Hollow versus solid in regards to the annealing process

[Shrimp]

Maybe the trend is just my imagination, but there appears to be a spike in hollow beads lately. I haven't been very successful at making them. It occurred to me that hollow beads would be less apt to succumb to thermal fracture during the annealing process, than solid beads. I'd like to hear the opinion on this subject from some of you more seasoned hollow bead makers. Thank you.

[RyanTheNumberImp]

Required annealing time is based on thickest cross-section. I don't remember the exact number, could have been 2-4 hours per inch? Its in the kervin book.

Anyway, you are correct. Hollow beads will need less annealing time than their solid counterparts.

[Jeri]

I make a lot of hollows and anneal them like solids, usually my kiln has both. I don't know what you mean by "thermal fracture during the annealing process" unless you are batch annealing cold beads. In that case, on the rare occasion I do that, I bring them to annealing temp very quickly (maybe twentiesh minuts) and never have had an issue. Jeri

[Carolyn M]

Ryan - when are you making more butterflies????
Sorry, thread derail

[Shrimp]

Carolyn, No problem. So Ryan, when are you making more butterflies? Thank you Ryan and Jeri for the tips. I guess what I was trying to get at, are hollow beads less apt to thermal crack...whenever that happens? I have had a number of my larger beads split in half along the mandrel. I thought that maybe being hollow, there would be less chance of this happening because there isn't that extra glass there. If that makes sense. The cracking on my beads has happened both in a preheated kiln, and in the annealing bubble receptacle.

[hyperT]

Technically it's 10 minutes per millimeter thickness held at the annealing point. However something very small and very thin may not need any annealing at all. Stress occurs when the surface of the glass cools but the internal parts are still expanded. As the internal parts cool they can put tremendous strain or stress on the surface and even crack the glass, as I'm sure all of you already know. I usually just flame anneal thin pieces in a "Dragon Fire?" flame. This flame is high gas and little ox. It has a light tan color to it. Annealing them in a kiln on a regular schedule certainly won't hurt them.

[JavaGirlBT]

I have heard anecdotally that hollow beads are in fact less likely to thermal crack than solid ones.