What if need this exact thing? Where would I find it again if I carelessly threw it out now?

This Black Foam is what foam?

You’re looking at something that’s dense, a bit squishy, but takes effort to compress. That puts it ptobably in the category of either XLPE or EVA foam.

Cross-Linked Polyethylene (XLPE)

• Smooth outside, super fine closed-cell texture
• Somewhat difficult to compress, bounces back fast
• Used in stuff like Pelican case inserts, insulation, flotation pads
• Basically waterproof, holds up well to abuse

EVA Foam

• Slightly softer and more flexible than XLPE
• Still dense, but easier to push in
• Shows up in gym mats, cosplay armor, cheap padding, shoe soles
• More likely to soak up a little moisture if submerged

How to Tell Them Apart

Thing to Check	XLPE	EVA
Texture	Finer, more uniform	A bit more irregular
Surface Feel	Smooth, maybe a little glossy	Matte, slight texture
Water Resistance	Almost totally waterproof	Mostly, but not quite as good
Squish Factor	Firm, takes effort	Softer, more give
Nail Press Test	Barely leaves a mark	Leaves a temporary dent

Quick DIY Tests

• Water dunk: If it stays dry, probably XLPE. If it soaks even a little, probably EVA.
• Fingernail press: XLPE resists. EVA gives in for a second.

If you know what this piece came from (like a shipping insert, exercise mat, insulation panel) that can help narrow it down even more. Let me know and I will give it a shot.