In response to yesterdays post about the 8×16 LED matrix which used ping-pong balls as diffusers, Josh send this video and warns that the Ping-Pong balls are made of a very flammable material (nitro-cellulose). So If you are making a project using them as diffusers, keep in mind they catch fire very easily.
I had designed a kit that used ping-pong balls as LED diffusers for a nightlight, then I saw a demo of a flaming ping-pong ball at dorkbot. They’re sort of hard to light when intact, but as soon as you make a sharp corner by cutting them, an open flame catches really quickly.
Just something to keep in mind when installing an otherwise-awesome piece like this one. Don’t put it along critical fire-exit paths, because it will be its own little inferno in case of a fire.
Via the comments.
Here’s one that someone posted on Hackaday a year or two ago when the flammability issue arose in the comments for another ping pong ball matrix: https://dl.dropbox.com/u/610802/fireshort.wmv
It’s so well known that ping pong balls are flammable yet people still keep using them :<
nice clean burn, can I use for rocket fuel?
I dissolve ping-pong balls in acetone to make nitrocellulose lacquer which I then mix with finely-ground black powder to make the igniters I use to launch my rockets…
@r4k
“finely-ground black powder”
You grind it yourself? If-so, gooood luck!
I grind it in a ball mill (rubber mill, lead shot) at the end of a *long* extension cord.
Grinding black powder is often done using a ball mill, much safer than alternative methods, like a mortar and mortar and pestle.
Though, if you smush ping pong balls, or grind them, wrap them in aluminum foil like a ball, and leave a small opening, they can be used as a very effective, cheap, and highly toxic smoke “generator.
Be sure to try it outside far away from people!
Nitrocellulose (‘”gun-cotton”) is both flammable and explosive, and weirdly enough was also used as one of the first substrates for photographic roll-film. It’s flammable nature had led to both the loss of life in theater fires as well as irreplaceable negatives and movies due to both fires and decomposition. Before the advent of acetate (“safety film”) and later polyester film stock, the projection room of theaters was like an armored, fireproof asbestos-lined room. The original nitrocellulose (celluloid) billiard balls were a bit… unstable and would often detonate upon hitting the floor after a flubbed shot, which could lead to tense situations in Old West saloons, where the explosions could cause every man-jack in the place to leap up, guns drawn. I remember that I researched this back in the early 70s when, as an avid teen-age photographer, I wondered why my Kodak b/w film was labelled “Safety Film”. Ahh…. the 1972 edition of the “Chemical Encyclopedia” – a fascinating source of pyrotechnical fun for me and my explosion-happy friends. We preserved life, limbs, digits and eyes by always using remote electrical ignition and a designated RSO – range safety officer.
I cut 32 balls with a hotwire-setup last year. Only one ball caught fire, but it was easily extinguished by just blowing on it. With my setup in the video it was easy to get clean and straight cuts.
Cutting table tennis balls with a nichrome hot wire
you probably cut one of the new poly plastic ones, if you had ignited a nitrocellulose ping pong ball,you would have to wait until it burns itself out, they will even burn under water, as they create their own oxygen as they burn. This means water won’t put it out, standard fire extinguishers won’t touch it, as they work by displacing oxygen or suffocating a fire with foam, they will just continue to burn, the older they get the more unstable they get, as they breakdown into nitro cellulose powder. The old tennis balls would sometimes ignite, just from the friction of hitting them. They are basically gun cotton in a round shape
So that was what blew up the theatre in Tarantino’s “Ingloriuous Basterds” :-)
Reentering the world of Celluloid collars and flaming billiard balls. There was a time when cheap nitrocellulose goods were a miracle, followed by the realization that, in a world of kerosene lamps, candles, white gas powered irons and open heating fires, they were an extreme liability.