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We did this Corian top a couple years back and the customer wanted this Kohler undermount sink that has an integral drain board. We have been using sink fastners from Integra that have a threaded stud on a mesh plate that get epoxied to the bottom of the deck and they have and adhesive called composite bonder to complete this.
They homeowner called recently to say that the front right corner of the sink has started to drop down from the countertop.
I went out to look and it has droped about a 1/4″. While I was there the dishwasher was running and I put my hand on the counter and felt it to be very warm right in the area the sink corner had dropped. I pulled the dishwasher out to find that the threaded sink fastners had come off the countertop in this area. I was able install a few more fastners and also brace the sink with some wood supports to keep this from happening again. I had asked about how long ago they noticed the sink had dropped, they said not long after the new dishwasher was installed. I can only assume it was the heat that caused the adhesive to fail, I’m wondring if they might be able to have the dishwasher operating temperature adjusted?
I would agree, probably due to the heat. have you ever used the brass inserts. They are better on solid surface because they are embedded into the material and glue can’t fail.
Bonded sink fasteners are a reliable method of attaching sinks to Solid Surface, Quartz & Natural Stone countertops providing they are properly installed.
On Solid Surface and Quartz, each fastener is tested to hold no less than 250 lbs. There is some variability but failure mostly occurs closer to 300 or 350 lbs and it is usually the fastener that separates at the weld.
Integra recently introduced a new style of under-mount fastener that uses a drilled plate where the bolt or “Stud” is dropped in from the back and then welded in place. This bolt will hold even more weight and it does not rely on the weld to hold the stud in place.
That leaves us with four more considerations;
1. Load rating
2. Substrate and surface preparation
3. Adhesive composition, mix and cure
4. Heat failure
Assuming the sink weighs less than 1000 lbs when full (including the weight of the homeowner standing in it) and that at least 4 bolts were used, the system should be adequate to carry the load. Next, we need to make sure the surface was prepared properly. For Solid Surface, this means just a light sanding with coarse 80 /100 grit abrasive to provide some tooth and to remove any possible contamination. The same applies for Quartz.
Stone counters need to be ground with a diamond wheel to remove the muck left behind from the wire saw process. If you don’t grind the back of stone before attaching the fastener it will hold about 40 lbs. Next, wipe the area with Alcohol or Acetone to remove any contamination or moisture. Then it’s ready to go.
The glue used should be a toughened methacrylate, toughened epoxy or vinyl ester. They each have holding power but beware of fast cure (5 min) epoxies as they are quite brittle and will let go if impacted. Integra recommends RTP-01 because it cures in 10 / 20 minutes, forms a gel when mixed so you can use it upside down, has excellent impact resistance and will hold about 250 to 300 lbs per bolt.
Caution: It must be mixed properly to perform properly. If you use RTP-01 from a 2-component cartridge, remember to purge between applications. The glue in the static mixer should come out looking like a soft gel. It can come out looking watery if you leave it sit for a few minutes between applications. If you see this, just purge a little until it forms a gel again then carry on. The watery glue has just separated from sitting in the static mixer partially mixed (it wont stick).
Wait until the glue sets before applying load. This takes about 20 minutes depending on temperature. If you apply load too soon you will see the bolt pull free right away. (Helpful hint; Check the glue from when you purged the tip. If it’s cured, so is the glue under the counter)
Heat: If the fastener failed due to heat, it would be the first report of in 7 years. That’s not to say it couldn’t happen but it’s not very likely. The glue softens as it’s heated but up to 150 degrees, it changes very little.
If you think the temperature is higher than that, we can make a test in the lab to determine the maximum recommended temperature.
Posted By Paul on 29 Nov 2010 12:01 PM
Bonded sink fasteners are a reliable method of attaching sinks to Solid Surface, Quartz & Natural Stone countertops providing they are properly installed.Heat: If the fastener failed due to heat, it would be the first report of in 7 years. That’s not to say it couldn’t happen but it’s not very likely. The glue softens as it’s heated but up to 150 degrees, it changes very little.
If you think the temperature is higher than that, we can make a test in the lab to determine the maximum recommended temperature.
Paul, Heat is my best guess. Like I said we put this top in back in Feb of 2008 and and it wasnt until after this new dishwasher was installed that this happened. The homeowner mentioned they noticed the countertop is quite a bit warmer now when the new dishwasher is runner then when the old one was in place. On this sink we used 12 fastners and it was just the 2 in the front right corner that let go. As far as the temperature goes, l I really dont know.
Steve,
From the picture you posted, it appears to me that you may not have used enough of the glue around the bolt’s base plate. The bolt pulled away pretty cleanly pointing to cohesive failure of the glue. In other words, the bond to the countertop is completly intact which tells me the glue probably cured and bonded as it is intended to. What I think has broken is the glue itself.
The key to making these fasteners remain intact is to use enough adhesive and fully encapsulate the base. They are zinc plated and there is very little bond strength between the glue and the metal base plate of the bolt. You are using a mechanical bond by way of encapsulation.
I use a popsicle stick to work the adhesive around and make sure there is a good amount of material all around the plate. I then flattening out the glue that pushes through the holes.
If there was a real thin layer on these two particulat bolts and they were subjected to impact during the new DW install-they could’ve easily broken free.
In most cases, the hardened squeeze through will stop the fastener from letting go. The problem is that the glue doesn’t actually stick very well to the zinc coated fastener – you are relying on the squeeze through not to break off- not the adhesive bond to the fastener.
Therefore, you can achieve the strongest bond by working the excess around and flattening it out to fully encapsulate the base plate.
Chad, I do apply the glue like you explained and also have done what Kelsey has and add more to the surface. I know the fasteners have a lot of strength and have been using them for a few years with never any issues. ln this case I’m at a lose. The fact that the only difference since the job was installed was the new dishwasher which the homeowner admits does cause the counter to get quite a bit warmer then the previous dishwasher. This sink is unique in the fact that it extends over the top of the dishwasher so thats reason I think its the heat, but I could be wrong.
Steve, one day while installing a sink I let the new guy finish attaching the sink. When I went back in , I noticed 2 of them cracked. He thought snug, meant tight, so he took pliers to the wingnuts.
With that said, it is possible, the wingnut was overtightened, even by hand and was cracked from day one, just a little. Then the added heat stressed it a little more.
However, I use 8 clips on my sinks, so I’m not sure if one failed the sink would sag…
I always carry some of those heat indicator strips with me and if you think you have a heat related problem stick one where the problem is tell the customer to put the appliance on for 1/2 an hour then look at how many cells have popped then you can tell the customer what there problem is and provide a solution and charge them for your time.
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