Jump to content
Sign in to follow this  
JoLinDesigns

Over Glazes

Recommended Posts

Can anyone tell me why my tiles that were previously fired to ^5 would break during a ^05 firing? I added an overglaze and refired to a much lower temperature. So why would they break at this point? Very frustrating!! Is there a trick as to how to fire this last firing? Ie. different than a bisque firing? Peeps in...peeps out...slow fire/cool? I fired preprogrammed at standard rate. Should I change this? Thanks for your help. Linda

Share this post


Link to post
Share on other sites
neilestrick    1,381

Many forms, especially flat ones, do not like to be refired. They don't handle the thermal shock and uneven heating very well. The top of the tile heats faster than the bottom of the tile and they crack. Try firing on stilts of some sort- even little clay coils or wads would work, or slow down the firing at the beginning and end.

Share this post


Link to post
Share on other sites
oldlady    1,323

thanks, neil, i wondered the same thing.  thought it might have to do with placement on the particular shelf in the same spot in the kiln.  shelves change shape without warping so we notice it .  have been taking pictures of the loading so i can refire in the same location if needed.

Share this post


Link to post
Share on other sites
Chris Campbell    1,088

Thanks Nell. Makes sense. But, will I not have problems with warping if they're on stilts?

In my experience, no.

The clay itself should not be moving much at those low temps ... I don't think your over glaze would cause warping.

But I could be wrong as my work is mainly with porcelain.

Share this post


Link to post
Share on other sites
neilestrick    1,381

 

Thanks Nell. Makes sense. But, will I not have problems with warping if they're on stilts?

In my experience, no.

The clay itself should not be moving much at those low temps ... I don't think your over glaze would cause warping.

But I could be wrong as my work is mainly with porcelain.

 

 

I'm thinking the same as Chris. A cone 6 clay should not have warping issues at low fire temps. But as always, test it first, and make sure the tile is evenly supported.

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  

×