because there was a gas that was put into the balls during manufacturing that burns really well but to be clear it's just ordinary air in there it's the actual material of the balls which is called celluloid that burns really well until about NUMBER_TOKEN ping pong balls were still being made of that stuff since it's a light and durable plastic that gave the balls the right properties for being whacked about although it has a high flash point of over NUMBER_TOKEN degrees celsius once celluloid hits that point it can start burning without needing a spark or flame to get started and it burns really easily celluloid gets its ignitable properties from a substance called nitrocellulose which was used as a replacement for gunpowder and weapons during the NUMBER_TOKENs by the middle of the century american entrepreneurs discovered that dipping nitrocellulose in wax turned it into a hard enduring substance and patented it as celluloid which was one of the first manufactured plastics celluloid enjoyed a long stint in lots of applications famously including rolls of film like the kind used in projectors unfortunately when the lamp and the projectors got hot they had the tendency to make the celluloid film dramatically burst into flames because of its flammable tendencies celluloid fell out of use in most cases though ping pong balls were the exception until NUMBER_TOKEN when they started to be phased out because of the fire risks of transporting lots of balls around but older ping-pong balls are still made of celluloid so you probably want to keep them away from any sources of flame and celluloid hasn't totally disappeared either it's still used to make amongst other things guitar picks but thankfully as far as we know there haven't been any unintentional fires caused by guitar picks so for now there's nothing to fret about thanks for watching this episode of scishow if you enjoyed it you might enjoy becoming a member of our channel channel members can submit questions to our qq inbox or see exclusive behind the scenes photos if you're interested you can get started by clicking the join button below this video
START_SELFPROMO_TOKEN thanks for watching this episode of scishow if you enjoyed it you might enjoy becoming a member of our channel channel members can submit questions to our qq inbox or see exclusive behind the scenes photos if you're interested you can get started by clicking the join button below this video END_SELFPROMO_TOKEN