Final Fairing & Finishing - WEST SYSTEM Epoxy

Figure 5 Use a spreader to apply fairing compound, and
slightly overfill the area. Shape the mixture to blend with
the surrounding contour.
small areas can often be judged by eye. When filling voids over ½" deep, it’s best to apply
the mixture in two or more layers to avoid excessive heat build up from the exothermic
curing reaction. Apply the second layer after the first layer has partially cured.
5. Use a batten to help shape larger areas. After slightly overfilling the area with a
spreader, slowly drag a batten across the filled area while bending it to the contour of
the surrounding fair areas (Figure 6). A slight “Z” or back and forth motion of the batten
can help to reduce the drag of the fairing compound. Allow the fairing compound
to cure thoroughly before sanding.
6. With the application of the fairing compound, low areas have now become high areas.
Sand these areas down to fair using the techniques for overall fairing. Continue to
check for fairness as you sand.
7. Fill and sand any low areas you find as many times as necessary until you are satisfied
with the overall fairness. When refilling areas, it is not necessary to re-coat the surface
with unthickened epoxy unless you’ve sanded through the first coating into the
original surface.
Notched trowel method
Figure 6 On large areas, use a batten to shape the
compound after applying it with a spreader.
Final Fairing 6
When fairing large areas that require a lot of filling, such as a steel or aluminum hull, it
may be easier and more economical to divide the process into two stages. The notched
trowel method helps to eliminate much of the sanding time required during the early
part of the fairing process by reducing the volume of fairing compound to be sanded.
The first layer of fairing compound is applied with a notched spreader to leave a pattern
of ridges. Before starting the procedure, use a batten to determine the depths of
the areas to be filled and cut the length of the notches in the spreader to match the
deepest area.
1. Be sure surfaces to be coated are clean, dry and sanded. Clean contaminated fiberglass
or metal surfaces with solvent before sanding. Sand or grind metal surfaces with a
coarse grit to remove oxidation and provide a texture for the epoxy to key into.
2. Wet out the surface with resin/hardener mixture (Figure 4). Coat the entire surface or
repair area at this time. To avoid sagging, allow the wet-out coat to gel before applying
the fairing compound. Sanded epoxy surfaces do not need to be wet out.
3. Prepare a fairing compound with epoxy and either 407 Low-Density or 410
Microlight filler. Dispense no more than 1/4 of a pot full of resin/ hardener to allow
room for filler. Mix the resin/hardener together thoroughly. Stir in filler until it
reaches a stiff, peanut butter consistency.