The Gougeon Brothers on Boat Construction - WEST SYSTEM Epoxy

Chapter 4 – WEST SYSTEM ® Products 29
410 Microlight is the ideal low-density fairing filler
for creating a light, easily-worked fairing compound
especially suited for fairing large areas. Microlight
mixes with greater ease than 407 Low-Density Filler
or microballoons and is approximately 30% easier to
sand. It feathers to a fine edge and is more economical
for large fairing jobs. It is not recommended under
dark paint or other surfaces that could be subject to
high temperatures. <strong>The</strong> mixture cures to a light tan
color.
Additives are blended with mixed epoxy to alter the
physical properties of epoxy when used as a coating.
Additives can be used to alter the color, abrasion resistance,
or moisture resistance of cured epoxy.
420 Aluminum Powder provides limited protection
from ultraviolet light in areas that will not be protected
with other coatings. It can be used as a base for subsequent
painting. 420 will increase the hardness and
abrasion resistance of the coated surface and improve
its moisture resistance. Mixtures cure to a metallic gray
color.
423 Graphite Powder is a fine black powder that can
be mixed with WEST SYSTEM epoxy to produce a lowfriction
exterior coating with increased scuff resistance
and durability. Epoxy/graphite is commonly used as a
bearing surface and as a coating on rudders and centerboards
or the bottoms of racing craft that are dry sailed.
It does not provide antifouling qualities. Graphite
powder can also be added to epoxy thickened with 404
High-Density Filler for use in teak deck construction to
simulate the look of traditional seams and to protect
the epoxy from sunlight. Mixtures cure to a black color.
501 White Pigment and 503 Gray Pigment are
epoxy-based liquid colorants used to tint the epoxy
mixture to provide an even color base for the final finish
system. <strong>The</strong> colored surfaces also tend to highlight
flaws and imperfections. Cured, pigmented epoxy
surfaces are not a final finish surface but require an
additional paint or UV filter coating for ultraviolet
protection.
For colors other than white or gray, powdered pigments
(tempera paint, colored tile grout, aniline dyes) and
universal tinting pigment can be added to the epoxy
mixture. Acrylic paste pigments (available from marine
chandleries) may also be used to tint the mixture as long
as they are specified for use with polyester or epoxy
resin. 423 Graphite Powder will color the epoxy black
or impart darker shades to colors.
Generally, coloring agents can be added to the mixed
epoxy up to 5% by volume with minimal effect on the
cured epoxy’s strength. Always make test samples to
check for desired color and opaqueness and for proper
cure. None of these coloring additives provide UV resistance
to the cured epoxy, so limit their use to areas not
exposed to sunlight unless additional UV protection is
applied.
860 Aluminum Etch is not an additive but a twostep
surface treatment for aluminum that significantly
improves WEST SYSTEM epoxy’s adhesion to aluminum
for bonding and coating.
WEST SYSTEM Reinforcing Materials
Unidirectional Carbon Tapes are used for selective
reinforcement to improve tensile strength and stiffness in
one direction while adding minimum thickness and
weight. Fiber bundles are held in place by a polyester
fill thread for easy handling and wet out.
Unidirectional Glass Tapes are also used to add
strength in one direction, but with less stiffness than
carbon fiber. <strong>The</strong>y are also easy to handle and wet out.
Biaxial Tapes are a non-woven E glass fabric. Two layers
at a ±45° fiber orientation are held together by a light
stitching. Flat, non-crimped fibers yield reduced printthrough
and higher stiffness than woven fabrics. Biaxial
Tapes are ideal for repairs, tabbing, and reinforcing.
Glass Tapes are versatile 9 oz (305g/m2 ) woven fabric,
ideal for reinforcing chines, hull/deck corners, and
similar structural applications. When bonded with
WEST SYSTEM epoxy, they provide additional tensile
strength to resist hairline crack development and
abrasion. <strong>The</strong>y have bound edges for ease of use and are
available in a variety of convenient widths.
Biaxial Fabrics are non-woven E glass fabrics, with
two layers, ±45° fiber orientation. <strong>The</strong>y are used for
composites, repairs, and reinforcing and will achieve a
high fiber-to-resin ratio with hand wet-out. <strong>The</strong>y are
also available with a lightweight, chopped-strand mat
backing.