Sandpaper is a rough material that is used for smoothing or cleaning surfaces such as wood, metal, or walls. It has a gritty texture that helps remove imperfections and make things smoother. Full definition
Once you get the boards home, you'll want to sand all sides of the board with a fine grit sand paper. (dahliasanddimes.com)
I did distress with fine sand paper after I painted to have some of the wood show through. (athomewiththebarkers.com)
Before applying the chalk paint use sand paper, soap, dry / wet cloth, or anything useful to make sure the surface is cleaned properly. (mommyiscoocoo.com)