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Tips, Techniques, and Questions -- Technical questions or tips

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  #1  
Old 2016-12-16, 6:05am
shtayim shtayim is offline
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Default Cracking's problems

Hello everyone
I have a little problem with my beads. They crack !! Almost all of them !!
I would like to know if you could help me to find what I do wrong.
I work little pieces with COE104 glass. I use a pinpoint neutral flame to do a detail work and, as I want to batch anneal them (I don't own an annealer yet), I try to "flame anneal" them (I roll the bead in the back of the flame for 2/3 minutes), but they crack in the vermiculite.
Have you ever had this problem ?
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Old 2016-12-16, 7:38am
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Are you keeping the entire bead warm while you do the detail work? (roll it around in the flame to warm often, so the back doesn't get cool)
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Old 2016-12-16, 8:20am
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Odds are that the vermiculite isn't enough insulation to let them cool slow enough.


The hardware stores have these torch resistant pads in the pluming isle that you can get a pair of and put your beads in between them.

Then it will be a matter of learning heat control; don't admire your work after you make it and really give it a prolonged gentle heating in the flame before putting it away in the blanket.

Then leave it in there for as long as you can without peaking.
I have forgotten how long to leave it for a minimum but I would give them at least some 6 hours if not 10.

Maybe someone else here remembers just how long it takes to cool properly in a blanket.
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Old 2016-12-16, 10:17am
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And can you show us a photo of your beads that are cracking?
For instance, the warm colors (red,orange,yellow) do not like being encased unless you sandwich them, like clear, red, clear.
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Old 2016-12-16, 12:17pm
Diane (clarus) Diane (clarus) is offline
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2-3 minutes of "flame annealing" is way too long. I do about 30 seconds before putting mine in annealing bubbles and rarely get a thermal crack.
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  #6  
Old 2016-12-16, 1:29pm
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My bet is that the bead is getting too cold before flame annealing. You can't always do all your fine work without some "insurance heat" part of the way through, sometimes repeatedly. When in doubt, give it some a bit of extra heat throughout the decoration.

Good Luck!

Mary
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Old 2016-12-16, 2:36pm
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is your vermiculite warm?

I used to make small beads and spacers first to warm up the vermiculite before doing any larger beads.

I'd tap the bead on the edge to ensure it was solid, but still good and hot before putting it in.

and yes only needs 30 secs of flame anneal, and keeping it thoroughly warm while working on it.

What kind of cracks? Straight and the bead splits in two? or crazy cracks?
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  #8  
Old 2016-12-17, 8:02am
shtayim shtayim is offline
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Thank you for all your advices
I don't know if the photo is clear enough, actually the crack is straight and the bead split in two.

I don't think it's a compatibility's issue. My beads are sculped (it's quite a presomptuous word for what I manage to do ), and I rarely add encasements. Until recently, I worked with a torch head and I had no problem, but now I have a Bethlehem Alpha and my beads crack. Maybe I work too hot, but I tried to put less oxygen and it didn't change anything.

Do you think I can use a pinpoint flame and sometimes increase the flame's size, or should I alaways work in a bigger flame?

I'll try to "flame anneal" just 30 sec as you said and to warm the vermiculite.

Are torch resistant pads really better than vermiculite ?
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  #9  
Old 2016-12-17, 11:43am
Floorkasp Floorkasp is offline
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Like some of the others, I think your bead is probably cooling too much while you do the detail work. When I looked at some of the demonstrations from Corning glass, they gave me a nice sense of how often I needed to give heat to the 'base bead'. For example this one, by Leah Fairbanks. Start at 35 minutes: you see she does details, but quite often heats the entire bead. https://www.youtube.com/watch?v=3_pQAAQWeyI
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Old 2016-12-17, 12:02pm
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It is only my opinion but I think the pads are better because they stop air movement better than vermiculite.

But:

You really have to be very consistent about getting enough even heat into the inside of the bead before parking it what ever you are using to slow down the cooling.

Not peaking and not trying to stick another bead too close to the last one is important.

It's often the moving things around after putting it to bed that opens the cocoon of warmth and lets the heat out too quickly.
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Old 2016-12-17, 12:09pm
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I haven't watched the video Floor linked yet, but I think it would be good to watch it. It is always a benefit to see the right way for me at least.
And yes, I think the bead is not getting the good insurance heat to keep it happy all the way through as you work it, and then before you put it in the cool down material, whatever you use.
And have you checked out annealing bubbles? I have read that some people think they hold the heat better than vermiculite, although I can't swear to that personally.
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  #12  
Old 2016-12-18, 2:32pm
shtayim shtayim is offline
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Ok, thank you all with all of this, I should manage to do it right !
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  #13  
Old 2017-01-27, 10:32am
shtayim shtayim is offline
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I come back to you with good news
My little sculptures don't crack anymore, and I would like to share what I've changed if it can help someone:
1) I work with less oxygen in my flame
2) When I shape one side of the pearl, I regularly stop to warm it up globally
3) After having done it, I put my bead in ceramic pearls
4) Before I start working, I heat the ceramic pearls in a rice cooker

And for those which crack nevertheless, I melt them again and I manage to save some of them.

Thank you again for your advices guys, you've halped me a lot!
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