Category Archives: Techniques & Tips

Polyester Gelcoat Over Epoxy

by Jeff Wright — Vice President of Technical Services

Most production fiberglass boats are made with polyester resin, and we’re often asked if it’s appropriate to use polyester gelcoat over epoxy. WEST SYSTEM® epoxy is a wonderful material for repairing polyester fiberglass boats. One reason for this is the ability of epoxy to form a stronger mechanical bond to a damaged laminate than polyester resin. Epoxy also provides a better moisture barrier than polyester resin. Continue reading

There Will Be a Test

by Kay Harley

A research mentality and ongoing epoxy testing permeate all levels of Gougeon Brothers, Inc. We are committed to rigorous, long-term research on WEST SYSTEM products and their uses with other materials in wide-ranging applications. Studies include the basic chemistry involved, safety for users and the environment, formulation changes, product modifications such as adding pigments or UV additives, panel strength and stiffness with varying composite lay-ups, and the strengths of epoxy bonds, including hardware bonding. GBI commits capital investments to improve its testing capability and supports active ASTM involvement.

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Swift Solo

Swift Solo

Building for Long-Term Competitive Performance

by Bram Dally

Above: The Swift Solo in action. The complicated rig is designed to be managed by one person while they hang from the side of the boat.

Swift Solo, a single-handed skiff built by Bram Dally.

When Meade Gougeon asked me if I’d write a piece about what I’m up to for Epoxyworks, I was honored. He had read the January 2002 article on my single-handed skiff in Sailing World and offered the assistance of GBI (Gougeon Brothers, Inc.) to do some extensive testing for us on several composite samples. Continue reading

Epoxy’s Adhesion to Wood

Woods of the World Epoxy Adhesion Testing

by Tom Pawlak — GBI Technical Advisor

Above: Epoxy’s adhesion to wood is the focus of this study of dozens of wood varieties from Africa and the Philippines.

We recently purchased a 154-piece wood sampler from Eisenbrand Inc., Torrance, California. The 3″ × 6″ × ½” specimens originated from points all around the world. Each specimen was provided with its common name, scientific name, and country of origin. There were several specimens we’d never heard of in this study of epoxy’s adhesion to wood. Continue reading

Chopped Strand Mat

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

Epoxy Adhesion Over Stains

by Tom Pawlak — GBI Technical Advisor

Above: Testing of epoxy adhesion over stains was done with a number of different stains.

We have occasionally reported results of adhesion testing of WEST SYSTEM® epoxy to wood coated with various stains. In “Varnish Over Epoxy,” we touched on the topic of wood stains under epoxy and warned that some oil-based stains would cause an adhesion problem for WEST SYSTEM Epoxy. Since then, we have done some additional adhesion testing of epoxy over a number of stains. Continue reading

adding pigments to epoxy

Adding Pigments to Epoxy

by Bruce Niederer — GBI Technical Advisor

Above: Our study of adding pigments to epoxy.

We often get asked ‘What can I use to color my epoxy?’ The intended application is as varied as our customers. Often it’s simply to make it easier to paint over or to provide a color indicator between layers. Sometimes it’s to match a particular colored material in a repair. Maybe it’s for an art or craft project. The point is, people are often looking for a color other than the black 423 Graphite, 501 White or 503 Gray Pigments offered in the WEST SYSTEM® product line. What are some options for adding pigments to epoxy? And what are the pigment’s effects on the performance of the epoxy? Continue reading

A great tool when you want to prepare fiberglass laminates for epoxy adhesion

A Better Way to Prepare Fiberglass Laminates

by Tom Pawlak — GBI Technical Advisor

Above: The Rapid Strip Brush™ is a great tool when you want to prepare fiberglass laminates for epoxy adhesion.

During a recent inspirational hardware store visit, I discovered a rotary wire brush made by Norton™ called the Rapid Strip Brush™. It is used with an electric drill and produces results comparable to bead blasting or a needle scaler. The package says it can be used to abrade metal, masonry, and fiberglass. I immediately thought of a fiberglass application that I wanted to try it on. Continue reading

Screw strip out of particleboard furniture

Furniture Repair with G/5

A good method for particleboard furniture repair

by Tom Pawlak — GBI Technical Advisor

Above: Particleboard furniture repair can be tricky when screws strip out. G/5 Five Minute Epoxy Adhesive offers an easy solution to fixing inexpensive furniture when this happens.

I recently broke the leg off an old workshop table. The tabletop was made of particleboard covered with Formica®. The screws holding the leg in place had pulled out and taken chunks of particleboard with them. Continue reading

Testing Bolts Epoxy Bonded into Concrete

by Brian Knight—GBI Technical Advisor

Above: The final version of the test Brian devised to determine the holding power of bolts epoxy bonded into concrete. When the load cell registered 4000 lbs, he stopped the experiment.

The email exchange with Bob Warters in the article Installing a basketball goal is typical of the process we sometimes go through to answer a technical question. Most questions do not generate laboratory testing, but, in this case, the data we had available was limited. I was able to give Bob some shear strength data on concrete block from previous tests but was unable to find specific data on fasteners bonded with epoxy into poured concrete. I suspected poured concrete would hold a bolt better, but another data point would be reassuring. Continue reading