Tack rags are commonly used just before painting. They will remove the light dust and dirt from what looks like a clean, ready to paint or varnish surface. Awlgrip's Deluxe Tack Rags are some of the best on the market.
WARNING: This product MAY expose you to chemicals, which are known to the State of California to cause cancer, birth defects and/or other reproductive harm. For more information go to www.p65warnings.ca.gov