Anyway, I would "seal" the ENTIRE drum shell with Polyurethane (Min-Wax brand..... Clear, Satan finish). You can apply it with a rag, but, I prefer paper towels, BUT, be careful, You may get fibers from the paper towel (or rag) into the polyurethane. If you do, you can re-sand with 220 in those spots and try again. It takes a lot of patience, but, I nevermind the little fibers, it's hard to tell they are there.
Thanks, Ludwigdrummer. I was planning on sealing the inside of the shells. I'm gonna use the Min-Wax poly clear satin in a spray can. I used this on a '70s 3 ply 20" maple Luddy tom shell refurb that I added to my outfit. Looks just like it came from Ludwig! I know the mahogany will probably "soak" it up more than the maple. May take a couple of spray-on coats. But like you said, just wanna get nice coat to protect it. Lord knows, there's no tell'n where Dad may end up on some gigs. They sometimes perform out-doors at church picnics & festivals.
I also remember reading a thread on this board somewhere by "fungus-amungus" the he too, likes to seal the inside of his drum shells to enhance the tone.