A question we often find ourselves asking customers is “if we had a magic wand, what problem would you like us to solve?” Many OEMs in the transportation industry are facing similar issues. A issue that many manufacturers share is staining on vehicle sides; so, what causes it, and how can the problem be solved? In fact, most of this problem is caused by the products that are being used in certain applications. For instance, many manufacturers will use polyurethane adhesive to bond in the windows; then backfill the glass with the same product.
Causes of Staining
The key to this issue is UV Stability. UV light affects the chemical linkages in Polyurethane adhesives and causes the product to break down. There are several clear warning signs that an adhesive has been affected by UV light. The first evidence is discolouration, yellowing or chalking, which is then followed by cracks in the surface of the product. With Polyurethane adhesives, this degenerative process will begin within 1 to 2 years of the vehicle being in service. Once the adhesive starts to break down it means that water (i.e. rain) can penetrate the surface and can wash out the pigment contained within it. This pigment, which is typically black due to the application, will then run down the body sides causing staining. We already covered the importance of UV Stability in our technical insight 007.
How can you stop staining?
One answer, and the only true answer, is to change the product you are using for this application. Adhesives and sealants that use Formoa Polymer technology have much higher UV resistance than PU products, therefore have a much longer lifespan. They don’t degrade in the same way as polyurethanes therefore don’t cause staining on the body side of vehicles. Whilst PU adhesives have their place in certain applications, not all products were created equal! Use a polyurethane product for glass bonding and backfill and even your vehicle will cry black tears! Contact us to find out how we can help you solve problems.