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.
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.
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?
Longtime readers of this column may note that I have always been a fan of silicone sealants; however, I worked for a manufacturer of these materials for many years, so I hope I can be totally objective. I have no doubt that the durability and longevity of silicones cannot be exceeded in most applications. However, I can offer you several observations from my personal experience using them at home.
Adhesives are often a better way to assemble plastics than by using mechanical assembly with fasteners. For example, fiberglass composites are routinely bonded with epoxy or reactive acrylic adhesives in the automotive and marine industries because they give high strength and durable bonds.