Epoxy has arguably become the standard adhesive for use aboard boats. While 3M's 5200 still reigns supreme as the king of adhesive sealants, for pure adhesion it is hard to beat epoxy.
Whether you are mounting hardware, bonding parts together, filling holes or making other repairs and additions, modern epoxy systems allow the user to precisely tailor the consistency and characteristics of the epoxy to fit the job. For example, you can control whether it sets quickly or slowly, or whether it is viscous or runny.
That gives the user a great deal of control, making jobs far easier than they once were.
There are many epoxy systems to choose from. The best strategy is to select one and stick with it. The truth is that I'm an epoxy junky. It's a powerful tool that can change the way you approach a myriad of onboard projects, and it is not difficult to learn. In fact, if you can make a decent peanut butter and jelly sandwich, you can learn to effectively use an epoxy system.
What follows is a primer on how epoxy works, and some tricks and tips on how to make it work for you. As always, practice makes perfect. Start with small projects and gain skills over time. Also, cultivate good habits when it comes to understanding the materials you are using and practicing proper safety precautions.
When the big jobs come, you'll be ready.
HOW IT WORKS
Most epoxy systems involve mixing two key ingredients: the resin and the catalyst, or "hardener." The result when the two are mixed is a thermosetting chemical bond that uses heat produced by the mixture to enact the curing process. By varying the type of hardener – or adding in different chemicals – you can change the properties of the epoxy and how long it takes to cure.
The number of projects facilitated by epoxy is endless. For example, I think epoxy is the best product for bonding things to cured polyester fiberglass such as boat hulls and structures. Polyester resin is not a good choice as it doesn't develop strong secondary bonds; it isn't a good adhesive. If you are repairing or adding to a fiberglass boat, I recommend epoxy.
Along these same lines, epoxy can be used to barrier coat a fiberglass hull. Polyester-based hulls are sometimes prone to osmotic blisters. One way to cure blisters is to pop them open, let them dry completely, fill them with epoxy and filler, and then fair them smooth. Once this is done, epoxy resin and barrier coat additives can be used to build up a waterproof barrier on the underwater portion of the hull. It usually takes about five to six coats of epoxy to produce an effective barrier.
Many boaters are also using epoxy as a base for a tough, long lasting varnish job. After the teak or other wood is sanded to a smooth finish with a uniform color, epoxy is brushed on. Three coats of epoxy are generally used, with each coat sanded before the next is applied. This forms a strong stable base that won't crack. The wood will look great at this point, but you aren't finished yet. Remember that epoxy has little or no resistance to UV rays. To provide the needed protection, a minimum of three coats of a good UV-resistant varnish should be applied.
BUILDING YOUR TOOL KIT
Personally, I have always used West System epoxies and additives from Gougeon Brothers. That isn't to say they are the only epoxy suppliers, or even the best. I just started out using their products and never switched. System Three, Raka, Mas and FGCI also make fine products.
Pick one you like and learn to use it. I would strongly suggest that once you choose an epoxy supplier, that you use all their products. Switching back and forth between brands is a sure recipe for trouble.
Once you have started purchasing those epoxy supplies, organize them for ease of use. I move my epoxy and supplies back and forth between the home shop and my project boats. To do this, I use cheap plastic tool carriers from the local home improvement store, with a central handle with a compartment on each side. I can carry a quart of epoxy with hardener, several small cans of additives, gloves, small mixing containers and mixing sticks. The carrier is easy to transport and keeps you from forgetting anything important. I refill the smaller containers from larger containers at the shop when necessary.
The cans are fitted with pumps to dispense the resin and hardener. West epoxy is mixed at a five-to-one ratio: five parts of resin to one part of hardener. Other systems may use different ratios. No matter which products you use, epoxy pumps are designed so that one stroke of each pump automatically dispenses the right ratio of epoxy and hardener. The pumps are something you usually have to purchase extra, but the expense is worthwhile. Buy the pumps. Struggling to dispense the epoxy and hardener into graduated cups is time consuming and frustrating. Buy the pumps!
You can purchase epoxy mixing pots at marine stores. These will last several mixing cycles, because you can flex the pot and pop out the hardened resin. Eventually, though, they get brittle and crack. I have better luck with margarine containers. They are free (if you use the margarine) and seem to be a little sturdier than the epoxy pots.
