polyoxymethylene
polyoxymethylene a hard engineering thermoplastic used for making precision parts consumer products electronics and industrial products characterized by its nearly invisible flame and irritating formaldehyde odor when burned
because polyoxymethylene burns with a nearly invisible flame my friend did not realize a piece of polyoxymethylene caught fire under his cars dash his eyes where burning so bad from the fumes he could not see hes lucky he did not have an accident