smallest mandrel problems

[topher wren]

I just got back from a trip to indiana, where my sister and I made beads the whole week. we used different mandrels, she used the smallest sized, I used a medium size mandrel. at the end of the weeK she only had 4 beads that survived. all them cracked, a couple of beads I made on the smallest mandrels also cracked. has any one else had a problem using small mandrels? I am about to throw them away.

[Carolyn M]

I use 1/16th mandrels for all my beads and never have a problem. Were you using smaller mandrels than that? Are you batch annealing or straight into a kiln? Pressing? There are so many variables, but mandrel size has never seemed a huge factor in bead cracking in my experience.

[tasminann]

I use mostly 5/32 (one up from 1/16) and don't have a cracking problem.

The next question: what did the cracking look like? Straight along the mandrel (almost always thermal) or more of a webbing crack? A webbing-type crack would be compatibility. Any chance you all might have been using 2 different COEs or 104 COEs that are known incompatible with one another?

[J. Savina]

Cracking doesn't only happen by not annealing properly. It could also be a COE problem. (Like Gail said) So, one question to ask is: What kind of glass were you using, and were all the glass the same or as close to the same COE as possible?
I'm so careful when I fuse or lampwork that the co-efficient of expansions of the glass are as close as possible. The longevity of the pieces or beads depends on 2 things. COE first, then proper annealing.

The glass I use may not cost that much, but my time is worth alot to me. It's heartbreaking to have spent so much time on something to have it fall apart on you.
J.

[chrissij]

I use teeny mandrels, and have no problems.

[RSimmons]

I've used mandrels down to 1/29 and have not had cracking problems. The mandrel isn't the issue, check your annealing schedule, type(s) of glass and how long you let them cool before you went into the kiln. Remember that small pieces loose heat more quickly.

Robert

[teachertracey]

If you're using teeny mandrels, are the beads too teeny? Sometimes I have cracking when the beads are just too smushed or too tiny.

[Jody Lee]

Yes, there should always be as much glass on either side of the mandrel as the mandrel is thick. I.E..if your mandrel is 1/16th the bead should be a minimum of 3/16ths thick through, provided the mandrel is in the middle of the thickness. That, and warm that baby to a dull glow before putting it in the kiln - insurance, baby!

[topher wren]

I was trying sims messy color hempaluff or something like that, I did moretti blick with raku frit. the beads out of moretti black cracked right around the mandrel. not length ways but similar effect as a home window with a bb hole shot in it. the sims mess cracked in length as the mandral . I am not sure of the size of the mandrel , but it is small, perfect size for flex stringing wire to go through . It came in a glass torch kit i got years ago.

[RSimmons]

The raku frit isn't the same COE as the Effetre back and you probably didn't have enough mass of black to absorb the difference. That kind of cracking is from incompatibility. The sims cracking is thermal.

Robert

[topher wren]

Thanks for the in put RSimmons, I have to try the messy collor again. I recently did another black with raku frit and it came out.