Synthetic resin with great strength and adhesive power
Epoxy resin is widely used in the boatbuilding and repair business as a tough gap-filling adhesive. It also forms high-grade laminates with glass fibers and other materials.Clear epoxy in thin consistency is used to seal wood and protect it from water penetration. It’s also used extensively in paints as a sanding filler and a barrier coat to help prevent osmosis in fiberglass hulls.For amateur use, epoxy is supplied as a liquid resin and a separate liquid catalyst, which must be mixed together to start a chemical cure. It’s particularly effective in repairs to fiberglass hulls, which are typically made from polyester resin, but when it’s properly applied, it forms an extremely strong bond that clings tenaciously to almost any surface. And while it is very strong, it stays flexible.Epoxy resin has revived interest in wooden boatbuilding because of its promise to reduce maintenance and extend the life of wooden hulls. The theory is that wood saturated in epoxy is immune to attack by dry rot and even by the various kinds of wood-boring mollusks that have always been attracted to wooden boats.The resin can be thickened and strengthened with various fillers that make gap-filling easier and compensate for lack of woodworking skill in amateur builders —a fact many traditionalists decry. Some critics believe epoxy has no place in wooden boat-building because it is sensitive to heat and starts to deform at temperatures commonly found on deck in hot climates. Most epoxy is not totally waterproof, either, and is rated only as water-resistant. It is particularly vulnerable to degradation by the sun’s ultraviolet rays and, therefore, must be protected by coats of paint or varnish loaded with ultraviolet filters.However, epoxy is a generic term for a whole group of resins, any of which might be formulated for special purposes such as better resisting heat or moisture penetration. The adhesive most commonly recommended for wood-to-wood applications is resorcinol, which is used extensively in outdoor- and marine-grade plywood.See also Adhesives.
