Its been a slow (match) day

One of the things I have started to do as part of my re-enactment hobby is make the slow match for the musket block I'm a member of (see it wasn't a post about cricket at all).  It's a vital item for a matchlock musketeer who will go through at least a meter of the stuff at every reenactment weekend.  Of course you can buy it, but its easy and quick to make your own, it saves money and you can't always get the stuff when you need it.

Back in the seventeenth century soldiers on campaign would steal, er I mean requisition, the cords that criss crossed bed frames to hold up the mattress to make match cord with, so after they passed through town you would be sleeping on the floor until you could get more rope.  Saltpetre was a little more difficult to source with original recipes using dissolved black powder, or ash and lye or even boiling down urine to obtain it.  In fact human urine was such a good source it was collected on an industrial scale from alehouses, private homes and even by stealing the contents of cesspits! Poorer people would sell their urine as a source of income, provided they weren't so poor that they didn't have a pot to piss in!

For me it's a easier and a lot less smelly!  The commonest source for the cord is 100% jute sash window cord in either 6mm or 8mm diameter.  Easily obtained online (pun not intended).  I tend to buy from a firm called P T Winchester Ltd as I can be sure it doesn't have a nylon core.  Saltpetre is Potassium Nitrate (KnO3) and is sold as lawn food, stump remover or (in food grade quality) for curing bacon or hams.  Again the internet is your friend here.  I look for something that is as pure as possible assay at 99% pure if I can get it, which I usually can.

Making the slow match is simple.  Add 4 or 5 litres of cold water to a bucket and stir in 4 - 6 Tablespoons of saltpetre per litre.  Throw in the sash cord (if it was in a hank unroll it first) and weigh it down to ensure it is submerged.  Leave it for 12 - 24 hours.  Lastly take it out and lay it out flat to dry.  This last part is important, as it ensure that the saltpetre is evenly distributed.  Once it is dry you have your slow match.  Don't throw away the unused solution.  It doesn't go off and can be topped up to replace the bit soaked up by the cord and used again.  With sash cord at about £50 per 100 metres and saltpetre at about £12 a kilo I reckon that even without recycling the saltpetre solution it is costing less than 60p a metre (not counting the cost of the bucket!) for the finished matchcord.

The exact amount of saltpetre to use can be found by trial and error, sometimes you get slower match than other batches, sometimes faster.  I prefer to err on the side of faster as at least I know it will burn.  What you are aiming for is a burn rate of about 1-2 cm a minute without it spitting.  Spitting is a sign of too much saltpetre so if that occurs with the lit cord all you do when you top up the solution for the next batch is add more water and less saltpetre to the replacement solution.