EPOXY PLUS OR GL-10 AS A STRUCTURAL ADHESIVE
If you are building one of our larger designs or working in temperatures below 70°, we recommend using our GL-10 epoxy adhesive. GL-10 will cure at temperatures as low as 35°, and even harden on damp wood (Epoxy-Plus will not). We should add at this point, however, that even though GL-10 and some other epoxies will set at very low temperatures, we do not recommend it be used at temperatures much below 50°F. Epoxy becomes too thick at lower temperatures, and is difficult to mix properly, and will not penetrate deep enough into the grain of the wood for maximum holding power. GL-10 has a working pot life of approximately 1 hr. This gives you a longer period of time between mixes and is ideal for working on larger projects where more time is required to install and fit some of the larger wooden parts.. Thickener can be added to Epoxy-Plus, making it a very effective glue which is sometimes preferable if you are only ordering a small amount of material. If you are laminating two sheets of plywood together we would then recommend using the Epoxy Plus without adding thickener, instead of our GL-10, as the lower viscosity will allow the panels to fit tighter together. GL-10 should be used in high stress areas such as laminating a cross beam for a trimaran design which would be under continued high stress. GL-10 would provide the holding power needed for this type of construction. When gluing your pre-coated plywood panels or frames use only Epoxy-Plus or GL-10 as resorcinol as any other type glue may not bond properly to the epoxy coating.
FINISHING AND PAINTING
After Epoxy-Plus has been applied and had sufficient time to harden (one week or more at 70°), you are now ready for painting and finishing. A light or heavy sanding should be done depending on how smooth the final application turned out. If heavy sanding is required use 80 grit wet/dry sandpaper. It is best to use the paper wet, and if you put a drop of detergent in a bucket of water it will help to keep the abrasive cutting at maximum efficiency. After the coarse sandpaper is used for cutting down any runs or sags you can then use 120 wet/dry sandpaper for final finish.
While many types of paint can be applied over Epoxy-Plus, it is important to test the paint you selected to see that it dries and adheres properly. We have found that Polypoxy paint by Pettit is one of the better and moderately priced paints that bonds well to Epoxy-Plus. Polypoxy is a two-part epoxy paint available directly through Clark Craft.
A CLEAR FINISH
All epoxies, if left unpainted over a period of time, will become dull and cloudy. If you would like to preserve the natural wood finish after the Epoxy-Plus has been applied, wait one week and lightly sand the surface. We have found that if a good quality marine spar varnish with an ultraviolet light inhibitor is applied over Epoxy-Plus this will preserve the clear finish for about 3 to 4 years. A second coat of varnish should then be applied. Due to an accumulative effect with each coat of varnish, the second coat should last from 5 to 6 years. Unlike painting varnish directly over a standard wood finish, the varnish will not crack and peel off after a couple of years due to the stabilizing effect of the wooden parts pre-coated with Epoxy-Plus. We suggest using EasyPoxy High Build Varnish listed in this site.
COVERING WITH FABRIC
Though it is not necessary to use fiberglass cloth when using Epoxy-Plus, we recommend using it for additional protection. A light layer of treated glass cloth adds a high degree of protection as it increases both abrasion and impact resistance of the laminate by a substantial amount. It also prevents fir marine plywood from checking, especially on horizontal surfaces. We also recommend using glass cloth in any high traffic area such as along the gunnel, floor, in the aft cockpit, etc. It is not necessary to use glass cloth in the bilge of the boat, inside the cabin or under the decks, as the Epoxy-Plus coating itself is excellent for that purpose.
CLEANING HANDS - TOOLS - ETC.
When using Epoxy-Plus resin keep the material off your hands and clothing as much as possible. Some people are allergic to almost anything, and initial or prolonged exposure could result in a skin rash, or other symptoms. To minimize exposure, use disposable gloves. If you get any epoxy resin or hardener on your skin wash it off as soon as possible. A good product to use is Fast Orange hand cleaner.Do not use solvents as they tend to dry out the pores of the skin and increase irritation. We recommend using disposable brushes or rollers, however if you need to clean tools, you can use lacquer thinner or acetone.
The shelf life of Epoxy-Plus and GL-10 glue at room temperature is about 1 year. Should the resin side of the Epoxy-Plus harden or crystallize, which may occur when subjected to cold temperatures, simply set the open container in a bucket of hot water, about 140°, for about 30 minutes. After it returns to liquid, stir thoroughly. Repeat if necessary and then allow to cool down. It should then be ready to use without any ill effects. Epoxy-Plus should never be used over wet or damp timber as you will lock the dampness in the wood and blisters may occur when the wood is placed in extremely hot temperatures . Although Epoxy-Plus is designed for temperatures above 70°, should the temperature drop after your project has been completed, the material will eventually harden. If you want to use Epoxy-Plus as a glue with a filler and the setting time is not important, it can be applied at temperatures down to 60° but it will take 4 to 5 days before the material does harden.
Tiny air bubbles may appear after the first cost of Epoxy-Plus has been applied to some hard woods. If this happens, lightly sand the area and apply a second coat. This problem should not recur as the pores in the wood are sealed by the first coat.
ESTIMATING MATERIALS TO ORDER
In order to determine the amount of Epoxy-Plus to order you must estimate the number of square feet to be covered. If you are building from plans or one of our complete boat kits you can calculate the amount of Epoxy-Plus needed in the following manner. Determine the number of sheets of plywood listed on your plan set or if building from a precut kit, a close estimate can be made in the following manner. For the precut side and bottom planking supplied in the kit, you must determine the length and the average width of each panel, multiply the length times the width arriving at the square footage per side, now double this figure and you will have the amount of area to be covered on your pre-cut panel . For plans and patterns, if the bill of material indicates three sheets of 4' x 8' plywood (thickness does not matter) you will use 32 square feet per side. This figure should then be doubled for a total of 64 square feet of area to be coated, both sides of each sheet of plywood. If there are three sheets of plywood indicated on this particular set of plans, you would have to multiply 64 times 3 which would equal 192 square feet to coat all three panels both sides.
As one gallon of Epoxy-Plus will cover about 140 square feet (for the recommended two coats), you would need about one and one-half gallons of Epoxy-Plus.
Now the remainder of the timber parts, such as the frame, keels, girders, battens etc., will have to be f igured and unless you are a whiz at calculating all these small measurements, an easy way to arrive at the approximate material needed is as follows. After the parts have been completely cut, ready to assemble or supplied from one of our complete boat kits, lay them out on the floor and bunch them up together as tightly as possible. Try to keep them in a square or rectangular shape so that it will be easy to multiply the length times the width and arrive at the total square surface for one side. As you did with the sheet of plywood, simply double the squared figure, this will give you total coverage for both surfaces. Unlike the plywood, you will have to take into consideration the edges as there are numerous edges to be coated, in some cases the building timber is an 1" to 1-3/4" thick. Here again a good estimate can be made by simply adding about 10% to the total squared figure.
We should mention at this time, after you determine the total amount of Epoxy-Plus to order, that you should add an additional 15% for waste.
One gallon of Epoxy-Plus will cover about 140 sq. ft. for the recommended two coats. The first coat covers about 225 sq. ft. per gallon, the second coat covers 350 sq. ft. If using fiberglass cloth, one gallon will cover about 45 sq. ft. for the required three coats.