WHICH RESIN TO USE?? EPOXY vs. POLYESTER vs. VINYLESTER

GENERAL TECHNICAL GUIDE FOR RESINS and FIBERGLASS

• The majority of all boats, truck & car bodies made of fiberglass are made primarily of standard E-glass, an Orthothalic Polyester Resin and Isothalic Polyester Gelcoat.
• Therefore, items constructed with these materials should be repaired with the same or compatible material. LBI’s 301 Orthothalic Polyester resin is a good choice for most repairs. It provides a chemical bond to the existing laminate with similar strength & flexural characteristics.
• Ortho polyester, Isothalic Polyester and Vinylester Resins are compatible, they all have styrene (commonly known as the “fiberglass smell”) and chemically bond to one another.
• When higher strength, bond and water resistance is required (such as keel, rudder repair, or outboard transom replacement) use LBI’s 302 Isothalic Polyester Resin.
• To achieve the highest bond strength and water resistance use LBI’s 902 Vinylester Resin.
• Vinylester is essentially a styrene modified epoxy resin. It adds excellent strength, rigidity, adhesion, water, and chemical resistance.

 EPOXY WOOD COVERING LAMINATES

• Small Boats, Kayaks, Boat Decks: 3.5, 6, or 10oz Fiberglass cloth.
• Large boat hulls Structural covering: 1700 Biaxial, 1800 Biaxial
• Multiple layers can be used if a thicker laminate is desired.
• Additional layers can be added at chines, keel stem, etc. for additional strength or abrasion resistance.

POLYESTER or VINYLESTER WOOD COVERING LAMINATES

• Boat Decks: .75oz Mat and 10oz Cloth
• House or Commercial Boat Decks: 2 X 1.5oz Mat
• Large Boat Hull Structural Covering or Heavy Service Commercial Boat Decks: 5 Mat, 1708 Biaxial 1.5 Mat

OTHER HELPFUL HINTS

• To cover wood, a laminate using epoxy resin and 10oz, cloth will yield a much better job than 10oz cloth and polyester resin.
• The epoxy/cloth laminate is comparable to using polyester resin with .75oz mat and 10oz cloth however the epoxy laminate requires much less labor to fair.
• A polyester laminate job is somewhat less expensive in material costs than an epoxy laminate project of the same size.
• However, it requires more labor to fair.
• Fiberglass mat generally should not be used with epoxy because the binding material in the mat will NOT dissolve in epoxy resin.
• IT CAN BE USED ON FLAT LAMINATES WHERE THERE IS NOT A NEED TO BEND AND FORM THE FABRIC.
• Either mat, cloth or woven roving may be used with polyester or vinylester resin.
• Since mat sticks much better to wood than does cloth, always make mat your first layer against the wood to be covered in a polyester laminate project.
• 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

Prep:  If working with old wood, remove all paint and foreign material from surface.

Step 1:  Sand surface with 36 or 80 grit sandpaper to rough-up surface.

Step 2:  Brush or roll on a primer/saturation coat of catalyzed polyester resin thinned up to 50% with Acetone. Epoxy resin should be thinned 50% with 1271 Epoxy Solvent or MEK Solvent and let cure.

Step 3:  Sand lightly with 60 or 80 grit sandpaper to de-burr the surface. Be very careful not to sand through the primer/saturation coat.

Step 4:  You are now ready to proceed with the lay-up method you’ve chosen.

OTHER HELPFUL HINTS

• No laminating project should be started without having a solvent handy for clean-up. Use Acetone with Polyester or Vinylester Resin and with Epoxy use 1271 Epoxy Solvent or 1272 Denatured Alcohol.
• 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. Once the resin is spread on the lay-up the gel time will be much greater than Pot Life.
• Use caution when laying-up glass in direct sunlight because it will greatly decrease working time.
• Remove air bubbles and wrinkles from uncured laminate by using an aluminum or nylon Laminating (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 up 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, and solvents. Avoid contact with the skin.
• Harmful if swallowed – consult a physician immediately.
• If polyester or epoxy resins or hardeners should splash in your eyes, rinse eyes repeatedly with water and call a physician immediately.
• Never use or store resins, solvents, or hardeners near open flame. Do not smoke when working with these materials.
• We 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 provided.
• Dust masks and safety goggles should always be worn when grinding or sanding cured fiberglass laminate.
• Uncured resin spills should be absorbed with sawdust or other absorbent 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.
• Store resins in a cool area, though not lower than 70°F.

HOW MUCH RESIN and GLASS YOU WILL NEED?

Use the following Resin Chart as a guideline to determine resin coverage. Resin to glass usage for polyester and epoxy are very similar.

1 Gallon of Resin Wets Out:

      Material                        Square Foot

     .75 oz Mat                           64 sqft

   1.50 oz Mat                          32 sqft

   3.50 oz Cloth                     150 sqft

         6 oz Cloth                       90 sqft

       10 oz Cloth                       60 sqft

 13 oz Unidirectional           26 sqft

  1708 Biaxial                         27 sqft

  1700 Biaxial                        38 sqft

18 oz Woven Roving           40 sqft

1808 Biaxial                          27 sqft

50″ wide material = approx. 12 square foot per linear yard.

Example for figuring amount of fiberglass

needed.

Figure an overlap of 10%. This 5” for 50” wide fiberglass.  If the job is 100 Sq. Ft. Figure you will need enough cloth and resin for 110 Sq Ft.

COMMONLY USED TERMS

Pot Life – The amount of time from mixing the catalyst

into the resin until it begins to gel in the container.

Cure Time – The amount of time required for a

catalyzed resin to reach approximately 95% of its

ultimate strength.  Full cure may take up to 7 days, at

70°F, especially with Epoxies.

Post Cure – Additional heat applied after resin is gelled.

Done with heat lamps, tenting

To Fair – To fill and sand an irregular surface to make it

smooth and even.3

FRP – Fiber Reinforced Plastic. Can be Fiberglass,

Carbon or Kevlar with Polyester, Vinylester or Epoxy

Resin.

Fiberglass – A reinforcing material comprised of fine

glass fibers. Mat, Cloth, Woven Roving, Biaxial,

Uni-Directional.

Hardener (Catalyst for Polyester and Vinylester Resins)– MEKP for resins and BPO for putties and

compounds which when added to resin in the proper

proportions causes the resin to cure and turn from a

liquid to a solid. There is catalyst range for each resin.

Hardener( Epoxy) A curing agent that must be used in

the ratios specified.

Hand Lay-up The process of saturating layers of

fiberglass fabric with resin and rolling out air bubbles

and excess resin.

Thixotropic Powder – A powder (LBI-701 Cabosil) which, when added to  a liquid such as resin, creates a

non-sagging, non-running liquid with characteristics

similar to latex paint.

Microspheres (LBI-702 Glass Microspheres) These

tiny hollow glass spheres can be mixed with resin to

make a Fairing Putty.

Milled Glass Fiber (LBI-703) 1/32” glass fiber that

can be added to resin to provide structural strength to

putties containing Microspheres.