Coasters help!

[Peego]

I have just fired a batch of coasters and all but one has been a disaster! The top piece of glass has slid off the base glass slightly. This has never happened before. They were all ok when placed in the kiln and the kiln wasn't moved once turned on. Any advice greatly appreciated.
Thanks

[Sarah A]

Oh dear what a shame. I'm afraid I can't be of much help ive had it happen to one before and just thought it had slipped. I do put a small drop of pva glue between layers to stop them slipping while heating up and the glue burns out if firing to full fuse. For tack fusing I use honey!  I hope someone is able to explain why this has happened to you.

[Peego]

Thank you, will give pva glue a try next time.

[Barnacle Bay]

Agree with Sarah A & Peego use PVA glue. I generally put a number of pea size blobs about and let it dry b4 firing