Will annealing heal cracks?

Khaleesi Dane · #1 2014-09-12, 4:38pm

Hello, newbie here, seeking a little input. Last night I completed a stunning marble, however, as I was giving the little nub the last flame polish, apparently the marble marver was cool, and the marble cracked. I immediately put it in the fiber blankets, and was wondering if I annealed it with the rest of the batch, would the crack heal? Or is it just pretty frit now?

And how do you flame polish your marbles with out this happening? Tweezers? Heat the marble marver?

It is 104, mauve white and clear, if that matters.

Thanks!

jamie lynne · #2 2014-09-12, 4:49pm

Annealing will not fix cracks.

squid · #3 2014-09-12, 5:12pm

Annealing reduces stress in glass - once it's broken, the stress is relieved.

You might be able to bring it to annealing temp and then try (CAREFULLY) reheating it in the flame to heal the cracks and then put it back in the heated kiln.

Khaleesi Dane · #4 2014-09-12, 6:06pm

Thanks squid, I was wondering if that might work. Since I learn best by practice and hands on, I think it might be worth trying. Figured I would ask first tho, in case cracked glass has a habit of exploding or something!

Is it worth a try, or risky and fool hardy?

Khaleesi Dane · #5 2014-09-12, 6:14pm

Thanks also Jamie Lynn. How do you prevent these cracks from happening yourself? Tweezers? Warm marver, practice?

Talonst · #6 2014-09-12, 6:47pm

Every time the glass is touched by a tool or by graphite it needs to be reheated gently and evenly.

Stress is formed from uneven heating. A sharp flame on a small spot will do it.

Allowing the bead to cool too much - keeping the bead above the flame in the column of rising heat helps.

If you do try to fix a crack start with a propane flame and allow the glass to heat up very slowly, then introduce oxygen very slowly. The thicker the glass the harder it's going to be.

jamie lynne · #7 2014-09-12, 6:47pm

I'd start by making sure my final punty attachment is cold sealed so it will break away easily. Then after I have it in my grabber, and have the punty snapped off, there should be very little to fire polish, and there won't be a need to put it back into the mold.

If it happens again, I'd just attach another punty, and melt the crack back in. It's easier to fix it then than to have to reheat and rework after it has cooled.

squid · #8 2014-09-12, 6:56pm

Quote:

Originally Posted by Khaleesi Dane

Thanks squid, I was wondering if that might work. Since I learn best by practice and hands on, I think it might be worth trying. Figured I would ask first tho, in case cracked glass has a habit of exploding or something!

Is it worth a try, or risky and fool hardy?

It does, which is why the carefully lol

Bett · #9 2014-09-15, 12:20am

I do recommend long sleeves, natural fiber turtleneck and face protection when reworking a thick piece of glass out of the annealer, as there is the potential for somewhat larger flying bits of hot glass. ^_^

istandalone24/7 · #10 2014-09-15, 11:12am

u talking boro or soft? both can be put back in the kiln, heated up to garage temp, soaked for a little while (hour or so) then pulled out with hot punty and reworked.

artsyuno · #11 2014-09-15, 2:13pm

If you're using soft glass, I'd turn the kiln up higher than your garaging temp (1050ish). It'll make it easier to re-introduce it to the flame.