Lots of cool stuff there, and many people with opinions on how to refinish a cast iron pan, and a lot of cast aluminum, but precious few on how to smelt and cast carbon steel or large (20 kilos or more) bronze pieces.
Mostly I’ll be drawing on shop class (greensand and aluminum) and art class (lost wax silver) from WAY back for personal experience, and documentaries like those that are trying to recreate wootz and the Ulfberht viking swords. But if anyone wants to chime in with a possible source, reference, or personal experience, I’d love to hear it.
Tim sent me the link to your page, and I just took a quick look. You say you found “precious few on how to smelt and cast carbon steel or large (20 kilos or more) bronze pieces.” I’ve only done pewter casting a little bit of brass, but I can tell you that casting steel and making large castings are both dammed difficult!
Cast iron is relatively easy, because cast iron contains about 2% carbon, which lowers the melting point. People in Asia have been using cast iron for thousands of years. Casting *steel* is another matter. Steel has a higher melting point, but the real tricky part is that the steel must be kept separate from the fire, or it will exchange carbon with the fire and tend toward either cast iron (high carbon) or wrought iron (low carbon). The steel must be melting in an enclosed crucible to prevent this. Such crucible steel has been made it the mideast/east for over a thousand years, but I am not aware of it being cast. More typically, it was allowed to cool in the crucible and the ingot of steel was then forged to shape.
Making large casting is difficult simply because of the scale involved. You need a big fire, a big furnace to contain the heat, a big crucible to hold the molten metal, a big mold, and some way of lifting and tilting the crucible to pour the metal into the mold. In medieval times they would sometimes melt the metal in the bottom of the furnace, and then poke a hole in the bottom to allow the molten metal to run out into a mold that was positioned below the furnace. So it is definitely doable, just difficult.
Hope this helped! Feel free to contact me if you need more info.
Reply sent via email. If you don’t get it soon, let me know.
Lindsay Publications used to be a great source for reprints of old books about many things, including casting. The owner retired a few years ago but the business continues under another name, I believe.
Look for the works of David Gingery; he wrote a series of books about casting aluminum in your back yard, with a simple furnace that burns plain old grill charcoal. That doesn’t get you to steel, though that too can be done at home (it’s just harder and a bit more dangerous).
Yes, I’ve seen those before. But it’s like the scene with Allonia talking communication – there’s all the “facts,” then there is how it would appear to an informed observer that the writer really has a clue about the subject by implying as much as is actually said. For example, I know that iron and steel melt at a higher temperature than aluminum, but does that have a noticeable effect on the condition or type of greensand used, or what you have to do to reuse it? Can you make a decent carbon steel if the crucible is sealed in the furnace, pulled, opened, and poured, or does it have to solidify more slowly in the crucible while still sealed to avoid picking up to much carbon from the charcoal? When casting a hundred-pound daggerboard for a sailboat keel, would it be best to pour it flat or vertically, or does it make no difference?
Basically I’ve got a scenario, and I’d like to make sure it’s reasonably accurate by running it by someone knowledgeable without actually having to set up a furnace in my back yard and try it (which, while neat, would be moderately expensive, time consuming, and potentially dangerous).
My step-brother has been doing primitive smelting and ironmongery for the last few years. He’s an SCA guy, chemistry PhD, and really smart. If you are interested, I’d be happy to put you in touch.
Otherwise, you might try asking around your local SCA crew for the blacksmiths.
Yes, that would be wonderful. If he’d be willing to read through a bit of the story, he could tell me if I’m close enough that a few tweaks will make it totally accurate, or if a whole-sale re-write is needed, or maybe just a little more of the “background assumptions” need to be made more clear. What I’d like is a “reasonably” representation of the problems and possibilities of such an endeavor.
I’ve sent him this page, and he should be pinging you shortly. I’ll be very interested in hearing how it goes!