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Types And Uses Of Epoxies
Marine epoxy has a wide acceptance in the industry, but it hasn't caught on in the wood shop as well as they should. Marine epoxy should be used quite often in place of other adhesives, especially when high strength and moisture resistance are factors. To properly use marine epoxy, one must first understand the basics. This is a two part adhesive consisting of a resin and a hardener, and is primarily divided into two classes: quick-set and slow-set, and these are additionally divided within these categories by the mixing ratios. Quick-sets of marine epoxy are typically 1:1 by volume, so that identical amounts are squeezed from syringes and tubes and mixed to a uniform color and consistency.
They usually achieve their strength in 10 minutes or less, and a full cycle within 24 hours, but they rarely reach the high strength that the slow sets do, and quite often retain some flexibility and resilience. Slow-sets of marine epoxy allow more open or working time, and can take up to 24 hours to cure. The advantages are superior strength, water resistance and gap filling capability. They don't take the same large amount of pressure as other adhesives. As a matter of fact, too much pressure can force the marine epoxy out of the joint ensuing in a bended or starved joint. The gap filling capability is no excuse for poor workmanship, but if a mistake is made, epoxy, especially marine epoxy can be very forgiving. The viscosity can be changed easily by the adding up of fillers such as sawdust, wood flour and talc. Probably the greatest advantage in using marine epoxy is the ability to join dissimilar materials. The adhesion factor is as great on metal as it is on wood, but non-porous materials need to be roughed up to augment the bond.