Crank Clay, Chimneys and pitfiring

[vialde]

Hello,

I've got a little project on the go where I'm trying to convert an old electric kiln into a down draft gas kiln.  I'm at the point  where I need to construct a chimney and I've done loads of research on designs for this.  The easiest and most obvious solution is to build an external chimney out of brick.  But I'm doing this on an extremely limited budget so buying enough brick to make a safe chimney is out of my reach at the moment.  I do happen to have access to a load of Crank stoneware clay.  So I was thinking I could either throw a chimney in sections or handbuild one out of slabs.  Now here's the nub of the question.  Should I build the chimney in situ with geenware components and fire the kiln to finish it off?  Or as I also have access to a barrel and a load of sawdust and offcuts, should I pitfire the components and then build the stack from there? 

Any thoughts, advice, horror stories would be greatly appreciated

 

Cary

 

[Mark C.]

You need bricks at the bottom and where the flue is -beyond that clay can work but expect lots of cracking and so that parts needs to be wrapped in wire to keep the pieces together .Add the sawdust to clay so it burns out when heated .

[neilestrick]

If you pit fire it, it will probably crack from the uneven heating. If you try to fire it by running the kiln it's going on, it will probably crack from the uneven heating. You'll need to add a lot of sawdust, and a bunch of silica sand wouldn't hurt, either. That said, trying to build it and attach it to the kiln is going to be very difficult, and probably not worth the effort. I would say if you really want to go that route, then make yourself some bricks out of that blend, fire them in the kiln up to bisque temps using the kiln as an updraft, and then construct the chimney with them. The other option is to simply fire your electric kiln conversion as an updraft until you can do the downdraft with purchased bricks.

[Mark C.]

Salvage some metal  for the stack and use cheap fireplace bricks and expect short life on the bricks.You will need about 2-3 feet of bricks