I had a few bars that were about 7-10 years old. I tried lighting them with a BSA hot spark, they wouldn't light. It took a few seconds with a lighter before I got one to catch, when it did catch it wasn't giving off a lot of heat. I found it to be about as hard to light as an Esbit tab, but not as hot. My experience with them wasn't very good. I have had great luck with fatwood and cotten/vaseline though. The cotten catches really well and burns for a long time, if it gets wet I just wring it out. Fatwood burns well even when wet and makes a nice hot flame, I can even light it with a hot spark if I scrape a bit off.