Hi, Quite a while ago I read about someone using carbon felt in their Optimus 111 spirit cup as a wick and it sounded like a good idea so I purchased some from China (via fleabay). However anything involving high temperature resistance and China, I am always mindful their love of using asbestos in everything.(like using it for string in those sky lanterns!). The felt was pretty fibrous and I cut it up outside as it made quite a lot of mess - it was good however, it definitely helped regulate it burning and now primes with quite a lot less meths. Still I wasn't entirely happy they hadn't just mixed together asbestos, carbon black and other bits to make something resembling carbon felt. Anyway I took some into work and someone kindly took some samples (small circular bits in plastic bag) and used a portable XRF on it. I thought the results may be of interest to anyone here who has wondered the same.... Note , 'LE' in result table means, bottom, 'light element' , i.e. whats red highlight in periodic table below - which in this case is pretty much Carbon. So in conclusion she thought it probably was mostly carbon (~88%) and not asbestos. I tried to find any results of what 'known' carbon felt was composed of but couldn't - if any Chemists read this I would be interested to know what they think!