Sealing coat? No - according to the latest Newsletter by Nowfound boatworks. No-according to the article on glassing in the last issue of Wooden Boat Magazine.

I have built four - 3 without and one with a sealing coat. I'll never seal again.

Nothing is going to beat the bond of epoxy soaked into bare wood espeically when it's sanded with 100 grit or less. Newfound newsletter is suggesting 80 grit with the grain. Warm your room several hours before glassing to release any air entraped in the fibers. good luck.