We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
For finish coats on refinished or freshly done wood, Sippican recommends this stuff. It's what he used as a finish for his furniture: Deft clear finish.
I always listen to him. As an old-timey Yankee traditionalist, I figgered he'd go for for waxes or oils which I prefer on my gunstocks, but he likes a couple of coats of that Deft stuff, sprayed or brushed. I will not use polyurethane on furniture as my religion forbids it but that's not polyurethane. It's a lacquer.
I am still contemplating how to finish one of our old oak rustic, wide-board family dining tables which I sanded, steel-wooled, and stained. Why do that? Drink and other stains, and 90 years of grime, food, wax, dust, and dead mouse excretions. And rustic enough that I could not screw it up badly. Would never dare touch fine furniture. Maybe I'll use the Dreft Deft.
Regardless of which product you use, you are essentially using a "Clear Coat". While I prefer oil finishes over the others, there should be no doubt that a poly finish is tough and durable. Even in the 80's, there were (and still are) water based polys which are tougher than any other finish I am familiar with.
If you have a dark water/ink stain on an antique wood piece, you can generally remove it by mixing a paste out of Zud cleanser and leaving it on the stain overnight. Zud has an ingredient (Oxalic Acid) that does this. Other cleansers do not have this ingredient. I prefer Tung oil or Watco Oil finish on antiques as it is not overly glossy. I do take care to avoid doing things that might damage the finish on furniture.
Well, I am a traditionalist, too (and from New England). I work in a retail shop where we sell many tables. I prefer satin Varathane floor (yes, floor) varnish for it's durability and moisture resistance e.g. sweating glasses. I finish it with a coat of Oz cream polish - see Amazon; and Oz is great for antiques! Never had one complaint.