Home › Forums › Glass Fusing › General Fusing Discussion › Making small cabochons with opalescents pickup kiln paper. › Separator pick-up
You may be firing too hot or too long. You give no information on the firing schedule or conditions, so this has to be speculation.
Fire lower and longer – peek in periodically to see what is happening. As soon as the glass rounds, go to anneal cool. On the next firing set the temperature 20C lower and fire for longer. Peek in periodically to see how long it takes for the glass to ball up. Record this and you will have a reference for the future.
As opals always are more prone to pick up residue from the separators, you could put a piece of clear glass under the opal. Less work than cold working.
In general, I can get small pieces like this to ball up at rounded tack temperatures. At these temperatures you should not be picking up separator residue. This is why I think you are firing too hot.