I have a black leather cellphone case with a clear plastic “window” on it where my phone’s screen goes. Every few days, I take out the phone from the case and I find this clear, colourless, greasy substance that forms between the clear plastic window and the screen of my phone. I didn’t get that happening with my previous cellphone and I even used the same case. This also happens to my sister’s cellphone and case.
Anyone know where this greasy stuff comes from?
Probably plasticisers condensing on the case. Plasticisers are volatile compounds that are added to plastics to make them more flexible. They are typically oily compounds called phthalates. These can leach out of the plasticm especially in warm conditions. It’s the same phenomenon that’s responsible for the greasy layer on the inside of the windscreen of a car - the plasticisers come out of the plastic dashboard.
I almost forgot about this thread!
Thanks for the great explanation. 