Black match

Lengths of black match

Black match, also known as bare match, is a simple fuse that is regularly used in pyrotechnics, is very easily ignited and typically burns about 1 inch (2.5 cm) per second, depending on the quality of the black powder used. Commercially it is used almost exclusively for the manufacture of quick match or in priming. However in some hobbyist circles it is commonly used as a fuse for igniting entire pyrotechnic devices. Black match is made by coating a thread or threads with a slurry consisting of Black powder, a solvent and a binder, with the solvent usually but not exclusively being water (with or without a fraction of alcohol added). Dextrin is the most commonly used binder in the hobby firework world, with Gum Arabic being less frequently used but superior, with many less issues with flexibility and crumbling. When using black match one must consider the potentially unreliably burn rate and the possibility of sparks from other devices igniting it.

[edit] Tutorial

Composition

Tools and materials

Tools
Plastic mixing cups, digital scales, mixing sticks--paddle pop sticks are fine, isopropyl alcohol, plastic spoons, spray bottle, small plastic container and 1/8" (3 mm) drill bit. You will also require standard cotton string that needs to absorb moisture easily (i.e. the black powder slurry). Do not use cooking twine, nylon string etc. It needs to be thick enough to slide through the 1/8" hole we are going to drill in the plastic container lid.

Measuring out ingredients

Method
Carefully weigh the meal and dextrin powders into the plastic cups and set them aside. The reason why you should weigh them separately is, if you add too much of an ingredient it is easily adjustable. Dextrin acts as a binder and when the composition dries the black powder will harden making the black powder covered string harden. Now measure out a ratio of 1:4 of isopropyl alcohol and water (ie. 10 ml of isopropyl alcohol and 40 ml of water), if you use more alcohol the dextrin will lose it's adhesive properties. Pour this into your spray bottle. You don't have to use a spray bottle, you can use a small mist pump or manually spoon small amounts of the solution into the mix, the choice is yours.

Screening together the two powders

Now mix both the meal powder and dextrin together and blend using the screen method until the mixture is homogeneous.

Drilling hole in lid through which string will be pulled

With your small plastic container, drill a 1/8" (3 mm) hole into the center of the lid. Do this by placing the lid on a scrap piece of wood for support and slowly drill the hole. Make sure the hole is clean and has no burrs, if there are remove them.

Feeding string through the hole in the lid

Prepare your string by cutting it into approximately 30-40 cm lengths (12" - 16"). This is a convenient length to work with and provides long enough fuses for most purposes but longer or shorter lengths may of course be used. Take one length and thread it through the hole about 2-3 cm (3/4" - 1").

Spraying the solution

We now need to prepare the black powder slurry. Using your spray bottle add a small amount of solution we prepared into the composition and mix together. Continue adding the solution until you achieve a slurry paste (consistency of yogurt). The alcohol reduces the surface tension in the mixture and makes the water actually "wetter". When the string is pushed into the black powder slurry, it will absorb quickly into the cotton string, much faster than it would with just plain water. Empty the slurry into the plastic container.

Mixing the string into the slurry

Take the lid and feed the string into the slurry, taking care not to tangle it. Using a mixing stick submerge the string in the slurry making sure it is completely covered and attach the lid. You will need to let the string sit in the slurry for about 1 minute. This will allow the string to absorb the mixture deep into the fibers. Dampening the mix also dissolves the potassium nitrate and this will be easily absorbed into the pores of the charcoal, making the black match burn better.

Pulling sting through the lid

Place one hand on the plastic container and take hold of the string. Carefully pull the string out of the hole. It will now have a nice even coat of black powder slurry. Attach the string to a board or clothes hanger with a peg and allow drying time of a few days. Although it may appear to dry in about a day, it will actually take several days to completely dry and become usable.

Dried black match

Simply repeat the process again with a new piece of string, you will need to add more solution to your slurry as the string will absorb the moisture and make the slurry dry. Once your black match is completely dry (it will be rigid) cut it to your desired lengths.

[edit] Video

Black match - 722kb - A 15 second example demonstrating a black match burning. The rate at which the black match will burn depends greatly on the quality of your black powder. If you use high quality black powder your black match will burn very quickly.