a good jaw workout

July 30, 2007 12:42 PM

Why does chewing gum go all stiff and inelastic when you drink cold water?
posted by irregardless to Food & Drink (4 answers total)

In metals, plastics, and organic materials, heat contributes to how malleable an object is. Gum is made to be soft and pliable at mouth-temperature (98.6).
posted by hermitosis at 12:59 PM on July 30, 2007

Exactly - heat makes things softer (generally) and cold makes things harder, less elastic and more brittle (generally.)
posted by Dee Xtrovert at 1:05 PM on July 30, 2007

Response by poster: I guess I should have asked -- why does it stay stiff and inelastic? I would have thought that once the gum returned to mouth temp, it would go back to being, well, gumlike. Not so (for me, anyway). Why?
posted by irregardless at 1:21 PM on July 30, 2007

Well, from poking around on the web, there are probably a couple of reasons. First, gum is usually made of an artificial polymer that will "set," much like other polymers. But added to it are a bevy of chemicals to improve its flexibility, usually glycerin, gelatin or vegetable oils, which are all blended in to remain in solution in the gum. In more recent years, hydrophilic (water-soluble) additives have been patented and used, which likely exacerbates the problem, in that in addition to rapidly cooling the gum, you're also washing away all the additives that you've worked back to the surface of the gum by chewing. (The hydrophilic additives have become more popular because it keeps gum moist longer prior to chewing, but they're removed more easily by saliva).

Now, granted, this is mostly supposition based on a quick read of some patent literature and a few "making of" sites, but I think it's more complete than the above answers.
posted by klangklangston at 2:33 PM on July 30, 2007