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What to Know About Varnishing in Winter

As a Christmas gift to myself, I asked Hans, my Norwegian cabinet-maker friend, to build some new upgrades for my old and beloved 1968 Venture 21. These included drop boards for the companionway, a bulkhead liner for the V-berth and a mounting board for a bilge pump, all of which he delivered on time to my dock in Olympia, Washington, rough-sanded and ready.

As a Christmas gift to myself, I asked Hans, my Norwegian cabinet-maker friend, to build some new upgrades for my old and beloved 1968 Venture 21. These included drop boards for the companionway, a bulkhead liner for the V-berth and a mounting board for a bilge pump, all of which he delivered on time to my dock in Olympia, Washington, rough-sanded and ready.

The only problem? It was the dead of winter, and I didn’t want to wait for spring to do all the varnishing. Nonetheless, betting on what I already knew about varnish, I took up the challenge. I brought the pieces home and set up a work space in my garage.

Careful preparation

Here in the Pacific Northwest, the winter temperatures in my garage can drop to 40F and humidity can climb as high as 70 percent. Therefore, keeping the work surface temperature up at the required 50F meant running heat lamps continually.

I could roll up the garage door only so much and so often as “sun breaks” permitted. In no case did I move the work in and out of the garage; the abrupt change in the temperature and humidity would be ruinous.

I already had two small construction site work lights on hand that would work well as heat lamps, as well as a pedestal-mounted household room fan and a three-gallon compressor. My weapon of choice when varnishing is the natural bristle brush, but because I’d used foam brushes and sponges on some earlier projects, I had a few of those as well.

As a first step I gave the garage a thorough cleaning. I also resolved that everything would be hand-sanded, since machine sanding puts too much sawdust in the air. I then filled the joints and the tears in the grain, worked everything with 150 grit paper wrapped around a block, and took each piece outside and blasted the grain with my compressor. I never sanded and varnished on the same day.

As a next step, I brushed on the filler/stain, rubbed it out well and let it dry for 24 hours. Without this last step, the stain can re-liquefy and dull the varnish. The varnish itself was not thinned, and between each coat I sanded the surface first with 320 grit paper and then later with 400. After that I scrubbed the work with a stiff nylon brush, hit it with the air compressor, rubbed it vigorously with a towel dampened with Pure Gum Spirits of Turpentine to remove the “chalk,” and then again blew off any lint left by the towel.

No amount of scrutiny is wasted here. Between each coat, the surface must be cleaned. Otherwise, minute debris lodged in the terrain will wash out and become entombed in the layering, always in a conspicuous place. Likewise, your favorite brush can never be too clean (again the compressor plays a role here), while a brand-new brush is not clean at all.

Before layering down each coat, I removed the heat lamps and fan so the surface wouldn’t be overly warm. Cold temperatures can affect varnish performance, but cool varnish gives a longer brushing window.

To clean up the brushes between sessions, I would rinse them several times in diesel, blow them dry with the compressor and saturate them with WD-40.

Don’t brush what you can’t see

Varnish does not flow from a brush evenly. Brush marks and weird effects that would ordinarily show themselves easily in sunlight will thumb their noses at you in artificial light. I prefer bristle brushes because the filaments conform to the terrain, or “hit the ditches.”

When varnishing I would hold the brush in one hand and wave a 609-watt bulb back and forth with the other. It’s amazing how the coverage and surface tension will vary from place to place, and the light will tell you where more work is needed. Don’t let the lightbulb get too close. If the varnish sets on a dropped brush hair or a kamikaze insect, trying to repair the damage may ignite latent hostilities in your personality.

My objective whenever laying on a fresh coat is to use as large a brush as possible, make as few brush strokes in as little time as possible and end with nothing in the cup. Never return the left-over varnish in your cup into a can.

For each session, I would spray the room with insect repellent and make sure the clothing I was wearing would not shed any lint. I also made a point of never reaching my arm across the work and never using varnish straight from the can. With a formidable build-up of varnish established, I could switch among my tools: one layer could go down with the bristle brush, the next with the sponge or the foam brush, after which it was back to the bristle brush. Be aware that if a foam brush is worked dry, it will take varnish back from the surface. Do not mop with sponges, and toss them when they get soggy.

When is it dry?

Once a fresh coat was down, I would move in the heat lamps, but no closer than two feet. I would then set the pedestal fan on low to move air but not raise dust—hence the need for a clean work area. I would also re-position the lamps periodically.

“Dry to the touch,” does not mean the work is ready to handle. Hardening came only after two days under the lamps. When the surface is hard, the sanding residue will be powdery, if not it will roll off like little hotdogs.

After each build-up coat, I took a single edge razor blade and cleaned out the corners and then gently drew it across the open areas. You’ll hear a crackling sound if the blade strikes a flaw, like an air bubble that dries and breaks. I followed with 400 paper. To get sandpaper into corners, fold a small piece around the tip of a sharp spatula. Don’t run the razor on the final coat.

Varnish is beautiful only when the terrain is full and level and devoid of any light catching “anomalies.” How many coats?

How easily are you satisfied?

Yes, of course use only varnish with ultra-violet protection ingredients, but to go one step further I poured on auto wax, which I worked in with cheesecloth. Polish won’t improve the varnishing per se, but tremendously in fending off Pacific Northwest weather. This step also helped me to clear off any “ticks” that remained by taking up my razor blade again and then drawing it through the wax. With plenty of wax on the surface, this final razoring is less likely to mar the finish.
Although, owning an expensive boat helps, don’t hope for any compliments from friends until you’ve applied at least 10 coats. Breaking the stride of a stranger walking along the dock is unlikely to occur before 20.

Eventually spring came. I was at my boat on a sunny day and carefully slid the drop boards down into place. The reflection of my wristwatch flashed across the varnish like a strobe light. I could almost read the time. It was about noon. My dock neighbor came up and said, “Hey, let’s go to lunch.”

Technical writer John Arrufat sails his
Mariner 31 in Portland, Oregon and is half way through
writing a high seas adventure novel.

Materials Used

The drop boards are Luan, framed with Apitong. The mounting board for the bilge pump is mahogany veneer on marine ply. The front panel to my V-berth is clear Cedar.
Varnish: West Marine’s Captain’s Varnish. Miller Clear Gloss is a great build up.
Wood filler: I used PL filler. Whichever brand you prefer, get the appropriate solvent so that you can thin the filler and run it into the smallest crevices.
Filler/Stain: Miller clear Preserva. The chemistry should be compatible with the varnish.
Wax: Turtle Wax and Howard’s furniture wax.
Sponges: Drug store cosmetic sponges were used for the long wide featureless bulkhead liner.
Filters: Fine mesh paper cones doubled up and blown clean, about fifty for the project.


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