What have I done wrong? Annealing problem

[Fruddy]

Its a gutter having something that you are really pleased with you break or crack isn't it??

Loving the colours in the one that broke..... try and make it again tomorrow???

[awrylemming]

Funnily enough, I was just mourning it before I read your post - you've inspired me to do it again, thanks for that! 

[Fruddy]

I had a focal break on me last weekend and I could have cried.....it was made with either Nyx or Psyche (can't remember now) and encased with clear and for some reason I had managed to get the post wonderful peacock blues out of the DH and encased it just right, capuring all the shine.  It fell in half when I tried to get it off the mandrel.

I sat looking at it for about 20 minutes, wondering whether I should try supergluing it together but in the end i chucked it into my pot of bead release, so at least it is still being useful as a bead release mixer if it isn't being pretty anymore!

Look forward to seeing your next attempt.

[Shirley]

I find it's usually the area at the holes that needs the heat, and it's the easiest part to miss!

Fruddy, rescue your broken bead, clean it up and then slump it into a pair of cabs in the kiln. Waste not, want not

[Hotglass28]

Am I right in thinking that thermal cracking of glass will do it there and then and a COE problem will do it then, 5 mins later or even years down the line.

I reckon it was a COE problem. . Maybe it was that?

[Trudi]

A COE problem would crack like crazy paving - if that makes sense!

[awrylemming]

Definitely not a COE problem - I keep my different coe's in different rooms!  Better safe than sorry. 

[Kalorlo]

Am I right in thinking that thermal cracking of glass will do it there and then and a COE problem will do it then, 5 mins later or even years down the line.

Not necessarily. Or, at least, thermal cracks can be there but not visible until they've widened later.

[Hotglass28]

Even if you have one COE, colours, and batches can alter the COE very very slightly. So it might still be a COE problem. This of course is also different with every manufacturer. 

Somewhere there is the techno geekery article about in depth explanations on what goes on with COE and the myths. Cant remember where now?


How about trying it again using exactly the same glass in roughly the same amounts, the same way you did it before and veiwing it under a polarising lens?

Denise

Was it Dennis Brady who said in his PDF that just because mixing of coes has been done 100's of times doesnt mean there is a problem.

[Hotglass28]

http://www.warmglass.com/Glass_compatibility.htm

This wasn't the one I was on about but a start.

[awrylemming]

I think I may buy a polarising lens from Sam - I'm a little concerned about whether or not my kiln is correctly annealing so it may be an idea to check that they are safe for use.  I keep meaning to and never get round to it, but feel I should now.  I try not to mix my manufacturers too much, especially for large beads, but sometimes just can't get the colours I want otherwise.  I think this was effetre and CIM, so I may try the same bead with a similar CIM colour - not effetre, I only have 004 clear.