Adhesives: Sticky Situations

   No amount of caulk or epoxy will keep poorly set countertops in place over the long term. My approach to adhesives is to look at them as agents that bond a quality setting job in place for good.
   I want to be able to go back in 20 years and see the countertops I installed still sitting pretty – seams intact, sink secure, and backsplash still bonded tight. In order to do this, the quality of the set before I apply the first glue needs to be self-sufficient.
   My number one rule of thumb is that if the pieces won’t sit solid without the adhesive, I don’t consider them ready to glue. This includes base pieces, sinks, and snack bars. Relying on adhesives to keep your pieces where you want them to be seems to me to a real risk.
   By getting your countertops in their finished locations without adhesives, you make sure that when the glue and epoxy are applied, there won’t be any pressure on the bond they create. A bond without external pressure trying to pull it apart is a quality bond that lasts a long time.
   Once you dry-set your countertops to perfection, your adhesive choices are many. I base my choices on performance, cost, availability and – I’ll admit – a few of my own personal preferences.
   When judging the necessary performance issues of an adhesive to glue pieces in place, I try to consider what kind of use the surfaces will get. I also try to envision what the worst-case scenario for movement could be if the adhesive somehow ends up being the only thing holding those pieces in place.
   With this in mind, raised snack bars are at the top of my concern list. I’ve replaced a couple that fell off after being improperly installed by others, and I can assure you falling stone does some real damage.
   For granite and engineered-stone snack bars, I like to use a standard construction adhesive. There are many brands, but the main thing is that the adhesive does NOT maintain flexibility after curing. Not every tube will tell you if this is the case, so you may need to squeeze out a few samples lines of the product and let it set up overnight.
   In the end, the adhesive should be rock-solid and bonded tight to the top of the snack-bar wall and bottom of the stone. Make sure the stone and the wall are clean before application. If the top of the snack-bar wall has primer, paint, or drywall mud on it, I belt-sand it off before applying adhesive.
   Be generous when using this stuff. I like to run a back-and-forth bead across the entire top of the snack-bar wall, and then fill in any voids that appear after the final leveling and overhang adjustments. The more it bonds across the entire surface, the less likely it is that any one spot will undergo undue pressure with use or misuse.
   Tape off any surfaces you want to stay clean prior to using construction adhesive, including the visible faces on decorative wooden support brackets. The adhesive is tough to remove from wood because it smears around and darkens.
   Clean off any squeeze-out right away. If you let it begin to set and then try to clean it off it globs up and sticks to everything and makes a real mess.
   When you’re setting down a snack bar on top of the adhesive, try to set it precisely where it needs to be. Sliding a counter around on top of the adhesive spreads it out and reduces the amount available to bond. It’s also a nasty bit of work to clean off the bottom of the snack bar piece.
   You should also baby-sit the piece for a while to make sure the counter is not sliding or tipping in an unexpected way. While the construction-adhesive bond is very strong after curing, the piece can get a little slippery before the adhesive sets and move off the intended spot.
   Be especially mindful when the curing process begins and the adhesive gets tacky, because it starts to have memory. Bumping the piece to make small adjustments becomes impossible as the adhesive returns the piece to where you started.
   While the other contractors might think it’s funny to watch a grown man argue with glue, it won’t give them confidence that you know what you’re doing. Make sure the piece is in the right spot when the glue starts to dry and you’ll avoid the embarrassment.
   When setting countertop base pieces, I use construction adhesive for the back and side rails of the cabinets, and also to fill in any voids between the top of the cabinets and the bottom of the stone caused by shimming. Whenever possible, I also glue my shims into place, so there’s no chance they can fall out into the cabinet.
   I use construction adhesive on my standard and full-height back splashes as well, and dry-fit before gluing. A full-height back splash glued in place a little out of vertical can wreak havoc on the seam joining it to the next piece.
   Once the splash pieces are set, I tape off where they meet the base pieces and seal them with silicone or, in the case of many engineered stones, a color-matched caulk provided by the material manufacturer. I apply a bead and then work it into place with my fingertip.
   After this, I pull the tape off, taking care not to let it slide across the finished countertop. I then wet my finger and smooth down the caulk bead.
   I use color-matched or clear silicone caulk on the front rail of the cabinet, because it looks better than construction adhesive as a finished product. I also tape off the wood on the front rail to avoid a silicone mess on the cabinetry.
   If you do happen to get silicone on the wood, clean it as thoroughly as possible with dry paper towels and then hit it with a little denatured alcohol. Avoid acetone or paint thinner, as it will take off most cabinet finishes.
   When mounting sinks, I use the same rule of thumb about dry-fitting. Whether I’m using clips or mounting the sink on top of boards inside the cabinet, it has to fit tight against the bottom of the stone before the glue goes on.
   To mount sinks in granite and engineered stone, I always use 100-percent silicone. Again, there are many different silicone manufacturers, so feel free to experiment with different ones.
   Make sure that, when you position an undermount sink, you cover the entire rim with a bead of caulk. This serves two real and useful purposes.
   First, it seals the entire sink to the bottom of the stone, and ensures water will never drip down into the base cabinet. I would caution against missing a spot, as twice I’ve had plumbers fill the entire sink up with water, right to the top of the stone, to check the seal. Both times I passed the test, but I wasn’t comfortable watching.
   Second, by having a bonded bead the entire way around the top of the sink, there is no weak spot at which the adhesive can begin to fail and then travel. A sink that has been thoroughly bonded with silicone is in place for good – just try taking one out. I stood inside a dented stainless steel sink held in place by only a bead of silicone and it didn’t budge. I’ve never worried about a sink falling out since.
   As with construction adhesive, silicone is a real bear to clean up if you make a mess. When you dry-fit your sink, use tape to mark the spot where the stone is in place. You now have a guide for pulling the sink into exactly the right position when there’s a silicone bead on it.
   Sliding a sink around to get it in the right place reduces the amount of silicone available to bond and makes a mess on the top edge and sides of the sink. Cleaning out a sink full of silicone drips is a time-wasting venture.
   A good sink bond will create some silicone squeeze-out as you tighten the clips or insert shims on your wooden sink frame. Clean this up right away with your finger and lots of clean paper towels, and then remove the silicone haze with a light acetone washing.
   Sinks are worthy of a little babysitting until you are sure they aren’t going to move around. The silicone may continue to squeeze out for a little while, so hovering over a sink for a couple minutes allows you to keep cleaning the edges.
   Construction adhesive and silicone are pretty common items, so finding a source for them is easy. Finding the best deal may require a little shopping around. For color-matched and specialty caulk, try a favorite stone-products vendor.
   If you need a caulk that you can’t get at the local hardware store, always make sure you’ve got plenty of it along. Running out of a caulk color halfway through a job is a real pain, especially if you’ve traveled any distance for the installation.
   For your everyday caulk and adhesive, find a local source that will give you a deal if you buy in bulk. Also, buy and use caulk stoppers so that your half empty tubes stay fresh and don’t go to waste.
   Last, but not least, buy your installers good caulk guns with easy triggers and quick shut offs. These will prevent messes and carpal-tunnel syndrome
   
EPOXIES
   I don’t joke around too much with clients, but if they ask me what I use to glue the seams together I’ll sometimes tell them: “Elmer’s.”
   I’m joking here, of course, but I’m also making a point. One of the main reasons why I spend so much time and effort setting the tops is that I then won’t need much to keep the pieces tightly together.
   For most of my granite and engineered-stone seams I use a knife-grade polyester epoxy, either white or transparent, along with colorant. Once again, there are many different manufacturers and I suggest trying each of them out until you find a favorite. They all work well to bond pieces together, so the differences in use for me are related more to subtle qualities.
   On a daily basis I use Akemi or Wood and Stone transparent knife grade for the middle section of the seam. Both are easy to color, and both react well when you add a relatively small amount of hardener to create a less-brittle, slower (and, in my opinion, stronger) cure for your seam. But, after the seam is set and cleaned up, I use K Bond transparent knife grade for the top two coats because I like the way I can carefully shave off excess epoxy without having it chip or discolor too badly.
   While I’m sure none of the manufacturers would recommend mixing their products together, it works for me. I haven’t had a broken seam yet.
   Epoxy performance issues, in my opinion, are largely related to the skill and experience of the installer using them. If you add too much hardener, making the epoxy literally too “hot,” your final product will be a brittle and poorly bonded seam that will likely break in its lifetime. Adding way too much colorant seems to water down and weaken the epoxy as well.
   Follow the manufacturer’s recommendations pretty closely when it comes to color and hardener. You’ll be able to vary according to your own needs after a little experience.
   Another performance failure I’ve seen is when the installer doesn’t coat the entire edge of the seam with epoxy. The best bond is achieved by entirely “buttering’” both edges of the stones to be seamed. You’re kidding yourself if you spread a little epoxy on the top and think it’s not going to crack.
   Once the stone edges are buttered, I highly recommend using a seam puller in order to achieve a tight, uniform seam. I pull my seams very tight, hopefully to the point where they are hardly visible.
   Epoxy should squeeze out the entire length of the top, bottom and front. I scrape off the excess and check to make sure the seam’s level, making any necessary adjustments.
   Once again, I baby-sit the work to make sure nothing moves until the epoxy sets. On larger jobs, it’s very handy to have a couple of seam pullers and more than one person on the crew who knows how to use one.
   Once the seam cures, I remove the puller and razor off the rest of the epoxy. Since polyester shrinks slightly, I apply a couple more top coats of epoxy on the seam itself. These are mixed with more hardener for a quicker cure, but not one so fast that the epoxy gets brittle.
   Warped granite is another matter. If the slab needs some serious pushing to make a decent seam, I go right to Bonstone two-part structural epoxies. My cure time may dramatically increase, but the strength I gain in the seam is well worth it.
   While getting a seam to set takes a little practice, coloring it right takes an artistic eye and lots of patience. The main thing to remember about epoxy colorant is that a little goes a very long way.
   I find that most seams require three or four mixed colors to get them looking good, and some even more. If you start down the wrong color path, throw away the batch and start over. A little wasted epoxy is better than an ugly seam.
   Another good reason for using as little color as possible is that granite surfaces have a relatively translucent look. The more colorant you add to your epoxy, the more solid-looking it becomes.
   A solid seam with the wrong color hue can stick out like the proverbial sore thumb. The exception to this rule is black stone; use too little colorant and the result is a washed-out gray/green look. Use plenty of colorant for black.
   Every installer, with some experimentation and experience, will find adhesive combinations that are cost-effective and work well. And, new products and tools continue to come out annually.
   Once you have a comfortable knowledge base to work from, experiment with new adhesives and combinations. You may even find things that work better.
   Jason Nottestad, a 12-year stone industry veteran, is co-owner of Wisconsin-based Midwest Template Services.

This article first appeared in the September 2006 print edition of Stone Business. ©2006 Western Business Media Inc.