I do not believe that @Beekissed meant the entire thing, frame and pad, are wrapped in the trash bag but that trash bag is on top of the frame, same as using Press and Seal on top. I didn't bother with the "impervious" layer, just wrapped the whole thing in an old flannel pillowcase and put an old towel on top. The pad was plenty clean when they were done with it in 3 weeks when Zorra decided she wanted to "Mother" them after all.