Carl wrote:

Lew might have been more helpful in his answer.

You need to apply epoxy "tank resin" as the final interior coating for a
fuel tank if you expect it to survive as defined by federal CFR spec.

Laminating epoxy and knitted glass provide the strength and protection
of the plywood core.

Epoxy tank resin, a totally different epoxy product, provides not only
protection for the laminating resin, but also a non porous interior tank
surface.

Lew