I have been experimenting with both 1018 mild steel and rebar tie wire for my rings. While I like how the 1018 flattens, it work hardens too much and needs to be normalized more than the rebar. I also have trouble drifting my holes in the 1018 because it doesn't push the material aside in the overlap quite like the rebar does.

While rebar isn't exactly pure (or more or less pure) iron like bloomery iron, would people agree that it is a close approximation as far as softness, appearance and ductility? At the very least, would it be a superior approximation than 1018 steel? If so that I find it a bit ironic that the cheapest material would be the most historic...I know that ductility is desirable in mail so that the rings distort instead of break.

Other than Schmid, who draws his own wire from a bloomery, what do high level mailers typically use for their pieces?

Although most people seem to use rebar tie wire, I think it's foolhardy to suggest one type of wire to simulate all varieties used in medieval mail. Have you read Dr. A.R. Williams, The Manufacture of Mail in Medieval Europe: A Technical Note?
http://www.google.com/url?sa=t&rct=j&...7100,d.eWU

I just use mild steel but apparently bloomery iron is more ductile than anything we use today so I don't think there is a modern equivalent.

My best guess would be wrought iron, the trouble is it isn't really made any more, but there is still lots of it around.

Try looking for wires that are listed as "dead soft annealed" and "Drawing quality" many of them are made from 1008 or 1006. Not only are the drawing quality wires low carbon, they also have very low levels of manganese, that will help slow work hardening as well.

Also, the rebar tie wire, is not made from the same unknown junk as most rebar, it tends to be more similar to 1018 as it needs to be ductile enough to be twisted and still hold the bars together.

I found some 99.5 percent pure iron online, but it is very expensive (about 150 dollars for 10 meters of 16 gauge) and it seems to be intended for use by chemists.

Dan, I know that rebar is basically melted down scrap, but what is puddled iron?

http://en.wikipedia.org/wiki/Puddling_%28metallurgy%29

There is this place in the UK that re-use old makes new wrought iron. They even make wire, said so last time I asked them about it for a maille making project....

http://www.realwroughtiron.com/

They have puddle iron of course but also proper wrought.

I used to use what is sold over here as 'baling' wire, very soft and easy to use. Agricultural suppliers stocked it.