Fiberglass Tips

by John Doe
(New Orleans)

Fiberglass, a material made from threads or fragments of spun glass, comes in different forms. As a building material, it is molded into hard panels; for shaped objects, it is matted or woven into a fabric, which is then bonded with resin. Preformed fiberglass panels are easy to work with and can be cut with a saber saw fitted with a fine-tooth blade. For an outdoor project such as a patio roof heavyweight corrugated or ridged panels are best; for indoor use or where rigidity is not necessary, use lighter flat panels.

Supplies for building with the panels, such as sidewall flashing and corrugated closure strips, are also available. To clean the panels, hose them with water; if they discolor, apply a re-finisher recommended by the manufacturer. Fiberglass panels will not bear a person's weight; never attempt to walk on them. Fiberglass laminate is used to make shaped objects such as automobile bodies, boats, swimming pools, and hot tubs. Layers of fabric are bonded together with a liquid resin that cures with the addition of a catalyst, forming a tough, durable shell.

Holes up to 1/2 inch in diameter in fiberglass laminate can simply be filled with putty—a mixture of resin and filler. Larger areas of damage are repaired by patching with layers of fabric and resin. However, if you suspect that the damage may have affected the structural integrity of an object, consult a professional before attempting the repair. A repair patch usually consists of alternating layers of mat and cloth; in large projects, woven roving is some-times used. A successful repair depends upon choosing the correct fabric and resin; the chart on the facing page will help you determine the best combination for a particular repair. Polyester resin—used for most laminate repairs—is easier to work with and less expensive than epoxy. There are two types: Air-thy or tack-free, contains wax, which floats to the surface of the repair, sealing off the air and allowing the resin to cure with a hard surface. The other type, air-inhibited, cures to a tacky surface unless covered with wax paper or polyvinyl alcohol spray (PVA), which can be found at marine supply stores. The PVA i

s washed off with warm water after the resin cures. Fabric will bond better if you use air-inhibited resin for the inner layers of a repair: if you use air-dry resin for the outer layers, it will harden so that the surface can more easily be sanded. Epoxy resin cures hard, but slowly. It will bond well with many materials hut is more difficult to work with than polyester. If in doubt whether CO use epoxy or polyester resin for a repair, contact the manufacturer of the object or try a small test parch on -an inconspicuous spot. The outer finish coat of fiberglass laminate is gel coat, a specially formulated polyester resin. Wash the gel coat with detergent and water (or wipe it with a solvent such as acetone), and buff with wax to protect it. Scratches that do nor penetrate too far beneath the gel coat can easily be repaired with a mixture of gel coat and filler, often available in a kit at marine supply stores.

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