i was reading about different foams and i was wondering is XPS the foam that Clark used to use and what does EPS look like? how can i tell the two apart? for making and epoxy board i hear that i should use EPS is that true?

First thing you need to get before buying foam is my profile table that I am selling for 4K. A must have!

P.U. is what Clark used/uses. P.U. for polyurethane

XPS is extruded polystyrene and its blue in color.

EPS is expanded polystyrene and its white in color, looks like your packing beaded foam.

You can glass all the above with epoxy.

But the machine its a must have. My loss your gain.

EPS is styrofoam. actually, styrofoam is a brand name of EPS. it looks like your disposable beer cooler.

Clark (and Walker, and many other companies) use(d) polyurethane foam.

XPS is something else entirely.

This is traditional PU (poliuretane) foam, only available in surfboard foam blanks:

And this is XPS (eXtruded PoliStyrene) which is only available in 2cm to 10cm thick sheets. It comes in different colours (blue, grey, pink, orange,…) depending on the brand.