Hi all, I have recently become very interested in the idea of metal casting after having shaped a ring from a small bit of silver. The shaping process had nothing to do with casting at all, but the idea of being able to create unique, personal metal designs is very interesting to me. I had hoped to learn to cast with silver, but after learning that the demands of that metal are beyond my current skills and budget, I settled on starting with pewter. I haven't bought anything yet because there are some bits of the process I still don't really understand.
First, the mold. I'm finding it hard to pick out a good molding material for molten pewter. Most silicone seems to only be able to handle about 400 deg F maximum, and pewter can reach up to 650 deg F for casting temps from what I understand. Can anyone recommend a specific type of inexpensive rubber or plaster-esque material to use? I found a compound called Quick-Sil on a few sites--it looks promising, but I can't find anyone with experience using it.
When making a two-part mold, how exactly can I ensure that it's properly ventilated? None of the tutorials or guides I've read have said anything at all about ventilation, but when reading forums, I notice people often have problems with pock-marks on their casts, the response to which is usually "you need better ventilation." How, besides poking little holes in it that would cause spikes to protrude from my cast?
I've also gathered that heating the mold before pouring helps a fair bit too. I see how you could manage this with sand or metal molds, but I'm not clear if this suggestion applies to silicone. Does it?
And finally! the sprue. Man, I've seen this word about a million times, and not one single website or forum post I've seen has explained what a sprue is. I've gathered that it's just a stick of sorts stuck onto a "top," with the bottom stuck to your original. But I don't know if any kind of special wax is required to make one, or if it's even made of wax at all, or what. Besides that, I'm unsure about how to make a funnel-like top in a two-part mold. The few sites I've seen shape a reversed mound in the clay, so the silicone flows over it to make a funnel. The interesting part is that, while this would work great for one side, I don't know how one might go about making the other side of the mold. If you just flip it and fill, obviously the silicone would fill both the key holes and the funnel top. That would be bad, methinks. What am I missing?
Some of these are probably stupid questions, but information on this craft is spread very thin and far between. It's confusing. Answers to any of the above, or any other general tips for working with pewter, would be greatly appreciated. (I already know to use a pot.
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) Thanks for the tip, I don't suppose you know of an online supplier that sells hobbyist quantities?
