General considerations for epoxy bonded fasteners in wood
By Robert Monroe
With epoxy bonded fasteners, the idea is to balance the three parts, (fastener, epoxy and wood/hole) to obtain optimum performance. The key information needed is the tensile strength of the fastener, the shear strength of the epoxy and the withdrawal resistance of the wood or backing block. Continue reading →
A long time ago, I was building a 16 foot William F. Crosby design—a plywood, skiff-like sailboat. I was having trouble figuring out what to do because the plywood was only half as long as my boat was going to be. (Up to that point, all the boats I’d built were 8 footers.) I thought my prayers were answered when I heard that a distant lumber yard had some “special stuff” 16 feet long. But when I arrived at the yard, I thought I had been deceived. The “special” 16 foot plywood had been made that long by joining two standard 8 foot sheets, with a joint that looked pretty vulnerable and weak. I reluctantly bought the material on the assurance that it was plenty strong and I was not being deceived. Continue reading →
There are many ways to machine scarf bevels on plywood panels. The best method depends on how many scarf joints your project requires. If you need to scarf only two sheets of 3mm plywood, using a block plane and sanding block is a good low cost option. If you have a daily need to scarf many panels, a reliable machining method is a wise investment. This article reviews several popular scarffing methods and tools, to help you decide which is best for you. Continue reading →
This article about epoxy and oak was originally published in early 1995, and is shared at Epoxyworks.com for historical purposes. A dozen years after this article was written, we developed G/flex epoxies, which are rubber toughened to withstand shock, vibration, expansion and contraction. G/flex epoxies adhere tenaciously to many difficult to bond substrates, including dense and oily wood species like oak. Continue reading →
Before beginning a project, it’s a good idea to test the adhesion between epoxy and the materials to be used. Preliminary adhesion tests can help you choose the best materials and surface preparation methods. It can also help to avoid a surprise bonding failure.
At Gougeon Brothers, Inc. we use a Pneumatic Adhesion Tensile Testing Instrument (PATTI) for adhesion tests. After the PATTI test stud is bonded to the test surface, the stud is pulled in tension until it releases. The instrument gauge gives a precise pounds per square inch reading at failure. Continue reading →
Editor’s note: This article was originally written in 1994, long before we developed G/flex epoxies which offer vastly superior performance in bonding to plastics including PVC. A much more current article on this subject is Gluing Plastic with G/flex Epoxy by Tom Pawlak and Jeff Wright. If you’re interested in gluing PVC with epoxy, we suggest you start there. The following article is published at Epoxyworks.com for historical purposes only.
Our 403 Microfibers and 405 Filleting Blend are excellent structural fillers but they’re fibrous and leave a rough surface when used to make fillets. To end up with a surface that is ready for coating or re-bonding without having to remove amine blush or sand smooth, apply a narrow strip of 879 Release Fabric after the fillet is made. Continue reading →
Strategies for successful application and curing of epoxy at low temperatures
Epoxy behaves differently in cold temperatures. These handling tips can guide you in obtaining optimum performance from epoxy in this fall and winter.
Epoxies reach a higher percentage of their potential physical properties when mixed and applied at temperatures above 60°F. However, you can use epoxy at lower temperatures and still obtain a dependable bond. The key is adapting your handling and application techniques to cold temperatures. Whether you live in a Northern or Southern climate, it is helpful to know how temperature affects epoxy chemistry, how epoxy handles differently in cold conditions, and what steps you can take to assure dependable bonds in cold weather. Continue reading →