Solid Surface Solutions Can Prevent Stress Risers
By Russ Lee
It was also well supported on all four edges on firm and level cabinets. Yet, the very next day, it cracked split right through the middle. The homeowner had laid a couple of heavy books on the top, and it popped.
Upon close examination of the countertop I found that, in the course of fabrication, I had pieced and glued together strips of material for the front edge, and had left a void in one of the joints. This half-inch sliver was barely wide enough to slide in a piece of paper, yet it acted as a focal point for all of the stresses present in the countertop to congregate. So, when a minor outside force was applied to the top (in this case, a couple of heavy books), it was literally the straw that broke the countertop's back. I had created what we refer to in the industry as a "stress riser."
The weak link
Lenny Elbon, a research chemist for Fountainhead, explains that solid surface, although made from polymer resins, is often labeled as a ceramic-type material. "Other ceramic materials include glass and natural stone," he says. "These materials are very strong, don't stretch much under a load, and when they reach their yield point, suffer catastrophic failure.
"A good example of the effect of stress risers is demonstrated with glass, which has a very high strength, provided the sample is smooth and defect-free. But, if the surface of the glass is scratched, the strength is greatly reduced. That's why glass cutters always score a glass pane before breaking it. The same thing happens to solid surface," Elbon continues.
That's not to say that introducing a scratch on the surface of a finished countertop installation will cause any damage other than a cosmetic blemish. But, it does explain why a fabricator may appear almost fanatical in his quest to identify and eliminate stress risers in his countertop installations.
This is why fabricators are careful to sand smooth any chips or cracks that may have occurred during fabrication, and are adamant about easing all inside corners with a minimum half-inch radius. This is also why fabricators make their cut-outs with a smooth-cutting, yet dust-churning router instead of a relatively clean jigsaw, which can leave microscopic cracks, or stress risers, in the solid surface. In fact, just about anything that leaves a sharp corner in solid surface has the potential to create a stress riser.
You probably know that solid surface absorbs heat and cold readily and will grow or shrink in direct proportion to its temperature. I'm reminded of a fabricator in New England who once glued a front edge on a solid surface top in 7Þ weather as a test, and found that the entire top had grown 3/8" when he brought it back up to a normal temperature the next day. With the countertop in constant motion as it reacts to its environment, the forces of stress circulate throughout the material looking for weaknesses, and are drawn to any defects.
The right method
You may have heard your fabricator mutter under his breath when a certain brand of drop-in range
is specified for the kitchen. This is often because the design of the appliance leaves insufficient room under the decorative flange to build in a proper radius at each of the four inside corners of the cut-out.
Your fabricator knows that under such circumstances, it's difficult to build in the needed stress relief for the forces that will be caused as the range heats up and cools down. Thus, he is looking at a potential crack at some point in the future, and he is powerless to avoid it.
The solid surface industry has put a lot of time and effort into engineering fabrication methods for range cut-outs that virtually eliminate cracks due to unequal stress forces. These methods include detailed instructions on the shape of the cut at the inside corner, as well as the type of reflective tape and other heat shielding materials to use and how to apply them.
Most of these methods require more than 1/4" of space between the cooktop box and the outside of the decorative flange to be effective. Hence, it's a good idea to consult your fabricator about the range of fabrication options available when you consider specifying a cooktop that is non-solid surface friendly. The solution may include the use of a decorative steel or tile flange around the perimeter of the cut-out, or even a layered solid surface ledge. Anything that allows the fabricator to build in a generous radius would be appropriate.
The message here is clear: If you confront and address a potential problem at the beginning of a project and incorporate the solution into the final design, your client will be much happier than if you wait until a problem develops and adopt a band-aid approach.
The same principle applies to the fabrication of any other inside corner, such as wrapping solid surface around architectural moldings and cabinetry, or hard seaming backsplashes to the countertop deck. If you build a radius into your preliminary designs, the finished product will have the look and feel of a custom installation, and it will last indefinitely.
Russ Lee is editor of SolidSurface
magazine, a bi-monthly sister magazine of Kitchen & Bath Design News that is aimed primarily at solid surface fabricators. Lee, a former fabricator himself, is a regular contributor to K&BDN, focusing on ways that the kitchen/bath designer and specifier can forge a more effective and profitable working relationship with the solid surface fabricator.