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copper reds and strike firing/satin brown???

updated thu 15 nov 01


Joyce Lee on wed 14 nov 01

David H. said:
"I am amazed that people are getting reds that change color
after removal from the kiln. NEVER seen anything like that."
Curiosity has been pumping through my ancient being ever since we began =
receiving corroborating anecdotal info that OTHER claybuds...... =
experienced, production potters of long duration ...... have also seen =
the change of reds AFTER cooling ..... sometimes long after cooling. I =
trusted my observations but first figured it was best to just hush about =
anything so technical. We all know that that's not too likely to =
happen.... the hushing, that is. BUT, keep in mind, please, that I NEVER =
hazarded even a guess as to the cause of the changes. Way out of my =

For me, though, the purple I'm using fired to cones 10 or 11 also adds =
depth of color after reaching lowest temps of cooling ... in at least =
two cases, it went from creamy gray to large areas of progressively =
DEEPer purple below 700 F, adding even more splotches of purple when =
completely cooled and removed from the kiln. This is Coleman's Copper =
Purple. ????????? (My red has been Pinnell's Red..)

For now I'm aborting any further trips down the chemistry lane ..... I =
think I've ruined a few pieces (not red or purple) by opening and =
closing the kiln erratically ...... and I'm interfering with my firing =
schedule, which IS serious. At the same time that my reds and purples =
are deepening, I think it's the opening&closing activity (whoops! now =
THAT'S a guess as to cause ... sorry) that's turning some of my other =
glazes to dark brown .... a satin, smooth brown, true, (even Hank's Red =
Shino!) much like what I imagine the old legendary Albany Slip glazes =
must have produced. These suddenly-brown glazes are on iron-rich =
claybodies, but heretofore have been gorgeous shinos ..... Mel's and =
Hank's .... on the same claybody fired to the same temps as before.... =
and Midnight Blue, which I've fired many times on brown clay with =
mottled blues and tans as a result, is the same please-touch-me brown as =
the shinos .... only overt change is the swinging door. ?????

I might try a refire and keep the door shut except that I do like the =
brown ... plain ol' rich, satin, pattable, seductive, smooth brown.....

If any of you ChemBrains discover further evidence as to why these =
color changes occur, I'd appreciate hearing about it .... whether I =
fully comprehend or not.

Thanks for sharing and keeping me from feeling like Dorko of the Yearo.

In the Mojave headin' south on 14 again within minutes .... 3rd trip in =
three days....=20
thought I was going to have to drive the pickup, who only trucks over to =
the dump these days..... I need a new truck ..... too much for a holiday =
gift .... besides, I want boulders for my birthday this year ....... or =
some of those shelves that the Mayor bought if I can find them out here =
in the Liver Land ........ can't all be the Heart Land, right?
The rest of us have to choose our own organ..... shush now, Tony......