High Detail Permenant mold

[Burningleon]

Hey guys. I've got a question for you. I recently an insignia out of clay that I need a few copies of. The insignia has several small details in it but is relatively two dimensional you could say. Is the kind of piece I could flip upside down and press into some sand to make a mold of it. However the sand isn't picking up all the finer details I sculpted and I'd prefer no to try and spend hours with a dremel trying to get these details to show back up. I'd be casting it out of aluminum by the way. Any ideas on some kind of ceramic or plaster i could coat my sculpting with then remove so that I could pour a mold of it? The cheapest solution would be the preferred one as the goal is to make money off of these insignias. If I need to pour multiple molds because they'd have to be destroyed then I could do that if it would be cheaper than trying to make a permanent reusable one.

Any ideas and suggestions would be appreciated as I've only sand casted before. I've never tried lost wax or anything like that. Thanks for the help guys.

[RomanLini]

Google or search the forum for "jewelry casting techniques" I think that will be your best option.

It probably involves making a rubber negative mold from your positive master.

Then cast wax positives in the rubber mold, and use those wax positives to make high detail molds in heat proof plaster. The wax enables you to make a high detail mold then melt the wax out without damaging the mold detail.

Then obviously cast metal in the plaster mold and destroy the mold to release the metal.

Another option would be to machine a female mold direct from steel, provided it has no undercuts. The cast a lower temperature metal product in the re-usable steel mold. But that requires a lot more mold costs and your clay master is not able to be used.

[Rocco85]

Google something called "Delft clay". It's sort of the same concept as sand casting but with a much finer mold material that allows for a much finer level of detail, it might give you what you're looking for.

[Burningleon]

Do you have a brand recommendation for the Rubber mold and the Plaster mold?

[RomanLini]

The rubber mold materials are available from "urethane casting" suppliers.

As for the plaster mold it depends on the temperature of your product metal. I have heard people used plaster of paris (very well dried) for lower temperature jewellery metals like silver. Plaster can hold a very fine detail.

As for higher temperature metals I don't have enough knowlege to offer suggestions on mold materials sorry.

[awerby]

to pour metal into. The plaster is a binder; you need to add a refractory aggregate like silica flour (about 2 parts by volume to each part plaster) to make something that will stand up to the burn-out (not melt-out - you need to get to about 1200F). This makes a mold that can only be used once.

If you're sand-casting aluminum, the detail is limited by the fineness of the sand. If you're using 30-grit, you might try a finer mesh. Petro-bond is one brand available in the US; it gets good detail, but not as good as investment casting.

For little medallions, you might think about casting pewter instead. The metal's more expensive than aluminum, but it's a lot easier to work with. You can pour it straight into a rubber mold, and reuse the mold up to 100 times or so. You'll get better detail this way than with any sand-casting process.

Andrew Werby
United Artworks- Sculpture, Jewelry, Furniture,and other Art Objects, plus Art Resources, Techniques of Sculpture, Jewelry and Lapidary, an Online Bookstore, and a Custom Art Referral Network