Wet sanding

When you paint with oils, the sur­face doesn’t nat­u­rally come out flat. There are nor­mally lit­tle bumps and streaks formed by appli­ca­tion and manip­u­la­tion of the paint. Some artists delib­er­ately use this ten­dency to cre­ate a tex­tural or sculp­tural effect; this is called impasto. How­ever, in mul­ti­lay­ered paint­ing, sur­face tex­ture is often not desired. If you are going to add fur­ther lay­ers, you often want to add them to a flat sur­face. This is espe­cially true with glaz­ing, since tex­ture will cre­ate places where extra paint pools, cre­at­ing a mot­tled effect. You can reduce sur­face tex­ture in wet paint by gen­tly feath­er­ing with a clean dry brush after you’re done paint­ing. That tends to blur edges slightly, how­ever, which may not be desired. And some­times you miss a spot.

Once the paint has dried thor­oughly, it is some­times advan­ta­geous to sand the sur­face down slightly. In order sand very smoothly, and in order to avoid breath­ing pig­ment dust, it is best to use a wet sand­ing tech­nique. Lay the paint­ing down on a flat sur­face. Spray some water on the sur­face, or wipe it down with a wet cloth (adding a few drops of dish deter­gent is help­ful for lubri­ca­tion). Now use a wet green kitchen scrubee pad to gen­tly sand the sur­face. Unless you want to remove some mis­take, the idea is to lightly rub the pad around, with­out apply­ing sig­nif­i­cant down­ward pres­sure. Some paint will come up and the water will change color; that’s OK. Do this over the whole sur­face until it feels smooth. Now, before any evap­o­ra­tion occurs, wipe all of the dirty water off of the sur­face with a paper towel. That way, you don’t have to worry about breath­ing pig­ment dust. Let the paint­ing dry before paint­ing on it again; often an addi­tional day is a good idea to allow any tacky paint revealed by sand­ing to dry out.

Wet sand­ing removes unwanted impasto, removes sur­face gloss and cre­ates a uni­form satin tex­ture, and pro­duces a sur­face that is easy for the next layer of paint to adhere to. It’s often a good idea for indi­rect paint­ing. Wet sand­ing cre­ates an invit­ing sur­face that really feels good to paint on.