State Historic Site
By Cynde Georgen; for The Western Alliance of Historic Structures & Properties, 1997
SOMETIMES THE ONE thing we need to do most is the one thing we least want to do. This is true of varnishing exterior doors. if your exterior doors are natural wood or gained, however, y ou need to have a good coat of varnish on them at all times. This protects the wood from the elements.
The problem is that the sun and rain also attack the varnish, reducing its ability to protect the wood. The solution is to revarnish at least once a year. As daunting as it may sound, varnishing a door in good condition is a simple procedure - much easier than varnishing a door that has been allowed to slip into disrepair.
Remove all hardware from the door before beginning any refinishing. It might be a pain, but it will make the rest of the job so much easier. If you can easily remove any screens or glass, so much the better. If you can't, tape off the edges so your varnish won't stick to it (varnish is easy to apply but not so easy to remove). Take advantage of this time to remove any debris (bug parts) from the hardware.
Before applying a fresh coat of varnish, the old finish must be sanded. Even if the previous finish is still in good condition, you must sand in order to take the slick finish down to a rough condition. This promotes good adhesion of the new coat of varnish.
If your old finish is in poor condition, you will have a much harder job ahead of you. Sand until the finish is even, leaving no peeling patches or discolorations. You may have to sand down to the bare wood in some places. As with all sanding projects, remember to sand gently along the grain of the wood; sanding across the grain will cause unsightly scratches that will be clearly visible through the finish.
DUST, DEBRIS & WEATHER
After the sanding is finished, all surface dust must be removed by wiping with a tack rag. You can buy one at any paint store or you can make your own. On a piece of dry, lint-free cotton cloth, sprinkle varnish that has been diluted with 25" turpentine. Fold tightly, then wring the cloth out until almost dry.
For a good varnish job worthy of the door to which it is being applied, it is absolutely essential that everything be clean: brushes, materials and surfaces as well as the surrounding area. Don't varnish outside on a windy day when dust and leaves could land on your project! Aside frm wind, there are other weather conditions to keep in mind. Teamperatures below seventy degrees are likely to cause trouble. Humidity is also a problem; it can cause "bloom" - a thin white film caused by moisture in or on the varnish while druying.
As for the varnish itself, use one that is clearly labeled for exterior use. One of the best is "spar" varnish. This is a very durable product designed for severe weather conditions. It gets its name from its original use on the spars of ships. There are other varnishes not as heavy as spar, most of which come in a variety of finishes (gloss, satin, etc.) Try to avoid polyurethane finishes as they do not stand up well under the intense UV rays of our western sun.
Brush the varnish on in a thin, even coat and let it dry thoroughly before touching. Depending on the door, its level of exposure, type of varnish used, etc., you may have to add two coats. If so, you'll need to lightly sand the finish between coats. This can be done with very fine steel wool. Once again, be sure you sand in the direction of the grain.
Carrying Varnish Don't use a full can. There will be less chance of spillage, the can will be easier to carry, and it will allow you to control the amount of varnish you get in the brush.
Loading the Brush Dip the first third of the bristles into the varnish; slap it smartly but lightly against the inside of the can, once on each side of the brush.
Removing Bristles from Wet Varnish Stab the bristle (or other foreign object) with the tips of the bristles and carry it off the west surface in a scooping motion. Pick it out of the brush and immediately straighten out the messy area.
Straightening Strokes To avoid lap marks, always draw your brush lightly over the wet varnish in long, continuous strokes. Straighten out your brush marks from end to end.
Panel Doors Paint the mouldings first, then the recessed panels, then the outer pieces. Always paint with the grain of the wood. When you come to a "T," paint the leg first, then the crosspiece.