gold nugget fused in glass

[Dianne Van de Carr]

I've been asked to fuse a special heart shaped gold nugget between 2 pieces of glass to be turned into a pendant. It isn't especially thick but is much thicker than gold foil, which I have successfully fused.

For the first attempt, I sandwiched the nugget between 2 pieces of 1/2 inch circles of clear Bullseye with little "chads" of clear glass to support the top piece and allow air to escape. When I opened the kiln, the top piece of clear was about 2 inches away from the bottom- like some force had sent it flying! I tried again and this time it fused but this morning I noticed a small fracture line around the nugget. This is OK because it is the test piece but I really don't want the piece with the heart shape to crack. Any ideas how to avoid this happening again?

The experiment piece was fused to 1500 and held 15 minutes. I annealed for 30 minutes at 900.
Dianne

[Stephen Richard]

Not everything can be encased in glass. Perhaps this is a case for acrylic?

[Judd]

How big is the nugget? And, talk about a $$$ learning curve? Really, really thin things work well fused between sheets of glass. Like the thinkness of a piece of paper.

[Dianne Van de Carr]

It's really small, about 3 mm. My customer said it was about $25.00 worth of 24K gold but he was willing to take a chance. I've successfully fused gold foil and copper wire and that was why I was willing to give it a go. He seems happy with the results and I hope it will hold up for a while.
Thanks for your input.
Dianne

[Dairy Queen]

A 3mm nugget requires about 8mm of glass to encase it. Two sheets of 3mm is not enough to encase without stress.

[Brad Walker]

A 3mm nugget requires about 8mm of glass to encase it. Two sheets of 3mm is not enough to encase without stress.

I'm not sure I understand this. Why would a 3mm piece of gold that's thin, like I assume is the case here, need "about 8mm of glass to encase it"? And why would the stress be any different with a thicker piece of glass than a thinner one?

[Dairy Queen]

A 3mm nugget requires about 8mm of glass to encase it. Two sheets of 3mm is not enough to encase without stress.

I'm not sure I understand this. Why would a 3mm piece of gold that's thin, like I assume is the case here, need "about 8mm of glass to encase it"? And why would the stress be any different with a thicker piece of glass than a thinner one?

What do you mean by thin? Is it 3mm X 1mm? I assumed it would be 3mm X 3mm.

If 3mm of gold is placed on 3mm of glass, it will not totally drop into the 3mm piece. It will, however drop into a 4mm or 6mm of glass.

Similarly, to encase the 3mm of gold in glass, 6mm is often not enough without stress. 8mm of glass is more able to encase the 3mm of gold without stress. There is a term for this principal, which I have forgotten.

[Dairy Queen]

The term has something to do with the balance of components.

[Brad Walker]

Similarly, to encase the 3mm of gold in glass, 6mm is often not enough without stress. 8mm of glass is more able to encase the 3mm of gold without stress.

No matter the thickness of the glass, you will still have stress. With thicker glass the stress may not be big enough to break the glass, but it's still there.

[Dairy Queen]

Similarly, to encase the 3mm of gold in glass, 6mm is often not enough without stress. 8mm of glass is more able to encase the 3mm of gold without stress.

No matter the thickness of the glass, you will still have stress. With thicker glass the stress may not be big enough to break the glass, but it's still there.

You are exactly right. I should have said less stress, or visible stress. This cold fog has me more confluent than usual.

Rose