gafergus on sun 27 oct 96
Hey you Raku experts:
Is there anyway to control the size of the crackle of a raku glaze? I am
using a clear raku glaze (Laguna) that does very good small crackle. I
have seen several works that exhibit large crackle and I would like to
try to acheive that. I've tried thicker and thinner glazing but it
doesn't seem to make any difference. Does it have to do with the way it
is reduced, or the clay body (I use Soldate 60)?
Any help would be appreciated!
Thank
Gary Ferguson
Jeff Lawrence on mon 28 oct 96
Gary Ferguson writes:
> Is there anyway to control the size of the crackle of a raku glaze?
I just learned the following in the last few months:
When glaze expansion is a lot higher than clay, you get small crackles
("Size 8 pot, size 7 glaze").
When glaze expansion is only a little higher, you get bigger crackles ("Size
8 pot, size 7 1/2 glaze").
When glaze expansion is way lower, lo the glaze doth flake off and rend pots
asunder.
I use Insight for keeping track of my glazes and it calculates expansion for
most materials for you. If you have it, you could play with your recipes
expansion there. Or, you might try adding some low-expansion frit to a test
and see what you get (I think 3124 is relatively low-expansion, but that's
from memory).
Good luck! I've been meaning to use the above to make a mat white large
crackle raku glaze ... should be ready real soon now.
Jeff Lawrence
Route 1 Box 394L
Espanola, NM 87532
jml@sundagger.com
505-753-5913 vox/fax
Jim Connell or set clayart mail on mon 28 oct 96
WINTHROP UNIVERSITY Electronic Mail Message
Date: 27-Oct-1996 03:16pm EDT
From: James Connell
CONNELLJ
Dept: Art and Design
Tel No: 323-2126
TO: SMTP%"CLAYART@lsv.uky.edu" ( _SMTP%"CLAYART@lsv.uky.edu" )
Subject: RE: Raku Crackle Control
I think it is a combination of a lot of different factors. Clay body and glaze
formula are obvious but also to be considered are thickness of pot and if both
sides (inside and outside) are glazed (compression). Cooling is also important.
Going straight from kiln to can is okay but I have taken pots (that need to
crackle) from kiln and sit them on a soft fire brick to cool them (crazing them)
and then go into the can to smoke them and get the carbon to stain the clay
body. Timing is important and the pot's thickness determines the time. I also
spritz the pot with water hastening the cooling time. Spritzing the interior is
disadvantageous as the water sits and bubbles and boils and I don't like the
final look.
This "slow pull" method also keeps the glaze from taking on the texture of the
combustible material. After it is in the can you can check it and see if you
like the crackle. You don't have to wait long, maybe a couple of minutes. Open
it and if it is not crackled enough, spritz it some more and smoke it again.
Obviously this method is only for the white crackle look or glazes that don't
need the heavy reduction look. Copper raku needs to be smoked right away or
you'll never get reduction lusters.
A friend of mine shook his can (garbage not butt)and thought it helped get
better crackle. I don't know about this but any ritual might help.
Another trick that works but is a mess is to smoke it in the can right away and
then yank them from the can and roll them in a metal bowl filled with old car
oil. It will not only crackle the pot but the oil ignites and the black smoke
darkens the clay in the cracks. Cool, eh! But beware the hot oil can be
dangerous and the pots are hard to clean.
Jim
Michelle H. Lowe on mon 28 oct 96
I'm interested in this too, and neglected to save the info when it went
around last time. A friend has a recipe called "Large Crackle" and she
remembers it has spodumene in it, but it's packed away for who knows how
long (she just moved). If anyone has this recipe I'd love to have it to
use in my newly functioning raku kiln :-)
Thanks friends,
Mishy
At 11:56 AM 10/27/96 -0500, gafergus wrote:
>----------------------------Original message----------------------------
>Hey you Raku experts:
>
>Is there anyway to control the size of the crackle of a raku glaze? I am
>using a clear raku glaze (Laguna) that does very good small crackle. I
>have seen several works that exhibit large crackle and I would like to
>try to acheive that. I've tried thicker and thinner glazing but it
>doesn't seem to make any difference. Does it have to do with the way it
>is reduced, or the clay body (I use Soldate 60)?
>
>Any help would be appreciated!
>
>Thank
>Gary Ferguson
Michelle Lowe, potter in the Phoenix desert \|/ |
mishlowe@indirect.com -O- | |
mishlowe@aztec.asu.edu /|\ | | |
|_|_|
http://www.amug.org/~mishlowe ____ |
-\ /-----|-----
( )
<__>
Don Jones on mon 28 oct 96
>----------------------------Original message----------------------------
>Hey you Raku experts:
>
>Is there anyway to control the size of the crackle of a raku glaze? I am
>using a clear raku glaze (Laguna) that does very good small crackle. I
>have seen several works that exhibit large crackle and I would like to
>try to acheive that. I've tried thicker and thinner glazing but it
>doesn't seem to make any difference. Does it have to do with the way it
>is reduced, or the clay body (I use Soldate 60)?
>
>Any help would be appreciated!
>
>Thank
>Gary Ferguson
GARY,
Crackle can be controlled by using your ears. Just out of the kiln, a hot
pot hasn't started to crackle
wait a while and you can hear it. By adjusting the time in open air you
can control the amount of crackle. (If your glaze thickness remains
constant)
Don Jones
claysky@highfiber.com
| |
|
