If you play with it too much, it stays soft? (Silly Putty)

I have a large blob of generic “Silly Putty” on my desk, made from several eggs worth of generic-brand putty. A coworker of mine has the same amount, from exactly the same sources. After several months, mine is much softer and stickier, where her’s is the same consistancy as day one. This is no doubt because I play with my putty more.

What I’m wondering is, is this simply from the putty absorbing hand oils and sweat and such, or is it actually breaking down? Or a combination of both?

It’s probably a combination of grease and dirt getting into the putty from your hands and the increased exposure to the humidity in the air that happens when you “work” the putty. Is it possible that your office is significantly more humid than your coworker’s? That would also make a difference.

It’s almost a lock that any chemical changes or breakdown due to age would be the same for both samples of putty (and therefore not a factor in the different consistency), provided they were close to the same age when you bought them. Unless there is some kind of hydrolytic aging reaction going on, in which case the fact that your putty has presumably been exposed to more moisture would make a difference.

Look, I can be only marginally on-topic and also answer why Hasbro is stupid!

The Curse of Flubber!

The point is Flubber, at least, has no trouble with breaking down chemically, much to the chagrin of Hasbro. Silly Putty has very similar properties. Let’s hope it’s more biodegradeable.

Aha! An area of expertise I seldom get to use… I work at a strange office with hundreds of people, most of whom have at least one good-sized blob of silly putty. We order it in bulk. I could tell you why, but then I’d have to kill you.

Anyway, some observations I and my coworkers have had about silly putty are 1) putty that doesn’t get played with much stays firmer, and sometimes even dries out to some degree, and 2) putty that does get played with changes to a slightly darker color. I believe point 2 is caused by oils and dirt from our hands getting into the putty. Point 1 seems to be due to the fact that a blob of putty “sweats” over time. A lab I worked in had a nice basketball-sized blob that mostly sat on a shelf for people to rip chunks off of when they needed some. The blob usually sat there, slowly flattening and sweating, and every once in a while someone would pick it up and make it nice and round again and bounce it on the floor for a while. This rubbed off the oil that had come to the surface, and eventually the blob ended up much drier than the oft-played-with blobs most people had. So now when you go to rip a piece off, it breaks more easily, since it’s stretchability is diminished.

Hope that helps.