closely woven one. Woven fabrics are usually identified
Any chemicals or solvents should be handled with
by a style number that refers to a specific cloth or a
caution. The repair of reinforced plastics is no excep-
tion. Cutting and grinding of reinforced plastic lami-
certain weave, weight, and thickness. For example,
style #1000 cloth identifies a plain weave cloth that
nates generates a fine dust that irritates the skin and
eyes. Inhalation of the dust should be avoided.
weighs 10 ounces per square yard and is 0.013-inch
thick. Woven fabrics are coated with a finish to improve
The following safety precautions should be fol-
the bond between the glass and the resin. The third type
of glass reinforcement, which is gaining popularity
1. Wear protective gloves, goggles, and respirators
because it is cheaper than cloth and builds up the thick-
provided with the kit. If available, apply a protective
ness of a laminate faster, is called woven roving. This
hand cream to all exposed skin areas.
type of reinforcement resembles a hand-woven pot-
2. Avoid contact with the eyes, skin, or clothing. If
holder both in weave and appearance. A commonly
these materials contact the skin or eyes, immediately
used type of roving is about 0.040-inch thick and weighs
flush them with water for 15 minutes. If the eyes are
24 ounces per square yard. Of the three types of rein-
involved, obtain medical attention.
forcements, the woven fabric is the easiest to handle and
3. When working in confined spaces, be sure there
the most dependable for repair work.
is adequate ventilation. Where such ventilation cannot
Two types of resins are usually used for repairing
be provided, organic respirators are required for
reinforced plastics. The first is a polyester, which may
protection against fumes.
be obtained in a wide range of viscosities. The consis-
4. If clothing becomes contaminated, remove it
tency of the very high-viscosity resin resembles heavy
and wash it thoroughly before reuse.
molasses, while that of the low-viscosity resin is like
5. Always wash exposed skin areas thoroughly
water. Usually, the low-viscosity resin will saturate or
when you are finished working.
"wet-out" a glass reinforcement faster, but it will also
drain more rapidly on a vertical surface. This drainage
6. Keep chemical containers clearly labeled and
may be undesirable in some applications and may be
tightly covered when they are not in use. When mixing
minimized by the addition of a small amount of a finely
a polyester resin, NEVER mix the catalyst and
divided silica. A highly viscous resin may be thinned
accelerator directly together or an explosion may result.
by the use of a small amount of styrene. Many resins are
Always mix chemicals according to instructions.
available commercially that have been specially com-
7. Do not smoke or work near hot surfaces or open
pounded to the proper viscosity for repair use.
flames while using these materials.
Polyesters are also extremely versatile in cure
(hardening) characteristics. The addition of a small
amount of an organic peroxide catalyst in a powder,
paste, or liquid form, and an accelerator will cause a
Many factors determine how closely the strength of
cure to occur at ambient temperatures above 50°F with-
a reinforced plastic repair will resemble the strength of
out the application of heat. The working life (time
the original laminate. Workmanship, repair techniques,
within which the resin remains liquid and usable) and
the glass reinforcement, and resin all play an important
cure time may be varied by adjusting the proportions of
part in any repair. Reinforced plastics are easy to repair
the catalyst and accelerator used. The resin supplier will
if you have a knowledge of materials used and proper
generally provide information on resin formulations.
Some resins are supplied with the accelerator already
Three types of reinforcement are most frequently
added, thus only the addition of the catalyst is required.
used--singly or in combination--in glass-reinforced
Temperature greatly affects the cure time of polyesters;
plastic laminates. The cheapest and weaker type, ran-
the higher the temperature, the faster they will cure.
dom glass mat, consists of chopped glass fibers that are
Polyesters also have a limited storage life of about 6
either lightly bonded together with a small amount of
months to a year. Standing in storage causes them to
binder resin, or mechanically stitched into a random,
gradually thicken until they become unusable even
jackstraw arrangement. These mats may be obtained in
though the catalyst has not been added.
weights from 1/2 ounce to 3 ounces per square foot. The
strongest and most expensive type is woven glass cloth.
Epoxy, the second type of resin that may be used
It is available in a wide range of weaves and styles,
in reinforced plastics repair at room temperature, is
varying from a coarse, loosely woven fabric to a fine,
widely recognized as an adhesive for a great variety