Investment

With a good model made, the next hurdle is getting a good burnout of the investment mold. And that requires the right investment. While traditional investments can be used for stone-in-place, they aren’t specifically tailored for it. Several investment powder manufacturers have developed investments specifically suited for the stone-in-place casting process, including Ransom & Randolph (“Solitaire”), SRS (“Stonecast”), Hoben (“Gemset”), and KerrLab (“Satin Cast Diamante”).  One of the most recent investments tailored to this technique is GemGuard from Neutec. Bell says that his company has been developing the product over the past two years.

“Stone-in-place limits the amount of finishing you can do,” Bell says. “More to the point, you want to minimize the amount of finishing you have to do because more finishing is more labor and more cost—and the idea of stone-in-place is to reduce cost. We set out to create an investment that would improve the as-cast surface that comes from stone-in-place casting.” According to Bell, the problem with traditional stone-in-place investments is that the majority of them are designed just to protect the stones. Which at first blush doesn’t sound like a problem. “Chemistry that’s aimed at protecting stones can be detrimental to the surface finish of the metal,” Bell says. “We were interested in protecting the stones, but wanted an improved as-cast finish as well. With this investment, we’re actually able to protect them at a higher temperature than we could previously (676°C/1,250°F versus 630°C/1,166°F) and that helps to get a better burnout. With that, we’re able to get better as-cast surfaces on the metal, which was our main intention.”

GemGuard is used like any other investment. It’s what’s inside that counts. “Ninety-eight percent of all investments are essentially the same,” Bell says. “It’s the two percent that’s proprietary that makes the difference.”