I have had more difficulty lighting Wetfire cubes by spark than cotton balls and PJ. Sometimes, even when crumbled, they do not seem to take a spark. I have never tried to light an Esbit cube with a spark, will it work or do you need a flame? I have tried other items such as the grill starters, and they all needed a flame, I could not light them with a spark. I generally carry a combination of cotton and PJ, dry cotton balls, a tube of petroleum based lip balm and Wetfire tinder. Only a small amount of each, but together, I think it should work in most conditions. These along with a Blast Match or the new Sparkie, some REI or UCO storm proof matches and a cigarette lighter and I should be ready for everything except the Antarctic and Mount Everest (because neither have any wood to burn).

I have used wax based lip balms on cotton as well, and they work, with the same cautions as the PJ, do not over saturate.