WHICH RESIN ??
EPOXY vs. POLYESTER vs. VINYLESTER
of the "one size fits all" approach.
More than 95% of all boats, truck & car bodies made of
fiberglass are made primarily of E-glass,
orthothalic polyester resin and isothalic polyester
gelcoat. Items constructed with these materials
should be repaired with the same or compatible
material. LBI's 301 Orthothalic Polyester Resin is
good choice for most repairs. It provides a chemical bond
to the existing laminate with similar
strength & flexural characteristics.
Orthothalic polyester, isothalic polyester and vinylester resins
are compatible, they all have styrene
(commonly known as the "fiberglass smell") and
chemically bond to one another.
If higher strength, bond and water resistance are required (such
as keel, rudder repair, or outboard
transcom replacement) use LBI's 302 Isothalic Polyester
For the highest bond strength, bond strength and water resistance
use LBI's 901 Vinylester Resin.
Vinylester is essentially a styrene modified epoxy resin.
It gives excellent strength, rigidity, adhesion,
water and chemical resistance.
Keep in mind...
* Epoxy adheres to wood much better than polyester does. To
cover wood, a laminate using
epoxy resin and 10 oz. cloth will yield a much better job
than 10 oz. cloth and polyester resin.
The epoxy / cloth laminate is comparable to using
polyester resin with 3/4 oz. mat and 10 oz. cloth.
However, the epoxy laminate requires much less labor to
* A polyester laminate job is somewhat less expensive in material
costs than an epoxy laminate
project of the same size.
* Fiberglass mat cannot be used with epoxy because the binding
material in the mat will NOT
dissolve in epoxy resin.
* Either mat, cloth or woven roving may be used with polyester
* Since mat sticks much better to wood than cloth does, always
make mat your first layer against the
wood to be covered in a polyester laminate
* We recommend using a layer of mat between layers of cloth for
maximum adhesion between layers.
PREPARATION FOR COVERING WOOD WITH FIBERGLASS AND
POLYESTER OR EPOXY
NOTE: If working with old wood, remove all
paint and foreign material from surface.
Step 1: Sand surface
with 60 or 80 grit samdpaper to rough-up surface.
Step 2: Brush or roll
on a primer /
saturation coat of catalyzed polyester resin thinned 25%
acetone or styrene. Epoxy resin should be thinned
25% with 1271 Epoxy Solvent.
(Use either polyester or epoxy for a job. Never mix the two together).
Step 3: Sand lightly
with 60 or 80 grit sandpaper to de-burr the surface. Be
very careful not to sand
through the primer /
Step 4: You are
now ready to proceed with the lay-up method you've
* No laminating project should be started without
having a solvent handy for clean up. Use acetone
with polyester resin and 1271 Epoxy Solvent with epoxy
* Keeping mixed resins, particularly epoxies in a wide,
shallow pan, such as a roller pan, will
increase the pot life. This allows the mixture to
shed heat and prevents an accelerated reaction.
* Use caution when laying-up glass in direct sunlight because it
can greatly decrease working time.
* Remove air bubbles and wrinkles from uncured laminate by using
an aluminum or nylon air bubble
roller. The air is driven from the uncured laminate
into the fins of the roller thus yielding an even,
bubble free surface.
* Our epoxies, as with most all epoxies, require 5 to 7
days at 70° F
to achieve full cure.
SAFETY AND HANDLING
* Keep all resins, hardware and solvents
out of the reach of children.
* Always work in well-ventilated areas.
* Safety goggles, gloves and respirators should always be worn
when handling resins, hardeners
* Harmful if swallowed - consult a
* If polyester or epoxy resins or hardeners should splash in your
eyes, rinse eyes repeatedly water
and call a physician immediately.
* Never use or store resins, solvents or hardeners near open
flame. Do not smoke when working with
* We strongly recommend that an organic vapor respirator be worn
when using polyester or epoxy
resin. However, it is mandatory to wear a respirator
when working inside a mold or in confined
areas, even though good general ventilation is
* Dust masks and safety goggles should always be worn when
grinding or sanding cured fiberglass
* Uncured resin spills should be absorbed material. The
surface can then be cleaned immediately with
hot water and detergent.
* A clean, neat, well-organized work area is generally a
safe work area.
FIGURING HOW MUCH RESIN AND GLASS YOU
Use the following Resin Chart as a rule
of thumb guideline to determine resin coverage.
Resin to glass usage for polyester and epoxy are very
Gallon of Resin Wets Out:
|18 oz woven
|24 oz woven
(50" wide material = approx. 12 sq. ft per liner
Example for figuring amount of fiberglass needed...
Mr. Smith wants to put an epoxy and glass covering of 1
layer of 10oz. cloth and 1101/2102 epoxy on
a cabin top of his boat. The cabin top is 9 ft. wide by
10ft. long. The total area to be glassed is 90 sq.ft.
The cabin top width is 108 inches. Using 38 inch
cloth, Mr. Smith needs three 10 ft. pieces.
(108 in. ÷ 38 in. cloth = 21.84 or 3 pieces).
Always consider the width of the cloth plus an overlap allowance
at the seams. (We recommend
overlapping all seams 1 to 4 inches). Since Mr. Smith will
be using 90 sq. ft. (three 10 ft. x 38 in. pieces)
of material, he should refer to the resin chart to determine
the amount of resin he will need. In this
example, Mr. Smith will need one and one half (1 1/2) gallons of
resin to cover the cabin top of his boat.
Catalyst Usage for 301, 301W, 302, 303 & 305
(Polyester), and 901 (Vinylester) Resin
& 302 ISO
5-15cc 321 MEKP per qt. resin
901 & H1297P Vinylester
10-30cc 391 MEKP per qt. resin
* In cool weather (55-60 °F) catalyze 301 & 302 in the mid
to high range (10-15cc) & H197P (20-30cc)
* In hot weather (75-90 °F) catalyze 301 & 302 in the low to mid
range (5-10cc) and 901 & H197P (10-20cc)
* REMEMBER THE MORE CATALYST YOU USE AT A GIVEN TEMPERATURE THE
FASTER THE CURE!
* NEVER CATALIZE BELOW THE MINIMAL RECOMMENDED QUANTITY!
* BE ORGANIZED AND HAVE ALL YOUR TOOLS AND SUPPLIES READY!
RESIN WAITS FOR NO ONE!
Cure Time- The amount of time required for a
catalyzed resin to reach approximately
of its ultimate strength. Full cure may take up to 7 days,
at 70 ° F.
Fair- To fill
and sand an irregular surface to make it smooth and
reinforcing material comprised of fine glass fibers.
A substance which when added to resin in the proper
causes the resin to cure and turn from a liquid to a solid.
Laminate- The process
of saturating layers of fiberglass fabric with
resin; a properly saturated layer
of reinforcing material.
Lay-up- The process
of applying layers of fiberglass fabric and resin in a mold or on
a surface, i.e. a
Pot Life- The amount
of time from mixing the catalyst into the resin until it begins
to gel in the
Leveling- When poured onto a horizontal surface
liquid flows out flat, similar to oil.
Thixotropic Powder- A
powder which, when added to a liquid such a resin,
creates a non-sagging,
liquid with characteristics similar to those of latex paint.