Category Archives: Techniques & Tips

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 →

Protective Skin Creams

Do they interfere with adhesion?

Above: Protective skin creams. Photo by Nati Melnychuk on Unsplash

By Tom Pawlak — GBI Technical Advisor

We recently completed adhesion testing for a boatbuilder who was concerned about surfaces being contaminated by workers who use protective skin creams. The builder wanted to be sure that residue from the protective creams did not contaminate objects touched by workers throughout the day. We tested five products: Derma Shield™, Gloves in a Bottle™, Unique Skin™, SBS 46 Protective Cream™, and SBS 40 Medicated Skin Cream™. Continue reading →

Scrapers—Versatile Tools for Working with Epoxy

By Tom Pawlak — GBI Technical Advisor

Above: A putty knife scraper is being used as a push scraper.

My first experience with cabinet scrapers occurred shortly after hiring into Gougeon Brothers. Bill Slaby, a wood/epoxy technician who specialized in mold building, routinely used cabinet scrapers to remove irregularities on cured epoxy coatings. 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 →

Varnish Over Epoxy

By Tom Pawlak — GBI Technical Advisor

The appeal of well-maintained, varnished wood trim on boats is hard to deny. It evokes our past and we respect the owner because of all the time and effort it takes to apply and maintain the varnish. Continue reading →

Marine-Grade Plywood Basics

by Captain James R. Watson

Above: Marine-grade plywood basics include knowing how to select marine-grade plywood for flexibility vs. stiffness. This wing mast required plywood with some flexibility.

Since so many projects in Epoxyworks incorporate plywood, we felt it might be valuable to discuss briefly the types of marine-grade plywood and some construction methods best suited to it. It’s easy to understand why people like plywood and choose it for so many projects: it is readily available, comes in convenient sheets (typically 4’×8′), is pretty light for its stiffness and strength (1/8″ plywood weighs about 11 lb per 32 sq ft panel), and is a bargain when compared to the price of many composite panels. 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 →

Comparing Surface Prep Techniques

For Paints and Primers

by Joe Parker

Above: Surface prep testing using ASTM D3359. This calls for a single-edged razor blade to score a pattern through the coating. Applying a strip of masking tape diagonally across the pattern, then pulling it slowly back over itself will reveal the relative degree of adhesion to the substrate or primer.

Before you begin a project, it is a good idea to consider all of your options. Information about products or methods you may want to use is often available on product labels, from manufacturers, or your own experience. However, many times the information you need to make good choices is just not available. Then your best option is to test. In our most recent sailboat renovation, we had to figure out what to test for and how to do it. Continue reading →

Bonding to Corian™ and Wilsonart™ Laminates

By Tom Pawlak — GBI Technical Advisor

We recently did adhesion testing to Corian and Wilsonart surfaces with WEST SYSTEM 105 Resin and 206 Hardener at the request of a composite panel manufacturer. Corian and Wilsonart are mineral filled acrylic panels that look like granite and are often used as countertop material in kitchens and offices. Cabinetmakers and contractors typically use the panels in ½” thickness for residential applications. They are quite heavy, though not nearly as heavy as actual granite. Continue reading →

“If You Were Just More Flexible”

“…you’d see things my way!”

Are flexible epoxies better than stiff epoxies? How stiff is too stiff? How flexible is too flexible?

By Bruce Niederer — GBI Technical Advisor

Read the title of this article again. Could a statement be more confrontational? I sure didn’t think so when my ex-wife laid it on me! The issue of “flexible” vs. “stiff” epoxies seems to have become a battleground in a continuing debate among adhesive manufacturers, wooden boat builders, restorers and repair yards. Who’s right and who’s wrong? Is it even a “right or wrong” argument? Continue reading →