Why the beads crack during cleaning?

[chimehk]

5324
I can't understand why my clear beads keep on cracking during cleaning the bead holes. I'm using a pin vise with diamond drill bit ends. I soak the beads in the water and scrub them several times to clean them. But most of the clear beads will have a crack split line. This don't happen to the opaque beads. I just can't understand why. What did I do wrong? :cry:

[Mr. Smiley]

It may be happening to the opaque beads and you just can't see it. This is probably a problem with your annealing. The beads still have a lot of stress in them. What is your annealing program?

[MikeAurelius]

Either that -or- they had heat shock breakage before they went into the kiln. How long do you sit and admire them before you pop them in the kiln? I usually see this with my beginner class students - they take a minute or so to examine the bead and don't flash it in the flame to re-heat it one last time before they pop it into the kiln.

Your beads show heat shock cracks - and this is usually from allowing the beads to cool too much before they are put into the hot kiln.

I tell my students that there will be plenty of time to admire the beads AFTER they are annealed, to take the bead and put it into the kiln just at the point where the red heat glow is almost gone.

This can also happen if the bead is cooled too much and put back into the flame without the dance to pre-heat the bead. Remember, if the rod shatters when you put it into the flame cold, your bead will do the same.

[chimehk]

I don't kiln annealed my beads. I'm just a newbie and my place is small and can't have a kiln in it. I just use like the vetriculite but these are white ones instead. Maybe I don't put my beads deep enough. Will try to be careful in annealing then. Thanks

[chimehk]

Also, the beads crack during cleaning and not before. When I took it out, I don't see any cracks. On the first scrubbing to clean the bead hole, it is still fine. It usually happen on the 2nd or 3rd scrubbing then the crack happens. Is this still to do with the annealing or my cleaning method????

[cghipp]

The cracks re already there when you start cleaning, but the pressure from the cleaning makes the cracks widen and show up.

Try putting your beads in the vermiculite when they're a little hotter and leave them in there until you're sure they've totally cooled. Also, before you do that you can bring the temperature down a little more slowly in the flame. After the bead is made, simply heat to glowing, let cool a little, heat to less glowing, let cool a little, and so on. Do this maybe four times, moving further back in the flame (away from your torch) each time. It'll take about a minute. Then, when you put the bead in the vermiculite the outside temperature will be closer to the inside tempurature and your bead will have more of a fightng chance.

Good luck!

Courtney

[MikeAurelius]

Chimehk - putting beads in vermiculite is not annealing. I don't know if you know this and perhaps just used the wrong word, but you cannot anneal beads by putting them in a pot of vermiculite.

The only way to anneal beads is to use a kiln. Putting beads in vermiculite only allows them to cool down, it does not provide a method of holding the beads at the annealing temperature long enough to allow the stress in the bead to relax. This process requires a kiln, and only a kiln can do it.

Beads that are not annealed should not be sold or even given away - there is always the possibility that the bead may break which may injure someone.

Now, as Courtney said, it's possible that you are putting them into the vermiculite too cool, they should be put in just at the point when they have stopped glowing. They should go deep into the vermiculite, at least 2 inches. It's possible that your container is not big enough to hold enough vermiculite.

[chimehk]

Thanks Mike. Yeah, get the terms mix up :) What I mean is cooling them. You got it right that my container is not big enough. I just use a mug. Will get a bigger container to do it next time. It just boggles me that it only happens with the clear beads but maybe I just couldn't see the cracks on the opaque beads since the surface looks alright. Thanks for all your help. This is all so new to me and alot of things I just couldn't understand why it happens.
Thanks everybody for all your advices =D>

[MikeAurelius]

See if you can find a 5 pound coffee container, that seems to work very well for a lot of people - others use an old crock pot (don't bother to turn on the heat - it's worthless to heat vermiculite ;))

[cghipp]

I used to use a terra cotta pot (like you would put a plant in). Very cheap!

Courtney

[Dale M.]

Use something like a 2 or 3 pound coffee can!...

Dale M.