Need Help: Would like to know what I'm doing wrong (Interior kiln cracks)

[Rabbieatzpork]

Hey everyone! Im new to lamp working I started in Oct. Super fun! Lately I've been trying to sculpt more intricate pendants. I came across this design I like called "Alligator eyes" They look pretty nice. I was working on one yesterday and left it in the kiln. The next day I came back to pick up my work and noticed there were interior cracks in the eye. Total buzzkill. I'll attach images of my pendant and the cracks im talking about. Does anyone know what I did wrong? What can I do to prevent this from happening again?

Thanks.

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[Misfitman]

Some colors dont do so well with encasement, Another thing i notice is acute angles, Those are generally full of stress. i know it didnt crack near the acute angles, just saying maybe it led to more stress overall, leading it to crack. Im not pro, Just spitballin here.

[Misfitman]

Sometimes you can crack it in half on the crack and you will notice an air bubble that isnt melted round. generally you can find the reason it broke by looking carefully.

[Rabbieatzpork]

I had a hunch it could be something like that. Air trapped between the colors. I'll just run it under the flame for much longer, make sure that back is flat.

[Rabbieatzpork]

By chance do you happen to know a general rule of thumb as to what colors do better in encasement than others?

[Shattered Dreams]

they say most greens and sparkles dont do well.

but i think the newer green sparkles like papparazzi and jackpot are ok to use in deep encasements. i havent had a problem with them.

[lost nebula]

PyroChixRock posted a great murrine color chart. http://www.talkglass.com/forum/showthread.php?64869-Color-Database

Murrine is basically a deep encasement so colors that work for them should work fine.

And FYI Glasstronics green works great for encasement.

[Shaper]

Looks to me like you need to weld your glass together more. Your border color and loop are only melted to your center piece and not melted in. I'm surprised your loop didn't crack also. If you want sharp angles you need to sculpt them after everything is melted in.
From what I can see your cracks are not caused by the colors you used.
Heat is your friend, use more of it.
Have Fun.

[istandalone24/7]

better welds, and i see checks. it's a combo of your technique and the color itself. greens are problematic.

[Jimi The Don]

on top of everything that was mentioned previously, what's your annealing schedule like?