6 ms·

Once you've got the metal, how are you going to heat it up so that you can re-shape it?

mobiplayer 11y ago
That's an interesting question, however it is not what I was replying to. I'm not sure your question should be pointed at me :) In any case here's my quick answer: I hope they come off as Lego bricks.
eropple 11y ago
Why not wood? You can easily build wood fires hot enough to work refined aluminum (all those cans, good for something!), copper (rip out the plumbing and wires en masse, it won't be pure but it'll be close enough), tin, and zinc; with copper, tin, and zinc those you can create bronze and brass. Iron would be out of the question with simply a wood fire, but--assuming other knowledge was intact, of course--you could build a forced-draft charcoal burner which can easily get hot enough to melt down some forms of iron. When I started thinking about this problem I was expecting it to be a tough one, but I think it's achievable.
- abakker 11y ago
  Iron and Steel can be worked on a charcoal/wood fire. Maybe it won't be easy, but the scale of malleability is basically linear with temperature. Every 100 degrees and it gets a bit softer. Metallurgically, this won't necessarily yield the best parts if we can't reach critical temperatures - 1900°F, but even then, there are plenty of forgiving alloys out there, and plenty of metal that can be re-worked without melting it down. The bigger difficulty in my mind is having all the alloys identified. It is pretty business even with good modern tools.
- fleitz 11y ago
  Take your wood fire, add some aluminium you scavenged from an aircraft, then add some rust. Voila, 2500 C. http://en.wikipedia.org/wiki/Thermite http://en.wikipedia.org/wiki/Thermite
  - jnbiche 11y ago
    This should be a top-level comment. There are probably other similarly low-tech ideas that could be used to bootstrap a civilization.
panglott 11y ago
The problem with wood as a fuel is that any densifying human culture can burn it faster than it grows. Industrial uses compete with household uses for cooking fuel and heating. Europe in the 14th to 16th centuries saw massive deforestation in England, Germany, and elsewhere, and the state had to reserve stands of large timber as a military resource for shipbuilding. This was a significant concern in the early Tudor and Elizabethan era, for example, and the Black Forest reached its smallest extent during this time also, IIRC. Wood for fuel came from intensive coppice stands, and significant wood was imported as well. As the article says: "Wartime gasifier cars could achieve about 1.5 miles per kilogram [of wood]." Comparing the time it takes to grow a kg of wood versus the value of moving a car only 1.5 miles illustrates the problem pretty nicely. Wood is not a sustainable fuel for an industrial civilization, at anything like current rates of consumption.

That's an interesting question, however it is not what I was replying to. I'm not sure your question should be pointed at me :) In any case here's my quick answer: I hope they come off as Lego bricks.

eropple 11y ago

Why not wood? You can easily build wood fires hot enough to work refined aluminum (all those cans, good for something!), copper (rip out the plumbing and wires en masse, it won't be pure but it'll be close enough), tin, and zinc; with copper, tin, and zinc those you can create bronze and brass. Iron would be out of the question with simply a wood fire, but--assuming other knowledge was intact, of course--you could build a forced-draft charcoal burner which can easily get hot enough to melt down some forms of iron. When I started thinking about this problem I was expecting it to be a tough one, but I think it's achievable.

abakker 11y ago
Iron and Steel can be worked on a charcoal/wood fire. Maybe it won't be easy, but the scale of malleability is basically linear with temperature. Every 100 degrees and it gets a bit softer. Metallurgically, this won't necessarily yield the best parts if we can't reach critical temperatures - 1900°F, but even then, there are plenty of forgiving alloys out there, and plenty of metal that can be re-worked without melting it down. The bigger difficulty in my mind is having all the alloys identified. It is pretty business even with good modern tools.
fleitz 11y ago
Take your wood fire, add some aluminium you scavenged from an aircraft, then add some rust. Voila, 2500 C. http://en.wikipedia.org/wiki/Thermite http://en.wikipedia.org/wiki/Thermite
- jnbiche 11y ago
  This should be a top-level comment. There are probably other similarly low-tech ideas that could be used to bootstrap a civilization.

panglott 11y ago

The problem with wood as a fuel is that any densifying human culture can burn it faster than it grows. Industrial uses compete with household uses for cooking fuel and heating. Europe in the 14th to 16th centuries saw massive deforestation in England, Germany, and elsewhere, and the state had to reserve stands of large timber as a military resource for shipbuilding. This was a significant concern in the early Tudor and Elizabethan era, for example, and the Black Forest reached its smallest extent during this time also, IIRC. Wood for fuel came from intensive coppice stands, and significant wood was imported as well. As the article says: "Wartime gasifier cars could achieve about 1.5 miles per kilogram [of wood]." Comparing the time it takes to grow a kg of wood versus the value of moving a car only 1.5 miles illustrates the problem pretty nicely. Wood is not a sustainable fuel for an industrial civilization, at anything like current rates of consumption.