Choose the right weather: Varnish indoors if possible. If not, avoid morning or evening damp, rain, bright sun or wind. Temps between 50°-80°F are the entire range where you can expect good results (ideal: 55°-65°F, with 45-55% relative humidity).

Avoid the “I have to do it today” syndrome: Be patient. Wait for the weather to be right. Sand thoroughly. Do all the prep work. This dreaded syndrome is the single factor responsible for more fouled up varnish jobs than anything else.

Use the right brush: Most pros use badger hair brushes; they must be carefully cleaned after each use. If you can’t properly clean them, your expensive brush will be wasted. If you don’t want to deal with linseed oil or kerosene solvents, you can get decent results with foam brushes. Badger brushes really matter only on the final two coats.

Use lots of coats: Generally, exterior wood will need at least 4-6 coats. Some varnishers apply as many as ten coats.

Application tips: Clean prepared surface using a shop vac with brush attachment, then wipe down with a soft rag lightly wetted with the solvent recommended on varnish can. Lightly wipe with a tack rag right before application. Strain varnish through a cone-shaped paper strainer into a small, clean can or jar. Don’t apply directly from can.

Be vigilant: fix those little nicks and dings before they get down to bare wood.