Llewellyn Kouba on mon 30 sep 02
Readers,
This past week I finally got the first copper reds in my glaze kiln. This
all happened through the kindness of Tama Smith of Prairie Fire Pottery in
Beach ND who coached me through a firing. I realized that Tama cranked up
the heat a lot (harder) faster and may have reduced earlier. I was pleased
with the reds and actually got reds in many places in my kiln. Tama wasn't
able to stay for the unloading to see the results but she questioned
whether I had in fact ever had a reduction fire? This still puzzles me.
Her conjecture was that I have been oxidizing all along? I have seen the
reduction flame at the top of my port and licking at the bottom. Under
Tama's fire log we had good reduction at the top spie and very good on the
bottom. I did notice too that the kiln furniture (stilts) have a more
golden brown deeper tone after her firing. I thought I had heard something
long ago that you can tell if a person had reduction just by looking at the
kiln stilts? I don't know if this is true but in any case I am more
puzzled now if I have been doing largely oxidation firings and didn't know
it or what? I have always been more than pleased with my kiln results
except I had never gotten a copper red until now. I really believe I have
had reduction firings but that Tama has a much faster flame and therefore a
hotter fire. We took the kiln to cone 9 range the same as I also fire
to. Some of the other glazes in the kiln were not as favorable to me
aesthetically but all in all I am pleased now that if I want to get copper
reds I am sure I can do so. It was a good and growth full experience and
one that I am glad I did. We fired all night and had a blast of a good
time. Thank you Tama, and student Carol. Pictures forthcoming.
Llewellyn Kouba
John Weber on tue 1 oct 02
Well, I will take this opportunity to say that now that I have my Oxyprobe,
fired it once so I don't know much yet, but what I do know it that it tells
me when I'm in reduction. The days of my looking at the flame screaming out
the peep hole to decide if I was in reduction are over. I strongly suggest
that you try to attend a firing done by someone with an Oxyprobe so you can
witness the flame, the atmosphere, the feel of moderate or heavy reduction
when it is efficient. Better yet, get someone who has an Oxyprobe to come
over and use it on your kiln. Sorry for my new enthusiasm for this
instrument but it really did open my eyes. Good luck.
Dan Dermer on wed 2 oct 02
I agree that an oxygen probe is a *huge* help in getting good, even copper
reds -- something I've been trying to do. But, the Oxygen probe isn't
everything. I've had one for a year now, about as long as I've had my gas
kiln. I'm only just starting to get really even copper reds from my last
few firings. Clayart members have been amazing in sharing tips on getting
copper reds to work. I'll share my experience:
Initially I tried to follow the schedule of reduction beginning at cone 010,
and maintaining medium reduction (.55-.7) through the end of the firing --
easing into oxidation only at the very end. In my kiln (an updraft), that
was a challenge without having the top finish at Cone 7-8 and the bottom at
Cone 10. (read on for how that was solved...) AND, some firings would give
reasonably good copper reds -- others all splotchy -- just when I thought I
knew what I was doing with the firing down procedure, etc.
In addition to the firing schedule (when to reduce, when to oxidize, when to
re-light again on the way down), I think the following has helped my copper
reds:
1) good turbulence; in the last few firings in my kiln, I switched to a
faster schedule on the way up, in part so I wouldn't be so sleepy when it
came time for the 'firing down' procedure. Higher pressure was also the
recommended cure from my kiln vendor for bringing more heat to the top. I
now use 4.5"-5" pressure (instead of 3.5") from the time I start reducing
all the way to cone 10; I open my damper proportionally further to keep
reduction at .55-.7 on the Oxy Probe, lighter as the firing proceeds.
The increased pressure gives increased turbulence and more even reduction
throughout -- not to mention more steady readings on the Oxy Probe. When the
bottom of my kiln reaches cone 10 and the top is still at c9 barely bending,
I switch to an oxidation/neutral atmosphere (to pull heat to the top) until
cone 10 is at 3 o'clock on top -- usually takes 30-45 minutes. I then
reduce pressure to 3.5" and soak in oxidation for another 10 minutes, to
compensate for the shorter firing time to c10.
2) layering/spraying glazes; based on a tip from Jonathan Kaplan (clayart
archives), I now dip the first coat of copper red glaze, and spray a second
coat of another copper red glaze. I'm no expert, but I believe that using
two glazes with slightly different types of fluxes 'seals in' the red
better. :-) Since the second glaze I'm using has a iron oxide in it (and
the first glaze doesn't), it's very easy to spray one over the other and see
when you have it covered evenly. I no longer believe that you have to glaze
the piece thickly bordering on absurd for good copper reds. One good quick
dip, followed by another dip in another glaze, works fine for me. I spray
the second glaze on to make sure that it's applied evenly, tho.
Anyhow, I have some pictures of Copper Red pots from my last two firings
here:
http://pages.sbcglobal.net/ddermer
I'm excited about them! Of course, who knows how the next ones will come
out?? I just updated my site, so check it out if you like.
(Still working out the bugs there too...)
-Dan
Chris Morgan on tue 4 mar 03
First post as well....
Just got my first batch of copper reds out of the kiln the other day. I
had no problems getting a dark red (more of a burgandy actually) or
with consistancy (everything came out pretty much the same except for
one bright green piece). What I do have have a problem with is gloss
and flow, which leads me to sespect I was simply under fireing. I
fired to cone 6. The galze has a somewhat leathery gloss, and the
glaze did not flow at all. The formula I usedwas modified from
Tichanes glaze in Copper Red Glazes by substituting frit #3195 for frit
#25 as #25 was not available.
Custer Feldspar 39
Pulverized Flint 23
Limestone 15
Frit #3195 21
Copper Carboonate 1
Tin Oxide 2
The kiln was fired to cone six in reduction from 700 degrees farenheit
up to cone six. Firing higher may not be an option as I share the kiln
wih others in a classroom environment and the instructor fires the kiln,
although I highly suspect that is what I need to do. Any advise for
lightning up the red or helping with gloss and flow would be great.
Thanks!
Chris Morgan
Freelance Ceramist
Illinois College
Jacksonville IL
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