When it comes to kitchen countertops, selecting the right adhesive/sealant for each application is crucial to ensuring a durable, long-lasting, and aesthetically pleasing finish. Adhesives play a vital role in bonding materials where mechanical fasteners fall short. Each countertop application and substrate have unique properties, necessitating a range of adhesives to achieve the best results. By understanding the different adhesives and sealants available, fabricators and installers can make informed choices on which products to use, and when.
Undermount Sink Installation
For undermount sink installations, there are two primary options: a purely mechanical fastening system or a combined mechanical/adhesive fastening system.
Mechanical fasteners use a physical attachment to hold the sink in place. Examples of this type of attachment method include drilling into the underside of the countertop to insert bolts /clips or attaching clips and straps to the wooden cabinetry. Using this method increases installation time and also includes the risk of damage to the countertop.
Alternatively, using an adhesive like Component Bonder from Integra Adhesives allows undermount clips to be installed in advance, so that onsite the installer is able to fasten the clip bolts and fix the sink in place in just a few minutes. The position of the sink can then be easily adjusted, to make it easy to apply a silicone/MS Polymer to create a watertight seal before tightening into place. Look for an adhesive with high impact resistance, as sinks are subject to dynamic loads.
Substrate Mounting
Fixing the surface to the cabinet involves bonding two dissimilar materials: the countertop material (solid surface, engineered stone, natural stone, etc.) to wood (plywood/MDF). The differences in materials bear consideration due to different expansion and contraction rates, moisture absorption, flexion and impact resistance. In these situations, it is best to choose an adhesive with high elongation for flexibility. Fabricators typically consider three options:
- Hot melt glue: Hot melt is quick and easy to remove, making it ideal for templating, but it relies on a mechanical bond, which isn’t suitable for smooth surfaces
- Silicone: Silicone offers excellent properties for substrate mounting but is slow to cure with a typical fixture time of 24 hours.
- A specialized product (such as Substrate Bonder from Integra Adhesives). Substrate Bonder is a polyurethane adhesive developed specifically for this application. It cures in as little as 15 minutes and balances elongation, has high lap shear strength, and speed, making it ideal for this application.
Backsplash bonding and sealing
Traditionally, silicone is used for attaching and sealing a backplash, but unfortunately, it is slow to cure and lacks quick grab. An MS Polymer is a better alternative, offering quick grab and sealant properties in one. Available in a wide range of colors, MS Polymers provide a waterproof and color-matched seal, curing hard for easy cleaning and paintability. These durable products are also excellent for attaching shower panels and creating watertight seals in bathrooms.
Reinforced Rodding
Countertop rodding is a technique used reinforce natural stone. Rodding involves cutting a channel in the stone, inserting a stainless steel or fiberglass rod, and then encapsulating it. The material thickness, the cut outs and stone strength determine whether rodding is required. There are a few options for rodding adhesives on the market, but not all are created equal. Important characteristics to look for are low-shrinkage, thixotropic (self-setting), and quick curing for throughput. To explain further, solvent based adhesives can shrink during the curing process as liquid evaporates during curing. If the adhesive shrinks too much during cure, the channel can pinch in on itself, cracking the stone. It’s also good to use an adhesive that can flow enough to fill the relatively small channel, but also sets quickly, so as not to make a mess.
- Epoxy: Offers low shrinkage but has a very slow curing time, creating bottlenecks in fabrication processes.
- Hand-Mix Adhesives: Available options can be wasteful and messy. Incorrect activator-to-adhesive ratios can lead to quick curing, shrinkage, and brittleness, reducing the strength of the bond. Thin adhesive consistency is required for application, often resulting in leftover waste and increased fumes during curing.
- Rodding Bonder: A cartridge-based adhesive that cures in less than 15 minutes with virtually no shrinkage. It can be directly injected into channels, minimizing waste and enabling rapid completion.
Seaming, Mitering, and Laminating
Color-matched adhesives are essential for creating seamless countertops that appear to be carved from a single block. Each type of surface material, such as solid surface, engineered quartz, natural stone (granite, marble etc.), ceramic/porcelain/sintered, laminate and high pressure laminate, has its own requirements for adhesives. Fast-curing, high-strength MMA-based adhesives are ideal for solid surfaces due to their UV stability, moisture resistance, and low VOC content. For harder surfaces, like engineered or natural stone and ceramics, a zero-sag, penetrating adhesive is preferable, especially for on-site seaming with limited space. For external applications, UV-stable polyurethane adhesives outperform MMA or epoxy in maintaining color and durability. High-volume shops benefit from rapid-curing MMA-based adhesives to increase production efficiency.
Knowledge is power
To conclude, selecting the appropriate adhesive for each specific application in kitchen and bathroom installations is vital for achieving durable, high-quality results. Understanding the unique properties of various substrates and applications allows fabricators and installers to make informed choices, ensuring strong, long-lasting bonds and aesthetically pleasing finishes. From undermount sink installations to substrate mounting, backsplash bonding, reinforced rodding, and seamless countertop seaming, each task benefits from using the right adhesive.
Using adhesives over mechanical fixings helps avoid the risk of countertops cracking under dynamic loads, ensuring the longevity and stability of the installation. Additionally, the proper use of adhesives and sealants ensures watertight seals, crucial for preventing moisture damage and maintaining the integrity of kitchen and bathroom surfaces. By leveraging the knowledge and options available, professionals can enhance their craftsmanship, reduce installation time, and ultimately deliver superior results that meet the highest standards of quality and durability.
