REPAIR INSTRUCTIONS USING FIBER GLASS MATERIAL
FIBER GLASS TYPES
HAND LAY-UP TYPE
In the past, most fiber glass parts have been made from
a hand lay-up type fiber glass. This material is made of
woven fiber glass cloth which has been impregnated with
a molding resin and molded to a desired shape. Much of
the manufacturing process is done by hand as the name
SHEET MOLDING COMPOUND (SMC) TYPE
Currently, various parts are made from a newer type
fiber glass called Sheet Molding Compound (SMC).
This compression molded fiber glass differs from hand
lay-up fiber glass in that it is made from a resin molding
compound to which short or shredded glass fibers have
been added. The resulting plastic mass can be
compression molded to any desired shape without using
cloth as is used for the hand lay-up type.
RESIN TRANSFER MOLDING (RTM) TYPE
A third kind of fiber glass called Resin Transfer Molding
(RTM) is also being used. This type fiber glass is similar
to both hand lay-up and SMC types in that it uses a glass
mat or cloth in a closed mold to which the resin molding
compound is added. A room temperature catalyst
(curing or hardening agent) is also used. This type fiber
NOTE - The external surface appearance of all three
types of fiber glass material Is similar. However, the
hand lay-up type material Is rough textured on Its Internal
surface (back side) while "SMC" and "RTM" materials
FIBER GLASS REPAIRS
All types of fiber glass repairs, whether cosmetic or
structural, are covered on the following pages. The
procedures are illustrated using the Sheet Molding
Compound (SMC) type fiber glass. These procedures
are also applicable and recommended for repairs to the
hand lay-up type and Resin Transfer Molding (RTM) type
NOTE - The Illustrations used in this write-up are typical
and do not necessarily represent a particular part or
Most of the hand and power-type tools (Figure 1)
required to repair fiber glass or sheet metal body
components with fiber glass material are common tools
that can be found in any automotive body repair shop
Figure 1. - Tools Required
Pneumatic or electric drill with sanding
attachment, burr bits and tapered bits.
Sandpaper and sanding discs (24-80 grit and
360- 600 grit).
Electric sander and sanding block.
Sabre saw or hacksaw.
Assortment of clamps.
Assortment of files.
Plastic separating film.
Safety goggles & respirator mask.
Xylol, acetone or equivalent solvent.
Observe the following when making repairs with fiber
Avoid spilling the resin or hardener on skin or
clothing. If this occurs, remove with paint thinner
or denatured alcohol. Then wash with soap and
water. If the mixture contacts the eyes, flush
thoroughly with water Immediately. Continue
flushing for at least 15 minutes and contact a
physician as soon as possible.
In some cases, some Individuals may have skin
sensitivity to the use of these materials.
Because of this, protective creams can be
applied to the hands to guard against Irritation.
When protective creams are not available,
rubber gloves may be used to protect the hands.
The gloves can be removed quickly leaving the
hands clean for other work.