Category Archives: Epoxy Products

Effects of Surface Treatment

On Epoxy Adhesion to Metals

by Brian Knight—GBI Technical Advisor

Above: Surface treatment can make all the difference in epoxy adhesion to metal. Photo by Manny Becerra on Unsplash

We have performed tens of thousands of adhesion tests over the years and many of these tests were done on metal surfaces. Below is a summary of tests done on a variety of metal surfaces and done with a variety of surface preparations. As you look at the chart, notice the surface preparation that gives the highest number.

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WEST SYSTEM Epoxy vs. Polyester

for Fiberglass Boat Repair

by Tom Pawlak — GBI Technical Advisor

Above: Epoxy vs. polyester in a typical fiberglass boat repair cross-section.

Even though we’ve been promoting the use of WEST SYSTEM® Epoxy for repairing fiberglass boats (boats made with polyester resin) in our manuals and Epoxyworks for many years, we continue to receive inquiries asking whether it is appropriate to use epoxy for polyester boat repair. Because of the misinformation still prevalent in marinas, local yacht clubs and on the Internet, we felt it was time to restate the case for epoxy. Continue reading →

Chopped Strand Mat and Epoxy

by Tom Pawlak — GBI Technical Advisor

Above: Wet-out chopped strand mat and woven fabric test samples are prepared for moisture uptake testing.

Chopped strand mat, in fabric form, is sold on the roll and in small folded packages. It is made up of 1″-2″ long fiberglass strands that are randomly oriented and typically held together with a styrene-soluble binder that acts like glue connecting the fibers. The binder is designed to dissolve upon contact with styrene in polyester resin or vinylester resin. Once dissolved, the fabric softens, allowing it to drape around curved shapes. It comes in a variety of weights between .75 oz to 3 oz per square foot. The most popular weights are .75 oz and 1.5 oz. Continue reading →

G/5 Adhesive Tips

Working with G/5 Resin & Hardener

By Tom Pawlak — GBI Technical Advisor

Above: To simplify mixing G/5 Resin and Hardener for a large project, Grant made a carrying pallet with sixteen holes, sized to hold 1-ounce mixing cups (pill cups purchased at a food service outlet). The pallet was covered with duct tape so glue drips could be peeled away. Note that a mini cupcake pan could be dedicated to this kind of task as well.

Many of us at Gougeon Brothers experiment with WEST SYSTEM® products on personal projects at home as well as at work. We often push products and techniques beyond the limits recommended in our literature. Sometimes the experiment fails, sometimes we discover something very useful. Continue reading →

Testing Large Bonded-In Fasteners

by Brian Knight—GBI Technical Advisor

Above: Scheherazade, the 154’7″ yacht that required testing of large bonded-in fasteners.

Cover Photo: The 154’7″ Bruce King-designed Scheherazade resting on her massive keel at Hodgdon Yachts in East Boothbay, Maine.

Scheherazade is a 154′ 7″ Bruce King-designed ketch under construction at Hodgdon Yachts, in East Boothbay, Maine. Scheherazade is 60% larger than Antonisa, the last Bruce King/Hodgdon Yacht collaboration, and is the largest sailboat under construction in the United States. Continue reading →

Estimating Epoxy Amounts

By Bruce Niederer — GBI Technical Advisor

Above: The layout of an Optimist pram provides an example of how to go about estimating epoxy amounts.

This formula will help you estimate the amount of mixed epoxy needed to wet out fiberglass cloth (assuming a resin-to-fiber ratio of 50:50) and apply three rolled epoxy coats to fill the weave of the cloth, i.e. “fill coats.” Continue reading →

Product Highlight: 804 Reusable Mixing Sticks

Reusable Mixing Sticks are practical mixing, application, filleting, and cleaning tools that have found many places in our workshop and toolboxes, and we believe they will be in yours, too. The squared, beveled end reaches into the square corners of the 805 and 806 Mixing Pots for thorough mixing of epoxy and blending of fillers. Continue reading →

Thinning WEST SYSTEM Epoxy

by Brian Knight—GBI Technical Advisor

A question frequently posed to our technical staff is “can I thin WEST SYSTEM® epoxy so it will flow or penetrate better?” The answer to that question is “yes, but not without consequences.” Many of the advantages of thinning epoxy are offset by disadvantages in other areas of epoxy performance.

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Adding Pigment to WEST SYSTEM Epoxy

by Brian Knight—GBI Technical Advisor

Adding a coloring agent to WEST SYSTEM® Epoxy is frequently done to make colored castings, highlight an epoxy coated surface, act as a colored base coat for paint, etc. Most powdered pigments are satisfactory, as are acrylic paste pigments and universal tinting pigment. Continue reading →

Getting the Most out of Mini Pumps

by Jim Derck—GBI Technical Advisor

When using WEST SYSTEM® 300 Mini Pumps, the most important things to remember are:

Read the instructions.
Use one full pumps stroke of resin for each one full pump stroke of hardener to get the proper resin-to-hardener ratio.

If you’re ever concerned that your pumps aren’t metering properly, simply mix a test batch of 3 pump strokes each of resin and hardener. Stir thoroughly and make sure it’s fully cured before continuing with your project. Continue reading →