COE changing after multiple firings???

This is the main board for discussing general techniques, tools, and processes for fusing, slumping, and related kiln-forming activities.

Moderators: Brad Walker, Tony Smith

Post Reply
Amy on Salt Spring
Posts: 270
Joined: Sun Mar 09, 2003 5:43 pm
Location: British Columbia, Canada
Contact:
Contact Amy on Salt Spring

COE changing after multiple firings???

Post by Amy on Salt Spring »

Recently in another discussion Catharine mentioned that she had a piece that she had fired I think it was 17 times. I have often had pieces that I fired 5 or 6 times but never any more than that. I know that there are certain colors that can tend to change their COE after being taken to fusing temps again and again. I now have a piece that I have fired about 5 times and want to fire two more times. I'm getting a bit nervous about it because its relatively thick and I've never fired a thick piece so many times. Its BE black and white. I'm being very careful about very, very slow ramps up and down but do I have to worry about the COE changing after so many firings? I need an emoticon that shows nail biting...
-Amy
Top
Geri Comstock
Posts: 340
Joined: Mon Mar 10, 2003 4:16 pm
Location: Northern CA
Contact:
Contact Geri Comstock

Post by Geri Comstock »

I may be wrong, but my understanding is that colors like red, yellow and orange are the ones that are susceptible to COE changes over multiple firings. I fire my "Firebird" series red, yellow and blue pieces 6 times and haven't ever experienced this. I also fire pieces in the same series in red, black and white 6 times and haven't experienced this either. I wouldn't worry about it. I've fired pieces in red, black and white at least 10 times before with no problems.

Geri
Top
Brian and Jenny Blanthorn
Posts: 353
Joined: Mon Mar 10, 2003 5:25 pm
Location: UK
Contact:
Contact Brian and Jenny Blanthorn

Re: COE changing after multiple firings???

Post by Brian and Jenny Blanthorn »

Amy on Salt Spring wrote:Recently in another discussion Catharine mentioned that she had a piece that she had fired I think it was 17 times. I have often had pieces that I fired 5 or 6 times but never any more than that. I know that there are certain colors that can tend to change their COE after being taken to fusing temps again and again. I now have a piece that I have fired about 5 times and want to fire two more times. I'm getting a bit nervous about it because its relatively thick and I've never fired a thick piece so many times. Its BE black and white. I'm being very careful about very, very slow ramps up and down but do I have to worry about the COE changing after so many firings? I need an emoticon that shows nail biting...
-Amy
If U keep the temp low then the problem of stuff comming out of the glass will B lessened

If using side elements then consider baffling the elements 2 avoid thermal shock

Brian
Image
Top
Catharine Newell
Posts: 83
Joined: Thu Mar 13, 2003 12:33 am
Location: Portland, OR

Post by Catharine Newell »

Amy,

I have fired panels 20 times with no ill effect... HOWEVER, the largest percentage of my firings are tack fusing. I probably only full fuse an entire piece 2-3 times in that 20. I don't think you'll have any problems with your next firing.

Catharine
Top
jerry flanary
Posts: 158
Joined: Tue Sep 09, 2003 11:11 pm
Location: norfolk, va

Post by jerry flanary »

I think the COE change is most pronounced in the red yellow oranges that strike. Something about the crystals building up and changing the COE. There was some discussion of this at Craftweb. B&W should be ok.
j.

A lack of doubt doesn't lend certainty.
Top
Lynne Chappell
Posts: 186
Joined: Fri Mar 14, 2003 2:05 am
Location: Surrey B.C. Canada
Contact:
Contact Lynne Chappell

Post by Lynne Chappell »

I think the shift could be a real issue. No-one tests their glass for more than 3 firings. There probably isn't a known definitive answer for this.
Top
Post Reply

Return to “Techniques and Tools”