I made some beads using base Effetre white, then thin encasing half of it With CIM Leaky pen, the other half With an Effetre colour (don't remember the name now), semi opaque. Then added a stripe With Clio where the two encasings met. The beads were then squeezed With a Corinna tool, Reduced the Clio and in to the garaging kiln.
All but two has cracked, mostly Down the middle to the mandrel, but only the half of it; the half encased With Leaky pen. The cracks actually occur when I clean them With the bead reamer. No one have cracked on the other half, so I think this is a matter of compatibility rather than thermal?
In the case it is incompatible glass there's nothing to do I guess, but if it is thermal I would be tempted to try to reheat them in the kiln. Problem is, they are off the mandrel and clean, so has anyone tried to put a bead back on a mandrel? How to handle the bead release?
If they have cracked down the line of the mandrel the problem is almost certainly thermal rather than incompatibility.
It's unlikely, if they have been removed from the mandrel, that you can reheat, but if they are useless anyway why not experiment?
I have in the past taken a smaller clean mandrel and recoated it in bead release. While still wet, introduce it into the bead hole and let dry so that the release acts as a glue. If its a thermal crack down the mandrel so that you have two halves of bead, there is less chance of reheating successfully. In that case, I've turned the two halves into cabochons. When wanting to reheat, put into a cold kiln and bring the kiln up to annealing temperature. Still leave the bead in at that temperature for at least 30 mins so that the bead is heated all the way through. Slowly reintroduce to the flame and pray to the bead gods.
Quote from: Irene on January 31, 2015, 04:43:56 PMThe beads were then squeezed With a Corinna tool, Reduced the Clio and in to the garaging kiln.
What shape and how thick are the finished beads? Some shapes, eg lentil, are more prone to cracking. A thin wall (between mandrel and surface of bead) may be problematic. Also a tool or press sucks heat out of the glass rapidly - did you reheat fully before the reducing stage? If not, I imagine the bead could be highly stressed or already cracked before it goes into the kiln... In any case, I agree with Dragonfire that it's more likely thermal than incompatibility.
You could try Pat's method... though I'm not sure a prayer will be enough for the bead gods - have you got anything you could offer as a sacrifice?
This is a Picture of the beads that have cracked, and the two on the far right that have made it out of the oven in one piece. What I think is a Clue to it not being thermal cracking is the fact that only the blue has cracked on all of them. The Brown is intact. What do you think?
(http://i299.photobucket.com/albums/mm317/ACDonMyMind/141f5e55-5318-4a9f-8f87-8ae989c31dad.jpg) (http://s299.photobucket.com/user/ACDonMyMind/media/141f5e55-5318-4a9f-8f87-8ae989c31dad.jpg.html)
Leaky Pen is incompatible!! Don't use it unless you use it on it's own.