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This is a very interesting question. Many adhesives are used in what is called a “zero gap” situation, where the adhesive is applied between two closely fitting surfaces, which are then clamped together.

The primary forces are shrinkage of the adhesive on curing and large differences in thermal expansion coefficients between the substrates and the adhesive. High stresses can cause delamination of bonds or damage to the substrates, such as glass cracking.

Dave Dunn's December 2017 column.

It sounds like you sell to several different markets. Although there is some overlap of silicone or polyurethane markets, they are often used in distinct applications.

We’ve been trying to get the metal button of a rear-view mirror to bond to a new windshield. We’re in the summer heat of Las Vegas where it is routinely over 110°F―and even hotter inside a closed car. We’ve tried all the typical glues but, while the button will cure and hold, it falls off when the mirror is attached.

We use an acrylic UV adhesive to bond and coat a complex medical device, and get areas where there is incomplete curing. How can we improve this?

Solvent-based contact cements, such as those based on chloroprene rubber, were traditionally used for this application. They work very well and are available in spray or aerosol versions. However, many users are now reluctant to use them because of emissions regulations, safety concerns or disposal issues.

Can you help us to get rid of the mess created from using fumed silica in our silicone and polyurethane adhesive manufacture? It is so lightweight that it covers the entire factory.

We have a customer who wants to use an adhesive-backed expanded PTFE gasket strip on a steel substrate. However, the customer wants to be able to remove and reapply the strip without losing adhesion. We do not make ePTFE gasket strips, but we have imported some samples for the customer to test. They are not satisfied with the results. I must admit, I am not surprised. Is there such a thing as a PSA that can be removed and reapplied a number of times without losing adhesion?

Polyurethanes can be one- or two-component systems. The single-component systems comprise a polyester or polyether polyol that has been end-capped with an isocyanate.