Alisha Clarke on tue 31 jul 07
I just tested out Jamie's "REAL Blue" revision of Ron and John's
Waterfall Brown (subbing 4% Copper Carb and .5% Cobalt Carb for the
coloring oxides) in my last kiln load. As Jamie said, this is really
blue, but it also seamed to foam up at the point where it melted down
the pot, leaving a foam line either at the bottom of the pot (where
only the WF Blue was used) or at the bottom of the WF Blue that was
layered over other glazes (including Bright Sky Blue, WF Brown and
Raspberry). The WF Brown that I fired in the same load did not have
this problem.
Is there any idea of why these coloring oxides resulted in the foaming
with the same glaze. I'm quite sure the base was mixed correctly, but
there's always the slight possibility that I made a measuring error
(but I doubt it -- I tend to be very anal about the measurements).
Alisha
On 6/30/07, Jamie Yocono wrote:
> Arthur,
>
> Almost all of my Waterfall experiments use the same 4 base ingredients, at
> the same percentages in the book. Only the white version's base was tweaked
> a little.
>
> I have two blues- one I call J/R's Blue, for I wouldn't have found it
> without the author's book. The other is called REAL blue because it jumps
> right out at you. It's almost TOO blue.
>
> For J/R's Blue - add 5% RIO and 1% Rutile
> For REAL Blue - add 4% Copper Carb and .5% Cobalt Carb
>
> Hope this helps!
>
> Jamie in Vegas
>
>
>
> <<>
> Your new waterfall colors are spectacular. I paticularly like the blues.
> Would you be willing to share the colorant variations that produced them?
>
> Arthur in Englewood>>>
>
> ______________________________________________________________________________
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--
~~~~~~~~~~~~~~~~~~~~~~~~~
Alisha Clarke
www.alishaclarke.com
John and Judy Hesselberth on wed 1 aug 07
On Jul 31, 2007, at 10:26 AM, Alisha Clarke wrote:
> Is there any idea of why these coloring oxides resulted in the foaming
> with the same glaze. I'm quite sure the base was mixed correctly, but
> there's always the slight possibility that I made a measuring error
> (but I doubt it -- I tend to be very anal about the measurements).
> Alisha
Hi Alisha,
Most all glazes go through some serious off-gassing during some part
of their firing cycle. I had the same results you did when I tried to
develop other color variants of the Waterfall Brown base. I suspect
that Jamie is having success because he is firing half a cone or
maybe a full cone lower than you or I did. Try lowering your firing
temperature to cone 5 (if it is currently a real cone 6) and see if
that helps.
Regards,
John
Alisha Clarke on thu 2 aug 07
Thanks John, that could be part of the issue for me. I use your firing
schedule (from the book), but I've tended to be on the hot side of ^6
(probably about 6.5). Some of these pots were also bisqued too high. I
just changed the thermocouple in my kiln after a couple of bisque
firings with ^04 flat. Could this have also contributed to the foaming
problem?
Alisha
On 8/1/07, John and Judy Hesselberth wrote:
> On Jul 31, 2007, at 10:26 AM, Alisha Clarke wrote:
>
> > Is there any idea of why these coloring oxides resulted in the foaming
> > with the same glaze. I'm quite sure the base was mixed correctly, but
> > there's always the slight possibility that I made a measuring error
> > (but I doubt it -- I tend to be very anal about the measurements).
> > Alisha
>
> Hi Alisha,
>
> Most all glazes go through some serious off-gassing during some part
> of their firing cycle. I had the same results you did when I tried to
> develop other color variants of the Waterfall Brown base. I suspect
> that Jamie is having success because he is firing half a cone or
> maybe a full cone lower than you or I did. Try lowering your firing
> temperature to cone 5 (if it is currently a real cone 6) and see if
> that helps.
>
> Regards,
>
> John
>
> ______________________________________________________________________________
> 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.
>
--
~~~~~~~~~~~~~~~~~~~~~~~~~
Alisha Clarke
www.alishaclarke.com
John and Judy Hesselberth on thu 2 aug 07
On Aug 2, 2007, at 10:19 AM, Alisha Clarke wrote:
> I
> just changed the thermocouple in my kiln after a couple of bisque
> firings with ^04 flat. Could this have also contributed to the foaming
> problem?
Hi Alisha,
I don't think too hot a bisque would have contributed to foaming or
blistering, but too hot a glaze firing certainly can. Waxwing Brown
is particularly sensitive to blistering if fired too hot. I speculate
that is caused by thermal reduction of some of the iron oxide which
gives off oxygen. Even though the literature says this doesn't occur
until cones 8-10 I think it sometimes occurs as low as cone 6 or 7.
What I said above causes me to think about firing Waxwing to Cone 8
and see if it turns into an oil spot. After all oil spot glazes are
caused by thermal reduction of iron oxide followed by a short period
to let the burst bubbles heal over. So many experiments to run, so
little time.
Regards,
John
Ron Roy on mon 6 aug 07
Hi Alisha,
How much cobalt did you use?
Cobalt is a flux at cone 6 so it may be the problem.
If you would like to try some variations (more refractory) of that glaze
let me know and tell me what colours you want to try.
RR
>Thanks John!
>
>That firing went to cone 6 touching, so it was definitely a bit hot.
>I'll try firing it a little lower.
>However, I didn't have the same problem with the standard Waterfall
>Brown in the same kiln load. Would the Cobalt have contributed to this
>somehow?
>
>Alisha
>
>
>On 8/2/07, John and Judy Hesselberth wrote:
>> On Aug 2, 2007, at 10:19 AM, Alisha Clarke wrote:
>>
>> > I
>> > just changed the thermocouple in my kiln after a couple of bisque
>> > firings with ^04 flat. Could this have also contributed to the foaming
>> > problem?
>>
>> Hi Alisha,
>>
>> I don't think too hot a bisque would have contributed to foaming or
>> blistering, but too hot a glaze firing certainly can. Waxwing Brown
>> is particularly sensitive to blistering if fired too hot. I speculate
>> that is caused by thermal reduction of some of the iron oxide which
>> gives off oxygen. Even though the literature says this doesn't occur
>> until cones 8-10 I think it sometimes occurs as low as cone 6 or 7.
>>
>> What I said above causes me to think about firing Waxwing to Cone 8
>> and see if it turns into an oil spot. After all oil spot glazes are
>> caused by thermal reduction of iron oxide followed by a short period
>> to let the burst bubbles heal over. So many experiments to run, so
>> little time.
>>
>> Regards,
>>
>> John
>>
>>
>>__________________________________________________________________________
>>____
>> 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.
>>
>
>
>--
>~~~~~~~~~~~~~~~~~~~~~~~~~
>Alisha Clarke
>www.alishaclarke.com
>
>______________________________________________________________________________
>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
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