Before & in between priming I use an older but not ratty pillow case. The material is less likely to leave behind unwanted fibers. This is a light way of removing any remaining sanding particles or rough spots from primer by gently rubbing. Some Artsy folks use socks or dish linen.
Recommend using gloves so you do not leave oil residue left by your fingers, it will effect the paint work.
Resin cast is by Debbi Lermond sold out edition Working For Chex.