strictly a guide, a
starting point, for the individual potter to explore.
good pots. peace Tom B.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
Antoinette Badenhorst on tue 31 aug 04
Thanks Tom. You are underlining what I just told my students this past
week. They started some glaze tests this week under my "supervision"
Regards.
Antoinette Badenhorst
105 Westwood Circle
Saltillo MS
38866
662 869 1651
www.clayandcanvas.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Tom Buck
Sent: Monday, August 30, 2004 10:36 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: The "Recipe"
mel jacobson, john britt, and others, have started a thread that deals
with the glaze recipe and whether the materials list is in itself
sufficient to allow a reproduction elsewhere from its origin.
John Britt's elegant oilspot glaze (I have a sample pot) is the
end-product of extensive study and testing. I'd love to copy it but know
ahead of time that it will be hard and perhaps unlikely that I will
succeed. I do not have his claybody to hand, I do not have his Cone 10
fossil-fueled kiln here as well. and should I mix his glaze recipe, and
try it in a local C10 kiln, I strongly suspect I will not be able to
match
his result without many tests, and even that is not a road to success.
To make another stress on the fact that the "recipe" is not a
guarantee of success, please examine V. Scotchie's "Bronze Metallic" - a
glaze that allows her to achieve unusual and sometimes startling pieces.
Here is the Cone 6 Oxidation materials list:
Bronze Metallic Cone 6 Ox.
60 Redart
5 OM#4 ballclay
5 Flint/silica/quartz
45 Manganese dioxide
5 Copper carbonate (basic)
5 Cobalt carbonate (basic)
10 Gerstely borate (or equal)
Anyone trying this for the first time will be easily disappointed,
unless
you get the nitty-gritty from Virginia herself. A partial clue to
success
may be noted from the Cone 05 version in her manual "V.Scotchie Bronze
Glaze for bisqueware Cone 05 (assume oxidation)"
60 Sinter (? a frit? or prefired feldspar?)
30 Manganese dioxide
9 copper oxide (assume black oxide)
1 CMC (carboxy methyl cellulose)
and added at the bottom of the list: "Apply 1-5 layers".
With this added bit of data, the matt black surface I had
earlier
encountered became metallic bronze using the Cone 6 Ox recipe above.
Yet,
it only went metallic at a full Cone 6, much less that that and the
metallic look did not appear on my white-burning procellaineous
stoneware.
one final item: Val Cushing's "Weird Matt" Cone 4+ Oxidation
(see
archives), looks crummy on a buff/tan stoneware, yet achieves what Val C
was seeking on a white-burning body.
In summary, the glaze materials list is strictly a guide, a
starting point, for the individual potter to explore.
good pots. peace Tom B.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
________________________________________________________________________
______
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David Hewitt on wed 1 sep 04
In message , Tom Buck writes
>mel jacobson, john britt, and others, have started a thread that deals
>with the glaze recipe and whether the materials list is in itself
>sufficient to allow a reproduction elsewhere from its origin.
>
> John Britt's elegant oilspot glaze (I have a sample pot) is the
>end-product of extensive study and testing. I'd love to copy it but know
>ahead of time that it will be hard and perhaps unlikely that I will
>succeed. I do not have his claybody to hand, I do not have his Cone 10
>fossil-fueled kiln here as well. and should I mix his glaze recipe, and
>try it in a local C10 kiln, I strongly suspect I will not be able to match
>his result without many tests, and even that is not a road to success.
I agree with every word that Tom has said, particularly with regard to
such glazes as oil spot. I have just emptied my kiln, which was filled
with oil spot bowls and they are all good by my standards. As I think
you know, I have been producing oil spot for many years now (see my web
site for an example) and have willingly offered the recipe to anyone who
wants it. However I suspect that few who have enquired have been able to
reproduce the same results as I seem to get on a regular basis. If I am
wrong in this I would like to hear from them.
Fortunately not all glazes are so tricky to reproduce, but if you want
to try and use others recipes you certainly want to get as much detail
as possible from the originator. Both a recipe with analysis based on
the originator's raw material data and the clay body used is a necessary
start, but you need much more on the application of the glaze and the
firing regime.
For what it is worth I have tried to express my thoughts on
'Transporting Glazes' with an article under that name on my web site.
This may well not be complete enough, but it is a start.
David
>
> To make another stress on the fact that the "recipe" is not a
>guarantee of success, please examine V. Scotchie's "Bronze Metallic" - a
>glaze that allows her to achieve unusual and sometimes startling pieces.
>Here is the Cone 6 Oxidation materials list:
> Bronze Metallic Cone 6 Ox.
> 60 Redart
> 5 OM#4 ballclay
> 5 Flint/silica/quartz
> 45 Manganese dioxide
> 5 Copper carbonate (basic)
> 5 Cobalt carbonate (basic)
> 10 Gerstely borate (or equal)
>
>Anyone trying this for the first time will be easily disappointed, unless
>you get the nitty-gritty from Virginia herself. A partial clue to success
>may be noted from the Cone 05 version in her manual "V.Scotchie Bronze
>Glaze for bisqueware Cone 05 (assume oxidation)"
> 60 Sinter (? a frit? or prefired feldspar?)
> 30 Manganese dioxide
> 9 copper oxide (assume black oxide)
> 1 CMC (carboxy methyl cellulose)
>and added at the bottom of the list: "Apply 1-5 layers".
> With this added bit of data, the matt black surface I had earlier
>encountered became metallic bronze using the Cone 6 Ox recipe above. Yet,
>it only went metallic at a full Cone 6, much less that that and the
>metallic look did not appear on my white-burning procellaineous stoneware.
>
> one final item: Val Cushing's "Weird Matt" Cone 4+ Oxidation (see
>archives), looks crummy on a buff/tan stoneware, yet achieves what Val C
>was seeking on a white-burning body.
> In summary, the glaze materials list is strictly a guide, a
>starting point, for the individual potter to explore.
> good pots. peace Tom B.
>
> Tom Buck ) -- primary address.
> "alias" or secondary address.
> tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
>mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
--
David Hewitt
Web:- http://www.dhpot.demon.co.uk
Ivor and Olive Lewis on wed 1 sep 04
Dear Tom Buck,
Is it possible to believe this recipe is a "glaze"?
> 60 Redart
> 5 OM#4 ballclay
> 5 Flint/silica/quartz
> 45 Manganese dioxide
> 5 Copper carbonate (basic)
> 5 Cobalt carbonate (basic)
> 10 Gerstely borate (or equal)
There is scarcely enough melting agent in it to hold the stuff
together and stick it to the pot. It is half pure poison as well.
Best regards.
Ivor Lewis.
Redhill,
S. Australia.
Ron Roy on fri 3 sep 04
Hi Ivor,
I would not call it a glaze - you are right - with Al2O3 at 1.05 and SiO2
at 7.41it would not melt very well even at cone 10. Obviously concocted
before we were aware of the toxic consequences of breathing Manganese dust
and fumes.
If it's fired in reduction - putting the Fe2O3 into unity - then the Al2O3
is 0.84 and the SiO2 is 5.91 - still high for even cone 10.
Better to call it an underglaze and hold your breath when using and firing it.
Scary stuff - I would advise against it's use.
RR
>Is it possible to believe this recipe is a "glaze"?
>> 60 Redart
>> 5 OM#4 ballclay
>> 5 Flint/silica/quartz
>> 45 Manganese dioxide
>> 5 Copper carbonate (basic)
>> 5 Cobalt carbonate (basic)
>> 10 Gerstely borate (or equal)
>There is scarcely enough melting agent in it to hold the stuff
>together and stick it to the pot. It is half pure poison as well.
>Best regards.
>Ivor Lewis.
>Redhill,
>S. Australia.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ivor and Olive Lewis on sat 4 sep 04
Dear Ron,
Thanks for your support on that one. I did not put the recipe through
the number cruncher. Just a quick inspection gave me a good enough
picture.
Enjoy your weekend.
Best regards,
Ivor.
Ivor Lewis.
Redhill,
S. Australia.
Tom Buck on sun 5 sep 04
Ivor Lewis, Ron Roy, et al:
Greetings -
if you convert the Scotchie bronze recipe to Seger form, using the
conventional flux oxides totalling ONE, then yes the resulting numbers
suggest this mix is way beyond Cone 6 oxidation melting.
But things in chemistry are not always what they seem. A major
ingredient in the mix is Manganese Dioxide, MnO2, and as such is most
unlikely to be a flux oxide because the standard Flux Oxides are compounds
with a metallic valence of 1 or 2, not 4. However, MnO2 soon becomes MnO
(at 535 oC) and Mn++O-- will act as a flux oxide, and this oxide in combo
with Cu++ and Co++ oxides will bring about an excellent melting of the mix
at C6. The glaze, if thick enough, forms a hard, high gloss surface
distinctly bronze in hue.
will the glaze surface change under normal atmospheric
conditions?....not at all likely, since V Scotchie's artpieces have been
around for quite some time with no degradation. my tests pieces are
the same after a few years.
will it resist acid attack? unknown, not tested because the glaze
is not used on functional ware.
but it was needful for Ron and Ivor to note that this mix is not
suitable for food pots.
as for firing, not a health problem with today's well vented
electric kilns, unless you have neighbours who may think you are harming
them when you fire your kiln.
til later. . peace Tom
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
Snail Scott on mon 6 sep 04
At 03:31 PM 9/5/2004 -0400, you wrote:
>...The glaze, if thick enough, forms a hard, high gloss surface
>distinctly bronze in hue...
>...will the glaze surface change under normal atmospheric
>conditions?....not at all likely...
I've used a similar recipe. There are a lot of
them out there, and they're not fussy about
variations in proportion, or about firing range.
'Mine' was cribbed from someone who cribbed it
from someone else, who cribbed it from Jun Kaneko.
I've made work covered with this glaze type which
has been outside in the sun and snow for over ten
years with no visible changes. I wouldn't eat off
it, or hang around the kiln during firings, but
it's been a durable and reliable glaze for my
sculptural work.
-Snail Scott
Ron Roy on mon 6 sep 04
Hi Tom,
You are right - I was unsure of the role of MnO2 and did not include it as
a flux for cone 6 - which it is.
Hamer says it converts to MnO at 1080C by the way - below that temperature
it is an anti flux.
I don't think there are as many well ventillated kilns in use as you thnk
there are. I would certainly insist that the warning come with the recipe
in this case.
I understand that ingestion of Manganese is not a problem - it is the dust
and fumes that we have to avoid. I do not know what orange juice would
taste like being against it for 5 minutes - care to do the experiment Tom?
Thanks again for catching my error - it is one of the best parts of ClayArt
- sieving out the errors and misinformation.
RR
> if you convert the Scotchie bronze recipe to Seger form, using the
>conventional flux oxides totalling ONE, then yes the resulting numbers
>suggest this mix is way beyond Cone 6 oxidation melting.
>
> But things in chemistry are not always what they seem. A major
>ingredient in the mix is Manganese Dioxide, MnO2, and as such is most
>unlikely to be a flux oxide because the standard Flux Oxides are compounds
>with a metallic valence of 1 or 2, not 4. However, MnO2 soon becomes MnO
>(at 535 oC) and Mn++O-- will act as a flux oxide, and this oxide in combo
>with Cu++ and Co++ oxides will bring about an excellent melting of the mix
>at C6. The glaze, if thick enough, forms a hard, high gloss surface
>distinctly bronze in hue.
>
> will the glaze surface change under normal atmospheric
>conditions?....not at all likely, since V Scotchie's artpieces have been
>around for quite some time with no degradation. my tests pieces are
>the same after a few years.
> will it resist acid attack? unknown, not tested because the glaze
>is not used on functional ware.
> but it was needful for Ron and Ivor to note that this mix is not
>suitable for food pots.
> as for firing, not a health problem with today's well vented
>electric kilns, unless you have neighbours who may think you are harming
>them when you fire your kiln.
>
> til later. . peace Tom
>
>Tom Buck ) -- primary address.
>"alias" or secondary address.
> tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
>mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ivor and Olive Lewis on mon 6 sep 04
Dear Tom,
I appreciate your view of the chemistry of this rather weird mixture
of ingredients but I am not sure that it is going to be a vitreous
substance even if Manganese oxides and Copper oxides melt by the time
cone six is attained.
I suspect that the result will be a conglomerate of some description
with those items that do not melt being bound in place with those that
do.
I recall that there is just not enough Silica there to make a molten
vitreous phase possible.
Just done a check, MnO melts at 1840=BA C. Mn2O7 explodes at 95=BA. MnO2
and, as you said Mn2O3 decompose,
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
.
Snail Scott on tue 7 sep 04
At 04:53 PM 9/6/2004 +0930, Ivor wrote:
>I suspect that the result will be a conglomerate of some description
>with those items that do not melt being bound in place with those that
>do.
>I recall that there is just not enough Silica there to make a molten
>vitreous phase possible...
I can't speak to your 'stuff in suspension'
theory, but the resulting substance is visibly
quite melted. Since the resulting color is
thickness-sensitive, it clearly shows rivulets
of thicker (gold) drips amongst thinner (grey)
areas if applied to the right thickness. It also
develops a 'crinkly' skin on thick areas in
certain conditions. (Slow cooling, I think, but
haven't really tested to confirm). It's also
reduction-sensitive, with high levels of reduction
tending to result in a less-gold, more-grey
effect (sort of the reverse of the usual
reduction effect.)
This glaze violates all the rules of formulation.
But, the result is apparently melted (or at
least in solution) and reasonably stable. Whether
this is truly 'vitreous' or 'something else', is
perhaps the question. So, if it's not vitreous,
what would we call such a melt?
-Snail
John Hesselberth on tue 7 sep 04
Hi Snail,
I call them surface treatments.
Regards,
John
On Tuesday, September 7, 2004, at 08:07 AM, Snail Scott wrote:
> So, if it's not vitreous,
> what would we call such a melt?
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
Ivor and Olive Lewis on wed 8 sep 04
Dear Snail,
I do not recall saying the material would not melt. My intention was
to cast doubt on the assumption that such a collection of materials
would become fully molten, as might well be expected from a recipe
compounded to more usual style of Unity formulae. It seemed to me that
the recipe was short in substances that would promote melting and
fusion in the sense that a glass phase would be present.
I was thinking more in terms of Cementation when I suggested that
recipe might be structured like a conglomerate material once it was
fired. So, like concrete some materials remain as discreet fragments
while others do become a sort of liquid glue that binds all together
and to the ceramic of the pot.
I suppose in a sense it might be an "engobe"
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
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