Jump to content
Sign in to follow this  
macdoodle

Raku firing

Recommended Posts

I just fired 2 raku projects.

 

The first came out all intact and was more slowly fired.

 

The second, a porcelain paper clay was fired faster had huge cracks in the main body, though the head (a thicker piece) and a hat (thinner lighter )were ok.

Is there a recommended firing schedule and does that change for paper clay?

 

The instructor does a preheat and then chooses the temp rate to get to cone 06, but if someone knows a recommended schedule for paper clay, I could ask to use that next time.

Share this post


Link to post
Share on other sites

a-ha, the first was a stoneware.

 

so porcelain and raku are just a bad combo -and I just got lucky on 2 out of three pieces surviving, THANKS!

 

maybe my next try i'll do a stoneware paperclay and see what happens :)

Share this post


Link to post
Share on other sites

I have successfully raku fired porcelain, but it was totally dumb luck ... did not care if it worked, so it did.:P

 

Paper helps in the pre-firing stages of raw clays by making them stronger and easier to handle and work with ... but it is burned and gone from clay after 451F ... a very low kiln temp. After that you are only dealing with whatever clay body it is. For pit firing and raku, paperclay's benefits lie in the fact that when the paper burns out during bisque, it leaves lovely holes behind to capture glazes and gases.

Share this post


Link to post
Share on other sites

If you are going to fire a porcelain clay body as raku (tough to do).... it is best to put them in the first heat-up firing of the kiln, rather than load into a pre-heated kiln. Then bring the kiln up a bit slowly to the maturity of the glazes. When pulled for post firing reduction, smother it in dense combustibles (like sawdust) that retard the cooling, and let it slowly cool right there....... do not water quench it.

 

As has been said, porcelain does not like thermal shock. The only reason to use a porcelain for raku is the white body background. And that can be accomplished with ANY forumlation of a body that is basically white. It never is getting fired to the vitrifaction point.... that is the whoe rationalle for HAVING porcelain. So try a differnt more thermal shock resistant white-ware body with a buinch of molochite (white) grog in it.

 

best,

 

.......................john

Share this post


Link to post
Share on other sites

People do use porcelain for saggar firing in raku kilns but it is a slower firing and lower temperature.

As John says the initial firing would be a good place to try it since that is slow as well. I would also

recommend air cooling after the reduction in a combustion chamber. I would.t dunk it in water. The density is still tight

enough to get shocked.

Marcia

Share this post


Link to post
Share on other sites

"The only reason to use a porcelain for raku is the white body background ..."

 

Well, how about just to see if you can do it? tongue.gif

Welcome back to the craziness John!

 

 

Oops... I forgot about the "perverse Don Quixote syndrome" reason. wink.gif

 

I'm still terribly jetlagged so not really "back"....... coming back to the West from the Far East tends to "peak" about 3-5 days after return........ then it slowly gets better. I'm at the peak time now. Feel like I got hit by a truck blink.gif .

 

best,

 

.........................john

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×