ELIZABETH JACOBS on sun 25 apr 99
A Question about Raku Firing...
I have taken a few workshops, read Steve Branfman's book, and have
tried different firing and post firing scenarios to do white crackle.
Some people fire crackle separately from coppers, and then some put both
copper and crackle on the same piece.
My question is, what are my choices? If I am firing a mixed load of
crackle with copper matte, am I over firing /under firing the coppers by
using the crackle as an indicator? Does any one have any suggestions of
visual clues to watch for when firing copper matte glazes? or do these
glazes tend to mature at the same temperature?
I am having trouble finding info on how to treat these very
different types of glazes. In all the workshops I've taken, the crackle
is treated differently by each instructor, in the firing as well as in
the post firing.
I have been getting decent results, but would appreciative any
insight, suggestions, etc...
Thank you, Thank you, Thank you,
Elizabeth
(out of the cast, into the splint)
************************************************************
E-MAIL: theclaystudio@home.com
VISIT MY WEB SITE AT
http://www.members.home.net/finearts/eliz.htm
*************************************************************
Marcia Selsor on mon 26 apr 99
We fire with a pyrometer to 1850 degrees F. The dry copper matts don't show
the maturity "by eye" because they're matt. Crackle whites vary with the many
formulas available. Try several; 'til you find one that works with your situatio
Marcia in Montana
ELIZABETH JACOBS wrote:
>
> ----------------------------Original message----------------------------
> A Question about Raku Firing...
> I have taken a few workshops, read Steve Branfman's book, and have
> tried different firing and post firing scenarios to do white crackle.
> Some people fire crackle separately from coppers, and then some put both
> copper and crackle on the same piece.
> My question is, what are my choices? If I am firing a mixed load of
> crackle with copper matte, am I over firing /under firing the coppers by
> using the crackle as an indicator? Does any one have any suggestions of
> visual clues to watch for when firing copper matte glazes? or do these
> glazes tend to mature at the same temperature?
> I am having trouble finding info on how to treat these very
> different types of glazes. In all the workshops I've taken, the crackle
> is treated differently by each instructor, in the firing as well as in
> the post firing.
> I have been getting decent results, but would appreciative any
> insight, suggestions, etc...
> Thank you, Thank you, Thank you,
> Elizabeth
> (out of the cast, into the splint)
>
> ************************************************************
>
> E-MAIL: theclaystudio@home.com
>
> VISIT MY WEB SITE AT
>
> http://www.members.home.net/finearts/eliz.htm
>
> *************************************************************
--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/spain99.html
Morgan Britt on mon 26 apr 99
I just finished a raku workshop at Sierra Nevada College with Rodney Mott
(great workshop - super high energy) and had amazingly consistent results.
(Unless they key was the altitude - so what - I'll drive the two hours to
Lake Tahoe for results like this). We fired both crackles and coppers in the
same load. When mature (shiny), the coppers were pulled first and put
immediately in the can, flashed once after about 3 minutes, left in the can
for about 15-20, and sprayed with the hose when the color was right. The
crackles we pulled last and set out on a brick until pinging began. Then
they were blown on lightly - the key is gently and lightly, and only until
you heard the crackle once - the more blowing the smaller the crackle. Then
leave in the can as LONG as possible. Several pieces had large crackle with
deep black lines. In some cases the crackle averaged 1/2" clear areas -
absolutely exquisite. Another note is that the glaze was extremely thick
when applied. Be careful with very thin pieces as they tend to cool too
much. One piece was unbelievable - had a dry copper slip brushed here and
there over the clear crackle on white clay. On the back where the glaze
reduced in the kiln it had gorgeous reds, blues, greens, (glossy, not raku
metallic) with shot of bright copper here and there. I can't wait to get my
web site up and show this one off. Good luck! If you try it, I'd like to
know how it worked for you.
Morgan
ELIZABETH JACOBS wrote:
> ----------------------------Original message----------------------------
> A Question about Raku Firing...
> I have taken a few workshops, read Steve Branfman's book, and have
> tried different firing and post firing scenarios to do white crackle.
> Some people fire crackle separately from coppers, and then some put both
> copper and crackle on the same piece.
> My question is, what are my choices? If I am firing a mixed load of
> crackle with copper matte, am I over firing /under firing the coppers by
> using the crackle as an indicator? Does any one have any suggestions of
> visual clues to watch for when firing copper matte glazes? or do these
> glazes tend to mature at the same temperature?
> I am having trouble finding info on how to treat these very
> different types of glazes. In all the workshops I've taken, the crackle
> is treated differently by each instructor, in the firing as well as in
> the post firing.
> I have been getting decent results, but would appreciative any
> insight, suggestions, etc...
> Thank you, Thank you, Thank you,
> Elizabeth
> (out of the cast, into the splint)
>
> ************************************************************
>
> E-MAIL: theclaystudio@home.com
>
> VISIT MY WEB SITE AT
>
> http://www.members.home.net/finearts/eliz.htm
>
> *************************************************************
--
Morgan Britt
morgan@unlimited.net
Terry Hagiwara on tue 27 apr 99
elizabeth,
anyway you like :) depending on what you want to achieve: that is my
suggetsion.
first of all, i assume you are preparing your own raku glaze, aren't you?
in my case, i use colemanite 800 + neph.sye. 200 as the base, then add
colorant,
for instance, ultrox 100 for crackled white, or copper carbonate 100 + red
iron oxide 50 for metallic red, etc.
as the result (of basing on the same base) they mature more or less at the
same temperature.
you can apply metallic red (copper) and crackle white on the same piece,
without any problem.
only thing you may be careful is about what you want to achieve design-wise.
you may not want them mix, then you need about 1/8-in.separation between
them (well, depending on the glaze thickness and shape of the piece).
metallic red tend to run more than white. but again, if they mix, the color
could be crimson red, if properly reduced, or clear nice copper green, if
not reduced well. just that the separation among the colors is not crisp.
when i want to get larger crackle size, i use colemanite 500 + neph.sye 500
+ ultrox 100, for crackle white. this matures at higher temperature. yet,
you can use both crackle white glazes on the same piece to see the varying
crackle sizes.
alligator glaze and other copper matt have slightly different base, yet i
use alligator, metallic red, and crackle white on the same piece, without
problem. (or, i didn't see the problem yet.)
if you really want to monitor the kiln temperature, you can use
witness-cone.
happy raku-ing!
terry hagiwara
terryh@pdq.net
www.geocities.com/SoHo/Cafe/3755
Susan Goldstein on tue 27 apr 99
In a message dated 4/26/99 9:45:19 AM Eastern Daylight Time, selsor@imt.net
writes:
<<
----------------------------Original message----------------------------
We fire with a pyrometer to 1850 degrees F. The dry copper matts don't show
the maturity "by eye" because they're matt. Crackle whites vary with the many
formulas available. Try several; 'til you find one that works with your
situatio
Marcia in Montana >>
Was curious about the temperature. I usually fire to 1850 but yesteday did
several loads at 1700 and saw absolutely no difference.
Susan
Anne Hunt on thu 29 apr 99
Hi, Elizabeth!
Am running way behind the power curve in responding to your post @ mixed
loads (and in just about everything else, as well)...being late this way
also let me see what others posted to the list before I responded; coddles
my insecurity about things clay, so maybe I don't step out there and say
something really dumb.
So, am gonna say something really dumb anyway. As I understand it,
over/underfiring a raku glaze doesn't have anything to do with whether the
glazes are crackle or in need of high reduction. They all require a certain
themp or cone to turn out.
If you have a mixed load of ^06 crackles and, say, copper matte and a
Higby Water Blue, they'll all perform according to spec.
I think the issue here is the amount of reduction required for the
various glazes. Didn't somebody like Tom Buck or Dewitt G., or another raku
guru answer you by private post?
At any rate, I PREFER mixing loads, 'cause I work alone ( somebody's
gonna jump on that): turn of the burner, get the kiln lid off, pull, jam in
can, feed paper, lid ---you know the drill. If I have one LARGE piece and
two smaller ones, or four smaller pieces (whatever), odds are that I'm going
to end up with 1 to 2 pieces oxidized way more than I want them to be
unless I'm using the Higby, then it turns our cool either way ---it's
ambidextrous that way).
But, if I have a mixed load, the "crackles" sit in the kiln happily
until I'm though thrashing around with the high-reduction pieces --- with no
harm done, as far as I know. Someone may say that I'm losing some
crackling by nullifying some of the thermal shock value, but I haven't heard
it yet.
There is a trade-off, however, if you have a crackle and a
high-reduction/copper/flashing-type glaze on the same piece. As I've seen
and experienced it, if you treat the piece as if it's a crackle -- and blow
on it, burp it, etc., then your'e going to lose the brilliance, copper
colors and flashing in the other glaze. Conversely, if you highly reduce
the piece, you'll get the white, but very little crackling. And that's o.k.
if you're willing to make those trade-offs.
I'm horrible with names, but there's a fellow in Seattle named Greg
Bailey (???) who makes platters, mirror frames, vases, etc. with a
predominantly Pacific Northwest Native American motif. They're gorgeous,
despite the abovementioned trade-off; so some interesting things can
happen.
Hope that helped...
It's sunshiney in sequim, and I've "ops-checked" Pale Lemon Lustre and Pac
Man on top of Dragonfly (Dragon Man? Nanoo-nanoo!)
anne & kitties
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