Offset edge buildup strips (not flush) creates a place to trap stress and can lead to cracking.
Editorís Note: This is the first of three articles on solid surface failures; the other two articles (covering cracks in inside corners and cooktop cutouts) will be featured in future issues of Surface Fabrication magazine.
As human beings we are able to handle a lot of stress. As we get older it seems that our ability to handle more stress or pressure increases. People even take classes or training on how to cope and deal with stress and pressure. But it is proven that everybody has a breaking point. If you put enough stress on someone, they will eventually break. The same can be said for solid surface countertops.
As we all know, stress is the leading cause for breaking a countertop or having the dreaded call from that customer who says, ďI have a crack in my counter.Ē
Like the classes that we can take to better understand and handle pressure, we, too, as fabricators can get a better understanding on how to deal with stress while fabricating a countertop or something made from solid surface material. In life, we know that eliminating all the stress is impossible, so the goal is really to manage it.
The front edge buildup crack rarely ever happens at the shop when you can fix it easily; no, it almost always happens when you are at the customerís house right in front of the customer. While bringing in that large section of counter and trying to get it flat on the cabinets, you hear the dreaded snap sound as a crack comes off the front edge and into the deck. Hopefully all the cussing and swearing has stayed in your head as you try to get the countertop back into the truck without further damage, all the while explaining to the customer that everything will be perfect when you return.
Of course, there are also instances where the countertop cracks long after installation. I have often seen cracks that start at the front edge; but were triggered by exposure to excessive heat, such as when homeowners have used an electric frying pan or similar appliance without protecting the countertop with a trivet. Expansion and contraction on areas of countertops occur because of heating and cooling cycles and are a major contribution to stress failures of installed countertops. So, it is of the utmost importance that consumers are made aware of the need to use trivets in these situations to avoid damaging their tops. Of course, what you tell the homeowner to do and what they actually do once youíve left arenít necessarily the same thing.
So, consumer-caused failures aside, what causes the sickening sound we all hate to hear when transporting or installing a top? The invisible counter-killer called stress is the culprit. Understanding a few basic principles of stress as related to our countertops will help reduce the risk of failure.
Stress is about compression and expansion. The stress that broke the front edge came from the material not being able to expand or stretch any further. As the counter is being flipped to a flat position and not being supported, it sags. It is the bow that is producing the stress. You are asking the front edge buildup and the rest of the top to do two different things at the same time.
As the sag or bow in the counter gets greater, the stress builds, until it finds a weak spot to relieve itself. Here is what you are asking the counter to do: At the greatest point of the bow or sag, you are asking the material at the top edge of the counter to compress itself, while at the bottom edge of the buildup you are asking the counter to stretch or become longer than it is. Technically speaking, you are compressing molecules together at the top and stretching them apart at the bottom. It is the bottom edge of the buildup that is experiencing the greatest stress.