I used to use balled-up cotton rags to apply wipe-on poly, but I’ve recently discovered a much better applicator. All you need are a bag of those inexpensive, circular make-up remover pads and some old knee-high pantyhose. I slip two or three of these cotton pads inside the stocking and wrap up the excess. The cotton accepts a good charge of poly that’s still easy to control, and the pantyhose keeps the cotton fibers out of the finish coat. It also lays down a nice, level coating without streaks.