By Cameron DeMille
Easy Stone Care recently held a training class at our facility, and one of the questions that comes up all the time is, “What do you use to fill chips in countertops?”
The answer is always the same: “It depends.”
When deciding what type of glue to use when filling chips or doing repairs, the first question that should be answered is, “What is appropriate?”
Not all glues are created equally and some cannot, or should not, be used in certain situations. In this article, we’ll address urethane, which is at the top of the food chain. Urethane is the Mac Daddy of all glues when it comes to durability. UV stable, moisture stable, strong bond and very hard (usually), It can be clear, semi-opaque, solid-colored OR tinted with an appropriate color kit.
Some urethanes cure fully rigid and hard, like an epoxy, but they can also be formulated to cure semi rigid, to allow for expansion and contraction with movement in fault zones, or for freeze-thaw conditions. This can be a huge advantage in certain applications where a more-stable material needs to be used for longevity without sacrificing flexibility.
One huge advantage of urethanes is they typically do not contain solvent(s) like other resins and epoxies, so the chances of bleeding into the stone are slim to none. When working with materials that are at a high risk of absorbing glue into laminations, miters and seams, choosing a quality urethane adhesive is one way to avoid this. Urethanes will not shrink when curing like other adhesives, but they can expand.
The downside of urethanes is that they can be temperature and moisture sensitive during curing. This means that in a hotter climate, like we have here in Palm Springs, the glue will cure much faster during the summer. During exterior work, the cans are kept in a cooler with ice, or in a refrigerator, to keep the glue temperature down. This will retard the curing time and allow more working time to get the repair in place without it gumming up on you.
In coastal climates, the humidity is much higher and can cause the glue to expand when curing. For restoration guys, this is not such a bad thing, but when gluing two pieces together, you want to have those pieces clamped tight. Once you get past the short learning curve, these glues can be a major asset to your arsenal.
This time, we’ll focus on a line of urethanes produced by Bonstone Materials Corp. They make several variations, with the newest being their recently introduced color of Glacier, under their Touchstone line. Glacier was introduced several years ago in clear and transparent white and quickly became a big hit, especially with the guys working with a lot of Carrara and similar marbles.
Carrara, Calacutta, Bianco Venetino and similar marbles have always been notoriously difficult to repair and hide seams on, due to their transparent nature. Glacier White is a perfect match right out of the tube/can.
In addition to the Glacier lineup, which is currently available in five colors: Clear (Flowing or Gel/Knife Grade), Transparent White, Solid White, Cream and Gray. Bonstone also has the Last Patch™ line of LP Gel, LP Dymond and LP Limestone.
• Last Patch Gel is semi-opaque and cures semi-rigid. This allows to be used in areas where movement is expected, such as freeze-thaw conditions and to account for movement here on the San Andreas Fault Line. (Our offices at Easy Stone Care are about three miles away.)
• Last Patch Dymond is similar to Gel, but it cures rigid, which allows it to be sanded smooth and polished.
• Last Patch Limestone is in a league of its own, with Part A consisting of a gritty, sand-like material that allows it to mimic the texture and finish of real limestone.
And, the Touchstone Liquid Tint kit can be used to dial in whatever color you need
