Perseverance is the key to selling adhesives products successfully.

by Richard Vurva

Remember when you were a kid and you wanted to glue something together? All you needed was a trusty bottle of Elmer’s glue.

Those were much simpler times. Today, end-users have many more options when it comes to selecting the right adhesive product to bond two surfaces together. Choices include acrylics, anaerobics, cyanoacrylates and epoxies.

Dave Bongiorni, marketing development manager for adhesives manufacturer ITW Devcon, says salespeople need to be unrelenting in questioning end-users about how they intend to use the adhesive.

For example, it’s not enough to know the type of material to be bonded. Salespeople must ask follow-up questions to determine if the material will be placed under loads, temperature extremes or other environmental factors.

Suppose a customer is trying to bond two pieces of metal together. At first blush, an epoxy adhesive seems to be the best solution. But if the end-user neglects to mention that the metal pieces, once bonded, are bent to a 45 degree angle, the epoxy may be too brittle. An acrylic adhesive might be a better choice.

“The way I look at it, you have one chance to make the right recommendation. So you need to get it right,” Bongiorni says.

Selling adhesive products today requires salespeople to have a basic knowledge of not only the types of adhesives available, but also terms such as shear strength.

“With MRO especially, you want to know if the bond needs to be repairable,” says Matt Donelin of Loctite. “Will it be a permanent fix or will someone have to come back in a few months and change it?”

One way to measure the sticking power of an adhesive is by measuring its shear strength. What’s shear strength?

Think of two microscope slides like the kind you used in a high school biology class. Suppose you put a drop of glue on one slide, about a half-inch from the end, then placed another slide on top of it and pushed it down. Let that cure. Now grab the ends and try to slide them apart.

“That’s putting shear on the joint,” says Donelin. “The glue is trying to hold two surfaces together that are trying to slide.”

Six common adhesives
Structural or load-bearing adhesives add strength to the products they bond together. They’re used to build products as varied as office furniture, boats and automobiles.

Here’s a brief description of six common adhesives.

Anaerobic adhesives are one of the most easily applied structural adhesives. Because curing is triggered by oxygen deprivation (hence the name “anaerobic,” or “without air”), they will not cure prematurely. They range from thin liquids to thick pastes. Although they have high cohesive strength, they have low adhesive strength and are not suited to permeable materials. Anaerobics are generally used as thread fasteners.

Cyanoacrylate adhesives are easily applied and offer extremely fast cure rates. Some will cure to a strong joint in 2 to 3 seconds. They bond plastics and rubbers to themselves or to other substrates. However, they exhibit poor impact-resistance, are vulnerable to moisture and solvents and are suitable only for bonding small areas.

Epoxy adhesives are the most widely used structural adhesives. Two-part resin/hardener systems will solidify on mixing (sometimes accelerated by heat), while one-part materials require heat to initiate the reaction of a latent catalyst. Epoxies offer very high shear strengths and can be modified to meet a wide variety of bonding needs.

Hot melt adhesives form flexible and rigid bonds, achieve 80 percent of their bond strength within seconds, bond permeable and impermeable materials and usually require no elaborate surface preparation. Hot melts are insensitive to moisture and many solvents, but soften at high temperatures.

Methacrylate adhesives provide a unique balance of high tensile, shear and peel strengths with the maximum resistance to shock, stress and impact across a wide temperature range. They can generally be used without surface preparation when joining plastics or metals.

Polyurethane adhesives are usually two-component products. They are known for toughness and flexibility even at low temperatures. They have fairly good shear strength and excellent water and humidity resistance, although uncured urethanes are sensitive to moisture and temperature.

Silicone adhesives are known to have good gap filling capabilities. They are good for bonding glass to most other substrates, flexible and have good water resistance. Their flexibility and low strength make them less desirable for bonding structural loads.

This article originally appeared in the November/December '99 issue of Progressive Distributor. Copyright 1999.

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