A friend of mine has been shooting a matchlock caliver for a while and seems to have the techniques down pat. He searched around for just the right slow match material and did a lot of research. He ended up buying hemp cord and braiding his own 3/8" match. You used to be able to find 3/8" braided hemp, but not lately.
He had tried braided cotton but it would fray out into a big dandelion head. Twisted rope was useless. What you want is the end of the match to look like a glowing cone. His hand braided line did that.
He tried soaking it in saltpeter but found that it spat sparks. He was worried about accidental ignition and ditched that. The best treatment he found (from 17th century texts) was to soak the braided cord in vinegar to leach out the lignin from the hemp. That made it burn hotter. He'd rinse it in water and then soak it in a baking soda solution to neutralize the acid and then rinse again. Then he would air dry it. He can light it with flint, steel, and charcloth and it glows nicely.
I'd recommend doing a web search for hemp cord and see if you can find someone who is still selling the 3/8" stuff. If not, get some finer cord and braid your own. You might try this stuff, although at 5.6mm it's a bit small:
http://www.rawganique.com/Dept-Hemp-Accessories/hemp-braided-cords.htmHave fun and don't underestimate the matchlock. My friend holds his own with the flinters.
