In The East: How to Finish Your Kayak

December 05-January 2006

This is an article from WaveLength Magazine, available in print in North America and globally on the web.
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by Adam Bolonsky

So you’ve decided to take the plunge and build a wooden kayak. Congratulations! It’s an excellent choice. With just a little care and effort, you should end up with a boat that’s lightweight and beautiful. Here’s how to ensure your success.

EPOXY—DON’T OVERDO IT

Epoxy is the key ingredient in building a lightweight, good-looking boat. It’s also easy to overuse. Be sure you use only enough to (a) seal and waterproof the wood and (b) bind the fiberglass to the wood.

If you use too much epoxy—a common error among first-timers—your hull’s fiberglass sheathing will end up floating over the wood instead of tightly glued to it. Not only will a too-thick layer of epoxy and add unnecessary weight, it will compromise the strength and durability of your kayak by holding the fiberglass away from the wood. You want the wooden hull to do its work of providing beauty and low weight, so let the epoxy and fiberglass to do their work of providing strength and durability by being sure the fiberglass is in as close contact as possible with the wood. To do so, ‘dress’ the epoxy when you apply it.

To dress epoxy, gently spread it over the fiberglass with an auto body applicator so that any pools of epoxy which form in the fiberglass when you first wet-out the glass don’t end up pooling in too-thick layers between the glass and wood. Dressing saves weight too, especially if you dress the epoxy when you apply the subsequent coats to fill the fiberglass’s weave and to smooth it over. If you take care to thin and smooth those second and third fill coats, you’ll ultimately create a more easily sanded surface come time to paint or varnish the hull. Any areas you can’t dress with the auto body applicator, dress by a jabbing motion with the tip of a cheap brush.

If you take care to dress your epoxy, being sure to smooth it down and to flatten out any sags, drips, gobs and ripples, you’ll remove much of the excess epoxy—and the unnecessary and expensive weight that characterize most first timers’ hulls.

THE FINISH—BRIGHT IS NICE, BUT CHOOSE WORKBOAT

The essentials for a durable and smooth clearcoat application.

When it comes time to transform your hull into a showpiece by way of finish, you have two choices: bright and workboat.

Of the two, bright is probably the most popular, at least among first-timers, because a bright finish strikes the untrained eye as the most beautiful. Bright means you apply to every square inch of your heavily sanded hull either six coats of varnish, three coats of two-part clearcoat, or both. It’s a nice finish that lends to a wooden kayak a classy if somewhat over-obvious look.

Fiberglass cloth turns transparent when it’s saturated with epoxy, so after you apply varnish or clearcoat, the grains and figures of the wood below are emphasized by the varnish’s deep amber glow or the clearcoat’s transparent window. Deck, gunwales, hatches, coaming, hull, keel—all combine to form a mesmerizing pattern of swirls, whorls, waves and ripples which the varnish or clearcoat emphasizes brilliantly. Bright is an eye-catching look and on strip-built kayaks it adds a dazzling flourish, which is why most first-timers choose it.

There are drawbacks however. While a bright finish can be stunning, especially on first look, every mistake you make in your application of epoxy, filler or bonding agents will stand out, and ditto for any discolorations or scratches or gouges you inflict on the wood while building. These can detract from the final look. Also, you cannot fair, or fill the dips and hollows, in a bright hull. Fairing compound stands out as garishly as bandages on a wound.

Plastic spreaders for applying epoxy and dressing the epoxy out. Epoxy won’t adhere to them and simply flakes off like dried scabs.

Moreover, to create a bright boat, you need to apply at least six coats of varnish, or three of clearcoat, to achieve a deep, clean look. Also, varnish is soft, so if the hull is dragged over beach, rocks, or berm (even slid from a car roof), it scratches and gouges easily. Any number of milky-looking scars will result, leaving even the best-built hull looking shabby, worn out and uncared-for. Varnish is a pain in the butt to apply as well: a good-looking job takes timing, luck and skill. Temperature and humidity have to be just right. Varnish is prone to dust dimples, sags and lace curtains as it dries. In essence, the more bright you create, the more landscape you have on which to make mistakes.

The workboat alternative uses a combination of varnish (or two-part clearcoat) on the deck, and paint or stain on the hull. To my eye, the workboat look is far more pleasing because the visual interest of the bright deck is set off by the hull’s contrasting or complementary paint or stain. Workboat brings out the beauty of a wood hull without overdoing it.

Six successful coats of varnish (or three of clearcoat) applied to deck alone are quite an achievement, and plenty beautiful, if not more so, than a totally bright boat.

Typically, the workboat look requires varnish or clearcoat on the deck, hatches and coaming, and paint or stain on the gunwales, sheerline and hull. Not only is there less varnish (and fewer scratches to fret over), but the workboat look lets you customize your kayak so that it becomes unique among all the hundreds of all- bright kayaks on the water. You varnish (or clearcoat) only some wood. Then you tape off a border and cut in (or stain, before glassing) a contrasting or complementary paint.

KEYS TO QUALITY

Charcoal-activated respirator (crucial for protection from clearcoat’s volatile organic compounds) and sanding disks.

Regardless of which finish style you choose, here are some keys to high quality work.

After your final epoxy coat has cured, sand the entire hull. Use four grits: 80, 120, 180, 220. Also known as ‘living in the House of Pain’, sanding a glassed wooden hull is tedious, noisy work akin to, oh, I don’t know, leaf-blowing a golf course using a hair dryer attached to your forehead. Wear earplugs and a respirator (not a dust mask). And be sure you buy your sanding disks on mail order lest you spend as much on disks as on building materials and tools.

After you have sanded through the four grits, wet-sand the hull with 300 grit. Wet sandpaper is waterproof, so wet down the hull, dip your sanding block into bucket of water, sand like hell, and rinse the hull. You’re done when, once the hull dries, you see nothing but fiberglass that’s dull and foggy-looking. Shiny spots are areas you haven’t sanded well.

If you plan to paint, examine the hull from several angles. With a pencil, circle the shiny spots you failed to sand out. Fill them with fairing compound, such as West System’s 410 fairing compound (microballoons), then sand the fairing compound before priming.

When you’re ready to paint or varnish or clearcoat, rinse the hull once more to remove any sanding dust, then wipe the hull clean with a rag sprinkled with whichever solvent applies to the topcoat you chose: mineral spirits for varnish, or the proprietary solvent for your one- or two-part paint or clearcoat.

Be sure to check your epoxy supplier’s tech specs, however, before you do any of the above. Some epoxies form a ‘blush’ while curing that needs to be rinsed with solvent.

So now you’re ready. Using a technique known as roll-and-tip, with roller in one hand, brush in the other, apply the several brilliant coats of varnish, paint or clearcoat. Apply at least six coats of varnish, three or four of paint or clearcoat. Sand and wipe between coats, according to the manufacturer’s specs. Choose days when the humidity is low, and do not work in direct sunlight, as both conditions can fog and wrinkle the finish’s initial skim coat.

Once you’re done, hang your hull on the living room wall, then go right back out and build another boat you can beat on because chances are you’ve just finished a kayak that looks too pretty to paddle.

My advice: paddle it now. The first scratch is the worst. Then you get over it.

VARNISH WITH 2-PART CLEARCOAT

Varnish on the deck of a wooden kayak adds to lovely wood an amber tone with a glow that deepens with sunlight exposure.

The problem is, varnish scratches easily, forming unsightly mars.

Here’s one way to use varnish and protect it from everyday abuse: apply, over your six coats of varnish, two to four coats of two- part linear polyurethane clearcoat.

This beauty was finished in a spray room by a professional auto body shop at a cost of about $400. It has two coats of two-part linear polyurethane clearcoat. © Roger Turgeon photo

Two-part clearcoat is a tough, industrial- grade coating that will put a remarkably hard and durable finish coat over varnish. Adapted from the non-consumer two-part paints used by airplane manufacturers and custom yacht builders, two-part clearcoat’s hardness and durability rival that of gel- coat. Apply a few coats over six coats of varnish and you’ll get the best of two worlds: the beauty of varnish, the protection of a scratchproof, transparent topcoat.

Here’s how to do it.

Wait until paddling season is over or until your hull’s varnish has cured for 30 days or more. If you have paddled the kayak for the season, rinse it and lightly wet-sand with 220 grit or so. Take great pains to smooth out any scratches and gouges the varnish collected during the year, and try remove just enough of the gloss of the varnish to create the microscopic scratches a fresh coat of varnish will need in order to adhere.

Rinse the hull again and clean it with solvent. Using roll-and-tip, apply a fresh coat or two of varnish. A few feet above the fresh varnish, suspend a plastic tarp that will shield the varnish from dust that may be in the air in your workroom.

Give the fresh varnish thirty or more days to cure. (If you fail to wait long enough for the varnish’s solvents to evaporate, the next step, applying two-part clearcoat, will simply lift off the varnish.) After the 30 days, roll-and-tip two to four coats of two-part clearcoat over the new varnish. Be sure to follow, to the letter, the manufacturer’s specs for the ratio of catalyst to solids. As for thinning, to check the more flexible ratio of thinner to catalyst/solids, roll out a test strip of mixed clearcoat on a vertical pane of glass or plexiglas. If the mixture runs, you’ve added too much thinner. If too little, the two-part will sag in a wave pattern.

Apply the carefully thinned clearcoat with roll-and-tip and allow to cure. Be sure you use a phenolic roller (see West System), as only a phenolic roller can withstand the two-part’s solvents.

If applying multiple coats, lightly sand between coats according to the manufacturer’s specs.

Be prepared to pay a pretty penny for two-part clearcoat: about $70 (US) per quart.

Two-part linear polyurethane clearcoat manufacturers include Interlux, Sterling and Imron.

© Text and photos by Adam Bolonsky, a native New England sea kayaking instructor and sea kayak fishing guide based in Gloucester, Massachusetts.