Wipe-on Finishes and More
(Which Applicator and When)

by Michael Dresdner

Most coatings are formulated to work best with a particular type of applicator, but some work nicely with more than one. Knowing which coatings favor which application techniques can help you get better results. To that end, here’s a rundown of the various common finishes and some of the best application strategies for each.

Oil based varnish or polyurethane:

• Scrub on unreduced finish direct from the can using a nylon abrasive pad; wipe off completely to leave a thin, even coat.
• Brush with a soft bristle varnish brush of ox hair, badger, fitch, or a blend. Thin 10% to 20% with mineral spirits.
• Spray with a fine 1 mm (.040”) tip thinned up to 100% with mineral spirits, naphtha, or acetone.  
• Spray from aerosol can

Waterbased lacquer or polyurethane

• Paint pads are ideal for applying waterbased finishes on flat surfaces.

  On flat surfaces, use a paint pad to apply very sparse coats that make the wood just barely wet. Do not reduce.  
• On carved or fluted surfaces, use a soft bristle synthetic brush, such as nylon, Taklon or Syntox to apply very thin coats. Do not tip off. If you must reduce, use small amounts of Floetrol.
• Spray without reducing, using a fine 1 mm (.040”) fluid tip. If you must reduce, use small amounts of Floetrol.
• Spray from aerosol can

Shellac

• Flood on and wipe off immediately for the first coat only.
• Brush with soft bristle brush reduced to 25% solids with Bekhol solvent or butyl alcohol. Do not tip off.
• Spray with standard lacquer tip reduced with denatured alcohol to 25% solids or thinner
• Shellac-Wet will help finish lay out better whether brushing or spraying.
• French polish using a soft pad of cotton or wool covered with linen
• Spray from aerosol can

Lacquer
There are two very different types of lacquer. Brushing lacquer is designed for brushing with a soft bristle brush. Spraying lacquer is designed to be sprayed. Both can be used as is from the can, or can be reduced to any degree with lacquer thinner.

• Apply brushing lacquer with a very soft bristle brush. Do not tip off.
• Apply spray lacquer with a standard 1.75 mm (.070”) lacquer tip
• Reduce as much as needed for smooth spray or easy brushing
• Spray from aerosol can

Application tips

Below are some guidelines on getting the most from your application tools, such as spray guns, pads and brushes, as well as specific techniques that apply to particular finishes. But before we get into specific applicators, it’s worthwhile to say a word about sanding between coats. You always want to apply finish to the smoothest possible surface. Therefore, if you have any dust nibs, raised grain or applicator marks in the previous coat, it is wise to sand just enough to smooth them. That usually means 400 grit paper and not very aggressive sanding. After all, you don’t want to cut through. If your last coat was perfectly smooth, there is really no need to sand between coats for the sake of adhesion unless you wait more than two or three days between coats. In that case, you will need to sand for adhesion, but as long as you apply a coat each day, sand only when needed for smoothness.

Rockler’s Wundercote is a handy waterbased alternative to wipe on Danish oil finish.

Wiping

You can apply the first coat of shellac or any oil based varnish or polyurethane by wiping it on and off. I prefer to scrub the finish on with a nylon abrasive pad without thinning or adding anything to it. Wipe it off immediately, working in small areas for a fast drying finish like shellac, or in larger areas for slower drying oil based finish. When using shellac, you’ll have to switch to a different application method after the first coat since each coat dissolves the last. However, with oil based coatings, all subsequent coats may be applied by wiping on and off the same way, at the rate of one coat per day.

Wiping leaves no brush marks, creates little waste, avoids air bubbles and dust nibs, and applies thin, quick-to-dry coats. It’s long been a favored method for applying oil based finishes, and now there is even a waterbased wipe on finish. When you are done, spread the nylon pad and the wipe cloths out one layer thick and let them dry, which usually takes about a day. Once they are dry and crusty, they are safe to throw away with the household trash.

Lay out any oily rags or pads one layer thick to dry.

©2008 Woodworker's Journal

Next Page: Brushing >>