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I found a short discussion in the old archive in which Brock Craig says a mold made of Hydrostone can be used immediately. Am I correct in interpreting that to mean the mold doesn't need to dry before firing. Also Is this material suited for both open-faced molds and for lost wax molds?
Thanks

Not Hydrostone, Hydroperm. I've only used it for open face casting. It has specific mixing criteria, which when done correctly leaves the mold full of small bubbles, similar to an Aero chocolate bar. This network of bubbles allows the moisture in the mold to be vented through the mold. No 3 day air drying, no pre-firing, just cast and use. Brock

Aero chocolate bar?

must be a Canadian thing....

smartiepants

Brock wrote:Not Hydrostone, Hydroperm. I've only used it for open face casting. It has specific mixing criteria, which when done correctly leaves the mold full of small bubbles, similar to an Aero chocolate bar. This network of bubbles allows the moisture in the mold to be vented through the mold. No 3 day air drying, no pre-firing, just cast and use. Brock

Lundstrom in Book 3 "Glass Casting and Mold Making" gives detailed directions. Basically, you make a stiff neoprene rubber disc and attach it to a drill extension. You mix by moving the rubber and drill extension attached to your heavy duty spinnng drill up and down in the bucket of wet hydroperm.

I got the mixing thing down OK, but it is hard to get a nice surface with no bubbles. you have to do a skim coat first with no bubbles.

Bert

Is that skim coat hydroperm that hasn't been whipped up with the electric mixer? So then the mold doesn't need another kiln wash or other separator?

There is a mix sold that is called Merlin’s Mold Mix. There is no extended drying time. I’ve never used it, so I can’t tell you how it works, but I’ve been told that it does well and can be fired repeatedly. I’ve seen it in L.A. at Pacific Art Glass. They sell it in 10# and 50# bags. You need to call them for the price, 800-354-5277.

Rob