A Ulrich Bretscher provides this 1668 matchcord advice: the musketeers used a tightly twisted hemp or flax cord, which they boiled in a pot, filled with ash and water.(They didn't filtrate the ash residue before boiling).Then the match was thoroughly rinsed with plenty of water and dried . . . match was always made from flax or hemp, though nowadays, there are some modern musketeers who make matches from cotton. But cotton never yields a good match, - it burns with too little ember.
The reason for boiling in potassium carbonate (pot ash = wood ash) is to remove the lignin from the cellulose of hemp or flax. In some detail the explanation given is:
Raw textile fibers contain a lot of lignin. Plants need this brown colored lignin as a glue to bond its cellulose fibers. But you, as a musketeer, have to get rid of this lignin, since it produces most of a cord's ash.
If the match, used in a match lock musket, produces a lot of ash, this ash may drop in the open priming pan while aiming and then ignite the gun involuntarily. So watch out, always blow off the ash from the match before opening the pan of your musket! Even a bucked match yields some ashFor bucking a rope, you boil it in a potash solution which dissolves the lignin. Common ash, e.g. from your fire place, contains about 10% potash (potassium carbonate, K2CO3) by weight. It is very alkaline. But you may buy the potash in a drugstore, too. By the way, the meaning of "bucking" is to boil a textile in a bucket (German: beuchen)
Years ago I made a sear-lock, Italian style, rifled barrel. Shot fine. But I had soaked my coton rope in saltpeter, not the thing to do or so I now learn.