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Fiberglass finishes for woods

Radio Control Boat Modeler, Aug 2002 by Tritle, Pat

Secrets to a show-quality shine

When I started building strip-planked hardwood boats, I found that a high-quality finish was not difficult to achieve using Varathane or polycrylic varnish. The challenge was to keep the finish looking good over time without a lot of maintenance.

When I built the Dumas Continental, I finished the hull using 10 coats of polycrylic polyurethane varnish. It looked great until the boat went into the water; then it began to leak. After half a dozen runs, the hardwood planks had started to curl and separate to the point at which it became necessary to do major repair work.

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At the time, I was building the Dumas Cobra. To avoid the problems I had encountered with the Continental, I decided to fiberglass the Cobra hull. My dilemma was that I had little success using polyester resin, and the Cobra was already heavy. I decided to try sheathing the hull using Dan Parsons' 0.6-ounce fiberglass finishing cloth and West Systems epoxy resin. It worked perfectly. This finishing system is not difficult, and it produces an incredibly durable finish that requires absolutely no maintenance beyond being dried off after a day's running and an occasional coat of wax.

FIBERGLASS FINISH

Begin by cutting a piece of cloth to about 1 inch larger than the deck all around and draping it over the model. Mix your West Systems resin and thin it (70:30) with denatured alcohol. Brush a liberal coat of resin through the cloth, but don't use so much that it puddles; you just want a good, wet layup. Let it cure for 24 hours, then sand the excess cloth off the edges.

Next, turn the hull over and cut a piece of cloth to drape it entirely. Trim the cloth to overlap about an 16 inch on both sides, then trim the transom in the same way. Mix a batch of resin and wet the cloth from the keel outward. With a gentle coaxing, the cloth will conform to almost any curve. Continue until the entire hull is wet, and let the resin cure for 24 hours before you sand the edge.

Rub the boat well with a wet rag to remove the wax from the surface, and continue to clean the surface with water until the "medicinal" smell has disappeared. Brush on another coat of thinned resin, and allow it to cure for an additional 24 hours.

When the second coat of resin has cured, wet-sand the entire boat with 220-grit sandpaper until the surface takes on a "frosty" appearance. Wipe the water off frequently and pay careful attention to the shiny spots; they indicate that more sanding is needed. Also, be very careful not to sand through the cloth. Once the model has a smooth, uniform surface, remove all the residue and brush on another coat of resin.

Again, wet-sand the entire boat with 220-grit paper, and after an additional wet-sanding of the surface with 600-grit paper, the cloth weave should be invisible. If it isn't, recoat with resin and sand again.

The next step is to paint the hull bottom and add the water line. I used Floquil railroad paint for the hull and stripping tape for the water line.

The final coat of resin should be sprayed on. Thin the resin once again with denatured alcohol (50:50) and spray it onto the entire boat. I use a Paasche H-1 airbrush with a no. 3 tip. Tailor the resin mix to get a nice flow through the airbrush for a smooth wet spray. Build up the resin slowly until it's smooth and shiny, then let it cure for 24 hours.

FINISHING TOUCHES

Wet-sand the surface a final time with 600-grit sandpaper followed by 1,200 grit. The 600-grit paper will give the surface a smooth and uniform finish, and the 1,200 grit will remove any deep scratches.

Rub the surface with an automotive polishing compound until it has a "cloudy" finish. The final shine is produced by liquid silver polish. Simply rub it over the surface until the finish is bright and scratch free. At this point, the resin is still a little "soft." After it has cured for a couple of weeks, it will get very hard but not brittle, and it will not crack.

There you have it-a show-quality, very durable, maintenance-- free finish on a boat that won't leak! Once all the deck fittings are in place, wax the surface with a good-quality car wax, and you're ready for countless hours of maintenance-free sailing.

Dan Parson's Products, 11809 Fulmer Dr., N.E., Albuquerque, NM 87111; (505) 296-2353.

Dumas Products Inc., 909 E. 17th St., Tucson, AZ 85719; (520) 623-3742; (800) 458-2828; fax (520) 620-1329; dumasproducts.com.

Paasche Airbrush Co., 7440 W. Lawrence Ave., Harwood Heights, IL 60656-- 3497; (708) 867-9191; fax (708) 867-9198; paascheairbrush.com.

West Systems; distributed by Aircraft Spruce dr Specialty, 201 W. Truslow Ave., Fullerton, CA 92836; (800) 824-1930.

Fiberglass finishes for woods

Radio Control Boat Modeler, Aug 2002 by Tritle, Pat

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