Category Archives: Materials Testing

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 →

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 →

Gluing Plastic Dimensional Lumber

by Patrick Ropp—GBI Technical Advisor

More people are using recycled plastic/wood composite lumber for decks and other various projects. Although each manufacturer of recycled plastic lumber has his own blend, we found that most are using very similar ingredients: an equal amount of melted recycled plastic mixed with recycled wood chips or sawdust and then extruded in the form of dimensional lumber. Since the wood is encased in plastic, the plastic/wood composite boards are supposed to last longer than traditional decking materials and carry a good warranty. Many of these boards are not intended for use as structural members, but they Continue reading →

Testing House Paint Primers

By Tom Pawlak — GBI Technical Advisor

Gougeon Brothers, Inc. regularly engages in testing to support those who use our epoxy in architectural applications, both in new construction and repairs. In the past, we have tested the compatibility of house paint primers over WEST SYSTEM® epoxy and found that a variety of primers worked well. Latex primers especially performed well when applied over cured epoxy, even when the epoxy was marginally prepared prior to painting (Epoxyworks 7, Spring 1996). Continue reading →

Mold Release, PVA and Hairspray

By Tom Pawlak — GBI Technical Advisor

PVA (polyvinyl alcohol) is a water-based liquid plastic that can be applied to waxed molds to prevent molded parts from sticking. PVA is not always required. Often laminators rely solely on mold release wax to create a surface contaminant on the mold that allows parts to be removed. However, on complicated molds and on new molds, when the risk of sticking a part in a mold is greatest, PVA can be applied over a waxed mold to minimize the chance of sticking a part. 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.

Continue reading →

Science Fair Testing Wins Awards

By Bill Bertelsen

We like to think that all our customers are considerably above average, but every once in a while we encounter someone really exceptional. On January 25, 1999, our tech service department took a phone call from Elizabeth Tedford, a 7th-grader from Lansing, North Carolina. She was working on a science fair project that involved testing the adhesive strength of epoxy. Continue reading →

Hydromat Panel Test, an ASTM Standard

by Bill Bertelsen, GBI Test Engineer

A stack of Bram Dally’s 12″x12″ composite panels are ready for phase one testing as Bill Bertelsen adjusts the hydromat fixture.

Previous Epoxyworks have reported test results from the “Hydromat,” a unique structural test developed at Gougeon Brothers, Inc. The American Society for Testing and Materials (ASTM), after a rigorous review by its D30 Committee on Composites, approved the Hydromat test method as an official ASTM standard. Continue reading →