For backpacking, the lightest and one of the most reliable is the aforementioned vasoline cotton balls. Store them in anything waterproof. Ziplock freezer bags work great and they're very light weight. The trick, though, is the amount of vasoline. Vasoline doesn't burn, it melts. You can't light it with a match. You want it to nicely coat the outside of the cotton but be sure to keep the inside of the ball dry. To use it, pull it apart and the dry inside will light instantly with a spark. As the vasoline heats, it evaporates and the gas is what burns for 10 to 15 min. Usually 1 or 2 strikes from a striker is all it takes to get one going.
When I was just learning the tricks, I once tried to melt vasoline and soak it into the cotton. The cotton sucked it in immediately and thoroughly soaked the inside. You couldn't start those things with a blow torch.
The easiest way I've found to make them is to put a dozen or so balls in a ziplock bag, add a big dollup of vasoline, and knead them while watching TV. It takes a little practice to learn how much vasoline to use. Oh - make sure the balls are real cotton. They'll have a cotton ball symbol on the bag. Some are made from synthetics and it won't burn nearly as well as real cotton. Walmart sells them in jumbo size. Those will burn extra long.
A buddy of mine comes out to the range one day and opens a Nalgine bottle full of water, pours out the contents on the concrete and I see a ferro rod and cotton ball. He pulled the cotton ball apart and on the first strike, it ignited and burnt for about 10 minutes. According to him, you need to soak the entire cotton ball and it won't matter if it gets wet.
I know a dry cottonball won't hardly light at all with a striker for me.
