Pliofilm was a clear plastic (rubber hydrochloride) developed by Goodyear, used for wrapping and storage (and clothing!). They made a great series of ads, of which I've found barely half. If you discover more (there's another similar series of which I have only 2, as well), please let us know.
Herewith, their A-Z series from the mid-1940s (1946-48). Or rather, B, C, D, F, G, J, L, M, O, P1, P2, R, S1, S2, W, & X. Not surprisingly, they were straining with "X". ;D
ETA: Thanks to
noluck_boston for tracking down A, C2, and M2! :)
A preview: