The shrinking sounds like a very interesting way to go, I will need to test that and see how it works. I want to keep the stone looking natural, not all chipped up like some that I have seen.
Thanks
Pat

At this time I do not have a sketch, just starting in that direction. Will post one soon. What do you mean by "copper chill bars"? Welding will be either mig or tig depending on what I can put my hands on.
Thanks

Pat

You can use copper to help you do things like pull heat out of or away from an area.Copper bars laid along side strap to be welded will pull the heat away from the edge of the weld and help form the edge so the stone will be less likely to spall from the heat of the weld arc.
Likewise a thin copper sheet can be used to guard an area of a wood or stone piece to minimize damage.Just be sure to not direct the arc full onto the thin piece of copper and burn through it.
Just as you would not want to pull a stone from a stream and place it around your fire(it may well explode due to trapped water) you will want to be sure your rocks are as free of moisture as possible.I usually keep stones for future projects first near my wood stove in winter and then on top of the stove to drive off all the moisture.A dry stone is much less likely to crack,flake or even explode.
I use native granite,basalt,unakite and some other stones to good effect.I have less luck with stones like quartz and feldspar as these seem to be more sensitive to localized heat and will crack and chip if not heated evenly.
Local geologists can be a big help on things like this.

In theory there is no difference between theory and practice.
In practice there is.

The copper sound like a good way to go. I did not think of the stone needing to be dry, but here in So Cal won’t take long to get them that way.
Thanks for all the info.
Pat

Pat,

When Daedalus talks about "dry" regarding those rocks, he means more than just dry on the surface - they need to be dry all the way through. It's best if you can bake them in the oven first at about 225-250F for an hour per inch of radial thickness. That will drive out all the free water, though it won't get rid of the chemical water, if any. That doesn't go away until you reach 550-600F. Getting rid of the chemical water really only matters for things like calcining plaster or investment, but for welding around a rock you need to be sure the free water is gone completely so you can generate a steam explosion that may spall off pieces of rock.

Rich

The older I get the more I forget it seams. I should have thought about the water in the rocks for around my shop in Ramona CA after all the fires we had a lot of the rocks split/cleav and I would not want to be close when that happens. (Although we did get some great thin slabs for art work.)

Thanks
Pat