All materials
Material
Foam
Cushions, insulation, craft foam
Default glue
Foam-safe spray adhesive
No solvents, so it can't melt the foam.
Identify
How to tell it’s foam
Squeezes flat and springs back. A cut edge shows a sponge of tiny bubbles.
Character
What it’s like to glue
Mostly air — the solvents in many adhesives literally melt it, polystyrene foam worst of all. Water-based and foam-safe formulas only.
Alternatives
Other glues that work on foam
AvoidAnything with strong solvents — it dissolves polystyrene foam on contact.