Wow. That's the kind of response that makes this group famous. Thanks to everyone for their tips, especially those of you who have taken the time to put together carefully illustrated guides to help newbies.
First off, I figure I should clarify a mistake, since we've now done some more of our homework.
Paul Revere did not use sand casting to make bells, although we think he did do sand casting. I'll check up on that and report back. The technique was a variation of the lost-wax method. I'll give you the authoritative statement on it: "Bell makers first created an inner 'core' that modeled the inside diameter of the bell. They accomplished this by digging a hole in the ground, building a hollow pile of bricks in the center, covering them in a special mud, and using a pattern to pack the mud into the shape of the interior of the bell. Second they applied a mixture of tallow and wax to the outside of the core, creating a perfect wax model of the bell. Workmen added any lettering or designs to the wax at this point... Third, workers applied numberous thick coatings of 'bell mud' on top of the wax, creating the 'shell,' which was a model of the outer surface of the bell. When the shell hardened, a workman lit a fire inside the hollow brick structure at the center of the core, which melted the wax and allowed it to drain off, hardening the core in the process.... The shell was then hardened with additional fire, and covered in sand or loose soil to prevent it from bursting. Finally, molten metal was poured into the space between the core and the shell."
- from "Paul Revere's Metallurgical Ride: Craft and Proto-Industry in Early America" by Dr. Robert Martello, which happens to be the Ph.D. dissertation of one of our teachers for the course. (Yeah, good thing we found that.)
Also, we took a look at a translation of De Pirotechnia, which was conveniently located in the reserve section of the library. It's pretty interesting, but really long. So, we have one person reading that and reporting back. I think I got the better end of the deal by offering to post to the newsgroup.
As far as the actual casting is concerned, in the interest of time, we've decided to order some Petrobond. Fortunately, we already have some lying around (but not enough to cast the bells), so we're going to try casting white metal on Tuesday. The MatSci professor has some experience with this, so combined with what we've read, we think we can do it without hurting ourselves.
We still have a good deal to work on, and I'll probably be back with more questions about molding shortly.
Thanks again,
Eric Gallimore