Jack Hirsch Posted February 19, 2023 Share Posted February 19, 2023 Hello everyone, while researching permanent molds as I want to repeatedly cast the same thing. While researching I ended up finding a few formulas in Volume #2 of The Chemical Formulary and they look good, but I feel like they would only survive one maybe to cast, not be "permanent" like the formulas suggest. I'm still going to try them out I just wanted to see what you guys thought of them first. Formula #1: 3 Part by weight Chromite 1 Part Fused Silica 1 Part Bentonite Formula #2: 100 Parts Ground Soapstone 15 parts Sodium Silicate 25 parts water Quote Link to comment Share on other sites More sharing options...
George N. M. Posted February 19, 2023 Share Posted February 19, 2023 I'll just mention that in Formula #2 ground saopstone is talc. The concern with that is that talc often has asbestos as an accessory mineral. That is why finely ground corn starch has mostly replaced mineral talcum powder. So, big red flag for really good inhalation protection if you are grinding your own soapstone. I wouldn't be too concerned about the varieties that are sold for carving (I have bought it at Hobby Lobby) but I would be more careful if I were grinding up drops of soapstone sinks or counters. Also, the bentonite in Formula #1 might be somewhat of an issue because it swells when wet and contracts as it dries. I don't think that would be a good quality in a mold. "By hammer and hand all arts do stand." Quote Link to comment Share on other sites More sharing options...
Jack Hirsch Posted February 19, 2023 Author Share Posted February 19, 2023 Thank you, I was aware that it was talc, but completely forgot that it was carcinogenic. Figured I would do it outside with a respirator just to be safe. I know soapstone-carved molds are a thing, so I'm wondering if this would actually work moderately well. Quote Link to comment Share on other sites More sharing options...
Scott NC Posted February 19, 2023 Share Posted February 19, 2023 Have you looked up chromite sand? It's evidently used in the foundry industry these days. I don't know about it contributing to permanancey of your molds though. I might have to get a copy of that book you have, just for fun. Chromite is a bit of a rabbit hole. It led me to chromium, then hexavalent chromium and all over the place. I would do a lot of research on these things, just for safety and piece of mind. Quote Link to comment Share on other sites More sharing options...
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