CIM cracking

[Trudi]

Does anyone know whether these CIM colours would behave OK if encased with CIM clear glass or would it still be the same issue. I have used some of those dodgy colours but not encased them. At that point I was batch annealing and did them on the same programme (had not had any info from sellers that there were any differences in the annealing requirement). Anyway I had them for a while before selling and did not have any cracks appear later.
Kaz

When I asked Kathy @ CIM about the Celedon she said it didn't like lauscha. It had cracked on me before - but I then tried it with the new effetre and it was fine! Not sure if that helps!

[Mand]

I find beads I make with the milky colours like halong bay have a tendancy to crack..

All my Cirrus ones have cracked today 

[Soo]

Does anyone know whether these CIM colours would behave OK if encased with CIM clear glass or would it still be the same issue.

I'd love to know this too. I really should've ordered some CIM clear with my last glass order.

Celadon definitely doesn't like Vetrofond encasing either. It has rather put me off CIM glass altogether to be honest as I encase lots of my beads.

I have wondered whether some of these colours really have the COE value that they say.

Drew Fritts recommends that the real test of an annealed marble is to put it in the freezer (in a sealed plastic bag). I think the same must be true of an annealed bead - if it doesn't crack after that you can be pretty confident it won't after making up into jewellery. (Drew also jokes that if it does crack, you'll be glad it was in the plastic bag).

[Soo]

There was a bit about this in another thread http://www.frit-happens.co.uk/forum/index.php?topic=3745.0 and we kicked about the theory that it might be encasing on cold days. There still haven't been many warm days since then for me to run any experiments but seeing as all the other beads I have encased on cold days are OK, I'm doubtful this is the reason.

BUT I went back to the batch of earlier beads that I mention in my postings in that thread and half of those have cracked; they survived for several days and then I stopped looking when I put them away. I'm so grateful I never used them in jewellery (because of the later batch where everything cracked, I lost confidence in all CIM encased beads).

Today, I pulled a stringer of Vetrofond clear and CIM Celadon. I tried really hard to make sure I had a 50/50% mixture of both glasses, one on top of the other. After pulling the stringer, I cut the middle foot out and it looks pretty straight by eye but when I compare it to a ruler, the centre of the stringer was bent out by 2mm. I'm not sure if this is enough to show incompatibility. Now I've finished making beads, I realise I should also have run this test using an Effetre glass as well - as that may well do the same! (Note to self to do this tomorrow).

I have also used the stringer ends containing both glasses in equal proportions to make a bead with. I'll be interested to see if that cracks too or whether it's just encased beads.

[Soo]

The stringer that I made with equal quantities of Effetre Periwinkle and Vetrofond Clear came out straighter than the CIM Celadon and Vetrofond Clear. The Effetre one has an off-set of 1mm whereas the offset on the CIM one is 3mm. I don't know if this is enough to prove the glasses aren't compatible and I imagine it would need repeating several times and by others before it could be viewed as conclusive.

The bead that I made with 50/50 mix CIM Celadon and Vetrofond Clear (not encased) has survived being frozen overnight so I'd be pretty confident about making jewellery out of it now.

I think what I'll do in the future if I encase CIM colours is to put the beads in freezer overnight and if they haven't cracked by morning, then I'll consider them safe but I think I'm just gonna leave CIM colours alone fullstop.