help needed for cracking beads

BoniBell · #1 2006-06-23, 4:11am

HELP. Please. My beads won't stop cracking. I thought it was my kiln, because I was batch annealing my beads.

Now I have a Paragon sc2 electric kiln which I keep on the whole time I'm working. My kiln is 2 steps from my work table so the beads go out of the flame into the kiln in 30 to 60 seconds.

The cracks are mostly in my more complex beads, frequently under the decoration. The cracks do not go all the way through, they are like spider webs on the surface.

If someone could give me a hint where to start investigating the problem I would really appreciate it.

pam · #2 2006-06-23, 4:33am

Spiderweb cracks are due to incompatibility. They usually, but not always, run from the incompatible glass. I would say, for whatever reason, one of your glasses are of a different coe.

BoniBell · #3 2006-06-23, 8:33am

Thanks. I'll try a couple of simple combinations on the glass to see which one may be the problem. I do mix my Effetre, Vetrofond and Lauscha pretty wildly. I'll have to dial it back a bit.

Emiko · #4 2006-06-23, 10:13am

Lauscha is not always compatible with Effetre or Vetrofond while Effetre and Vetrofond don't have problems with each other.

Emily · #5 2006-06-23, 1:33pm

If you're encasing with Lauscha clear, it needs to go into the kiln with the encasing still glowing. Don't wait for the glow to go.

Effetre "special" colors -- the opaque reds/yellows/oranges/browns -- don't always like to be encased. Try putting down a core of whatever clear you're going to use for encasing, then a layer of the special color, then the encasing. Oh, corals fit in the "special" category, too. There are some shades of coral that I never succeeded in encasing, even with a clear core. The "tequila sunrise" -- pinkish center with a mango-yellowish outside -- coral cracked whenever I tried to encase it.

Did you get any of the Kugler 104 clear? People were reporting some problems with cracking with that, although I also heard that if you heated your bead thoroughly to make sure that the encasing was well adhered to the base bead it wouldn't crack. I've never gotten around to trying mine.

If there are particular colors that always give you cracking problems, try a stringer test. Make a stringer by overlapping the rods about an inch and heating. Don't twist and don't allow the colors to mix. You need to keep them separate -- you should be able to see where the two colors meet in the heated glob. Pull the stringer as straight as you can, then look at it. If it curves, your glasses aren't compatible.

artwhim · #6 2006-06-23, 11:20pm

Lausha opaque purple hates being encased even in small amounts.

BoniBell · #7 2006-06-24, 7:35pm

The compatibility problem may be a problem with my frit. I make my own frit from my rod ends and I only have Lauscha, Effetre and Vetrofond. Most of my cracked beads are coated with frit and the cracks are where the raised flowers are on top of the frit. Beads with the same frit but no decoration on top do not seem to crack.

I have no idea what is in any blend because I decided not to make recipe notes. Some dumb idea about every bead being a unique work of art. Now I think I should at least list the color numbers when I make my frit so when something goes wrong I can narrow down the problem.

Everyone has been so good at sharing their observations. I really appreciate the help.

Emily · #8 2006-06-26, 9:20am

Can you post a picture that shows the cracking? It's very odd. Frit generally is such a small proportion that it doesn't cause cracking. Are you sure there's no one color (or maybe two colors) common to the beads that are cracking? You might have gotten a piece or two of glass that was labeled as Lauscha/Effetre/Vetrofond but was really something else.