I was thinking of this product, yes.
Yes this is the kind of spackle use to seal surfboard eps blank. Just look at color often when they are white it's write. Some are greyish or tan. Need to be cut with distilled water to whipped cream texture then it's easy to spread right.
Liteweight (which is why the call it "Liteweight" Spackle) and white in color. That would be the stuff. Thin it like lemat said and spread with a plastic squeege. Thin with distilled water. Fill the voids don't coat the blank like you were painting it. Let it dry throughly and screen with a dedicated worn out piece of 220 screen or as some say "gauze". Sometimes if you have larger holes it is necessary to dab unthinned Spackle into those holes with a finger. Then squeege flat.
That which can be assorted without evidence was read in an illegal magazine.