“…However, locally accelerated oxidation may take place in the presence of impurities and large structural defects. This process, known as pitting, has been reported on CFs under liquid or gaseous oxidative conditions, such as electrolyte 51 and acid treatments, 52,53 thermogravimetric analysis (TGA), 11,26,32,54–56 plasma etching, 22,52 as well as using tube furnaces, 32,57 flow tube reactors, 58,59 air‐filled ovens, 11,30 environmental electron microscopes, 60 and other heated processing systems 33 . Under open flame attack, exacerbated pitting was observed on CF bundles after exposures of a few minutes to CH 4 ‐based flames 61 .…”