Casting bronze with Glass

[imraslan]

I am wondering if it is possible to cast bronze with glass for a bracelet jewelry project that I am working at. Will they stick together if I want to make the middle part from bronze and the sides in glass? Please let me know if anyone has any experience with that

[Ron Reichs]

From the lack of replies, I would guess that nobody has tried it yet.
I certainly haven't been brave enough to, although I cast both glass and bronze but not together.
The coefficient of thermal expansion of each material is vastly different & my guess is that on cooling the stress set up would cause the weaker element (glass) to crack.
The melting temerature of each material is also very different. I pour my bronze @ 1125c & with my Gaffer crystal my soak temperature is 830c
My suggestion is: cast the bronze component first & then fuse the glass into it.
The safest way is to glue the glass component to the bronze.
I am about to post a picture of my latest effort which incorporates glass, wood & bronze.
Good luck with your experiments. I would be fascinated to know if they work.
Cheers,
Ron

[Brock]

I have a vague memory about a Steve Tobin show from years ago involving bronze and glass.
I remember discussing it with someone then, but couldn't find anything in a quick search.
It is worth a look at his website: http://www.stevetobin.com/home.html

[Valerie Adams]

Depending on the complexity of your project, perhaps some of the new(ish) PMC clays would work for you. I know they now have a bronze clay.
Here's a blog post about glass and copper clay, which might help:
http://artinsilver.com/blog/2009/06/26/ ... etal-clay/

[Morganica]

I think it's worth a try but I'm not sure I'd hold out much hope of it working. I've cast glass components for bronze sculptors, and we always cast the materials separately and either glue together or fasten mechanically.

As Ron points out, bronze has a much higher melting point and typically uses different refractories (although you can use those refractories for glass). If you heat glass to bronze melting temperatures you'll be changing the glass chemistry and that could cause problems--one or more colors of glass could turn incompatible and cause cracking within the glass. There's a good chance your refractory won't hold up to the higher heat, either. And if you fire cooler, at glass temperatures, well...I believe silicon bronze has almost twice the thermal expansion of the glass. It will be (greatly) expanding and contracting around the glass and liable to crack.

People like David Bennett blow glass into bronze (and there's a very cool series of process shots for that at http://epiphanyglass.com/cool-stuff/vis ... s/bennett/), but the glass is relatively thin and not exposed to prolonged processing temps or annealing you'd get with casting. He's also blowing into, not over.

It would be interesting to try the bronze PMC and see how those work together; the process temperatures are closer (1550F for bronze clay). You'll still probably have the expansion/contraction issues, and bronze clay must be fired in a reducing atmosphere, i.e., oxygen-starved, by embedding it in an activated charcoal bed. Not sure what, if anything, that would do to the glass.

[imraslan]

Thank you for all the replies, I will try checking the links and update you of the outcome of the project

[tonyroberts]

I've seen a glass casting by Keith Cummings which appeared to be glass with a very high metal content, enough to enable the metal content to be polished. He has examples and a general discussion in his book 'Techniques of Kiln-formed Glass' (pages 95-98).

I've long included bronze in my cast stained glass, along with brass, copper, chrome, silver, and other metals, even stainless steel. The general idea is to minimise contact between the metal and the glass. Mixing powdered metal with powdered clear glass is one method - the proportion needs to be 1:100 or less for best results, but you can go as high as 1:10. If you need to embed solid metal, then use woven or mesh to reduce contact. I sometimes very lightly dust the metal to be embedded with an appropriate separator (I use talc on stainless steel, for instance), again to reduce contact and to allow the metal to absorb the stress rather than let it affect the glass.

Experiment! Think carefully about what's happening within the piece and make allowances. Don't take 'can't be done' as the end of the matter...

Tony

PS - look on my website for lots of metal staining/inclusions for ideas: http://www.tony-roberts.com

[Alexis Dinno]

I've seen a glass casting by Keith Cummings which appeared to be glass with a very high metal content, enough to enable the metal content to be polished. He has examples and a general discussion in his book 'Techniques of Kiln-formed Glass' (pages 95-98).

The iridescence on the piece in the below photograph results from bronze. The finished piece is quite metalic on one side. Caveat: try not to let the metal touch mold-surfaces as this tarnishes the look.