Roy's right on the money, if it sticks and forms a skin it will work. Shellac, poly, wood glue, wax, some paints.
I've got a gallon of anchorseal 2 that I use for sealing logs for the mill. Works really well if you use it quickly after cutting. It's a very waxy coating that makes a very good seal, and gap fills o some extent if some minor checking is already present.
Shellac and wood glue are much easier to remove later on when working on your bow.