The Epoxy Book

Welcome to The Epoxy Book by System Three Resins, Inc.

Here you will find a wealth of information regarding the use of epoxy in boat building, wood working, rot repair and more.

The best way to learn about epoxy resin products is to use them. You have to practice, just as you would if you were learning to snowboard, sail or play the guitar. The best and least expensive way to practice is to get The SilverTip Epoxy Trial Kit, some cheap lumber and try some of the techniques outlined in this book. Nothing beats hands-on learning. Even experienced epoxy users benefit from practice when trying something new. If you get stuck on something, go to our website, become a member if you haven’t already done so, look in the FAQ’s, glossary, literature, product data sheets, or MSDS and see if you can find the answer to your question. If you contact us with a question we’ve already answered we will point you to the information rather than answer your question directly– you’ll learn more that way.

We select our resin and hardener raw materials with the health and safety of our customers in mind. However, it is not possible to make a perfectly safe epoxy resin system. These materials all have health risks, especially if improperly used. The primary hazard when working with an epoxy system is skin irritation leading to potential skin sensitization from prolonged and repeated contact. Most people who become sensitized are unable to continue working with epoxies without breaking out in a rash most commonly on the inside of the forearms and on the forehead above the eyebrows. The effect appears to be cumulative. That is, you might be able to get away with getting epoxy on your skin for a while, but it could catch up to you and you will be sensitized.

Thoroughly knowing epoxy resin chemistry is not necessary before using a System Three product, but having a rudimentary chemical knowledge will help you complete any project more effectively, avoiding pitfalls or surprises which may arise when using epoxy containing materials.

Measuring and mixing is really easy with most of our epoxy systems because they mix at a 2:1 or 1:1 volume ratio, but this doesn’t mean you don’t have to pay attention to what you’re doing. First, read the label or Technical Data Sheet to see what the correct ratio is for the product you are using. Customers will call our Technical Support line suggesting that something is wrong with the epoxy because it didn’t cure properly. We know of no situation where properly-mixed resin/hardener has gone bad or has been contaminated and wouldn’t cure. It always resolves that the batch was either improperly measured or insufficiently mixed in the user’s shop. Epoxy chemistry just will not allow it to work any other way.

System Three Resins began manufacturing and selling formulated epoxy resin systems to the marine industry in 1979. Our initial product (now called our General Purpose epoxy) took what we call the “chemistry set” approach. That is, for building or repairing wooden boats, one bought a low viscosity, clear resin and the appropriate speed hardener, along with powdered fillers, thixotropes, wood flour, microballoons and the like. The basic resin/hardener system was formulated to be able to coat wood and wet out fiberglass cloth when used right out of the container. With the addition of various dusty powdered fillers one could make an adhesive, filleting putty or fairing compound.

What follows is a brief description of the various epoxy product systems we offer along with suggested areas of use. Consult the individual Technical Data Sheets for each product for specific information. These are available online at www.systemthree.com, from your System Three dealer, or by calling us.

Epoxy resins are used and applied following one of four basic techniques. These are coating, fiberglassing, gluing, and filleting/fairing. Furthermore, the techniques are pretty much the same whether they involve new wooden boat construction, the repair of fiberglass boats, furniture building, bar top coating or dry rot repair.

Wood is often coated with epoxy to dimensionally stabilize it and provide a barrier which helps to prevent the passage of moisture. Silvertip Laminating Epoxy has a certain amount of flexibility and tough resilience built into the formulation. Because of this, a plywood panel could be coated on the bench, then bent into place without danger of the epoxy cracking. When working flat you’re not fighting gravity and the coated panel is easily sanded on the bench using a disc sander and foam pad. The sanded panels are then installed and are ready for painting. Coating a 4’x8’ sheet of fir plywood will illustrate this method:

Outside surfaces of boat hulls are usually epoxy/fiberglassed to create a thicker, stronger epoxy coating. This provides higher abrasion, impact and moisture resistance. In the case of most wooden boats, the purpose of reinforcing cloth is to strengthen the epoxy coating, not to reinforce the hull. Chines, keels, bow and transom corners are structurally reinforced with fiberglass tape and epoxy. Fiberglass tape has been judiciously used to great advantage by woodworkers to strengthen unseen edges of complex miter/bevel joints in panels.

Epoxies formulated for coating and fiberglassing are too thin to serve as gap-filling adhesives. They can be modified by the addition of thixotropes to form non-sagging pastes very useful as gap filling glues. These pastes can be further modified with the addition of microballoons to form putties for fairing and hole filling. Wood flour can be used to make filleting putty for stitch-and-glue boat construction. All these solid dusty additives are called fillers. Fillers change the flow and density characteristics of the epoxy system. Each filler changes the liquid resin and hardener in ways that make epoxy useful for other applications besides coating or fiberglassing.

The mixed viscosity of coating and fiberglassing epoxies is not high enough to make good gap filling adhesives. Thixotropic agents like silica thickener (Cab-O-Sil, Aerosil), plastic minifibers, and wood flour are used to thicken the epoxy and change the flow characteristics. These fillers will turn the epoxy from translucent to opaque depending on the type and amount used. Silica thickener and plastic minifibers make the epoxy whitish while wood flour turns it reddish-brown. Silica thickener makes a smooth material while epoxy thickened with plastic minifibers or wood flour will be coarse. Microballoons and microspheres should not be used in adhesive formulations as they reduce tensile strength.