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

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  #1  
Old 2015-02-11, 1:26am
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Mina Mina is offline
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Default Pop off

I made some post earrings and put them into the kiln. They were nice and toasty when they went in. When I removed them from the kiln at the end of the cycle all of the earring toppers had popped off, leaving a thin layer of glass on each of the posts. Why did this happen? I used effetre 104 glass and 104 frit. The toppers where about 1/4" from the post to the top of the dome. Was it due to different expansion rate between the post and the glass? Will this happen every time or is there something I can do to prevent it from happening again?
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  #2  
Old 2015-02-11, 5:38am
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Michele R. Michele R. is offline
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Norma, I've had this happen as well. I don't have an answer as to why it happens, but my solution was to wrap some glass around the flat part of the post so that part is completely encased in glass. Make sure to keep it smooth, since that part is against the ear.
I'm hoping others will chime in with their tips, I just wanted you to know I had the same issue...
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  #3  
Old 2015-02-11, 6:01am
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Default Without actually seeing anything.

There can something other than COE that plagues us.

Even though the COE of both glasses are considered to be the same.
The viscosity of the two glasses may differ a lot causing undo stress.
In other words if one of the glasses gets very soupy and the other is
much harder to melt it can cause stress when combined together.

You can test the two glasses to see how they melt before beginning a
project. Do a stringer test if you are unsure.

This may or may not be your problem but we should bear it in mind.

Have fun, Wayne
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  #4  
Old 2015-02-11, 6:30am
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Kalorlo Kalorlo is offline
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Did you warm the end of the post so it glows (only just dully) before you applied the glass to it? I've never had this happen.

I make mine on surgical steel posts and i know people who use sterling. The ones I use are from Vetromagic and have no flat ends, they are just posts. What metal was it?
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  #5  
Old 2015-02-11, 6:37am
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Default Metals

Metals have COE's too.
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  #6  
Old 2015-02-11, 8:13am
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Hmmm....maybe it was the metal then. I believe they are stainless steel. I did warm them just until there was a light glow before adding the glass.
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Old 2015-02-11, 8:44am
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I think metal cools faster than glass so you need to make sure the post is nice and warm before it goes in the kiln. It sounds like the pad of the metal post is drawing heat from the base of the glass dome.
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  #8  
Old 2015-02-11, 8:48am
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Quote:
Originally Posted by Margram View Post
I think metal cools faster than glass so you need to make sure the post is nice and warm before it goes in the kiln. It sounds like the pad of the metal post is drawing heat from the base of the glass dome.
That's what I was thinking it might be
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