So looking at the back of my otherwise very clean vapor canister it has some "stuff" on it that looks like contact cement. Seems to have brush strokes. But nothing was adhered to it. The front side (facing inboard) is free of this stuff.

Anyone know what this is from?

Edited March 31Mar 31 by Broman

It use to have a piece of fiberglass batt insulation glued to it to prevent heat gain from the car body

Interesting. Does anyone have a pic and/or any dimensions of this insulation?

I tried to find one on Google images but couldn't.

The insulation is yellow fiberglass batt.

Maybe ¾" thick, roughly the shape of the tank