When you’re desperate to start a fire, desperate means might be needed. I would not recommend this for your “everyday” tinder, but only as your last resource, when you have to get a fire started but nothing else will work. These will burn for about 3-1/2 minutes, at a temperature of over 3000oF, which make them ideal for situations when you can’t find dry kindling or fuel for your fire.
Black powder is used for this type of tinder, as it burns readily, but not as quickly as modern gunpowder. To make it, put about two tablespoons of black powder into a glass or ceramic bowl (don’t use plastic) and cover it with nail polish remover. Please note that the nail polish remover you choose must be a type which contains acetone, or this won’t work. With your hands, work the gunpowder and nail polish remover into putty. Don’t worry, the mixture won’t do more than dry out your skin.
The putty must be kneaded for a while, so that it forms multiple layers, much like Damascus steel is a number of layers. This is done by flattening the putty and folding it over multiple times. These layers are what control the burn rate, keeping the tinder from burning too rapidly.
Finished black powder fire starters are good as long as they are damp. Once they dry out, they are no longer usable and can actually be dangerous to try and use. How long they keep will depend upon how airtight the container you keep them in is.