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THE
BASICS FOR BUILDING FIBERGLASS MOLDS
The
purpose of this document is to give step-by-step recommendations
for producing various plugs, molds and masters, and to standardize
some of the terms used to determine the differences between
a plug, a mold and a master. While these recommendations are
not the only way of performing these tasks, the guidelines
herein have been proven in pattern and mold shops over many
years.
A
plug is generally comprised of wood or existing fiberglass
pieces, clay or hard fillers for the radii, and will be both
dimensionally correct and shaped exactly as the finished fiberglass
unit would appear. After preparing the surface of the plug
for the application of polyester tooling gel coat and layers
of fiberglass laminate, a reverse image of the mold is built
and removed from this plug. The mold is then prepared for
a fiberglass master in the same fashion as the plug was prepared
for the mold. The plug produces the mold, and from the mold
comes a fiberglass master. This master will then produce molds
that will produce finished fiberglass units.
Plugs
are constructed in the shape of the desired finished product.
When a plug requires precise tolerances of dimensional stability
or intricate design lines, these are generally shaped or formed
by the plug-builder to the satisfaction of a blueprint or
an artist's conception of what the finished fiberglass product
should look like. As a rule, plug-builders insist that the
plug's finished surface have the esthetic appearance of a
finished, marketable fiberglass unit.
For
example, if you were to build a plug for the deck of a boat
or a truck cap, you would be utilizing a quality grade of
plywood for shaping the flat areas and fillers for the radius
areas. You would also make sure that the finish on the completed
plug would be as smooth and shiny as the fiberglass part to
be produced from the mold made from this plug.
Remember:
The mold is a mirror image of the plug, and the finished part
will reflect the surface of the mold. Concentrating efforts
on the plug will enhance every stage thereafter. One of the
most successful ways to achieve high gloss, mirror-like finish
over wood and other substrates is to use high polyester paint
systems such as Fourseal
and Fourgard.
For
more information on Fourseal
and Fourgard please contact one of our many customer service
centers.
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