My kitchen sink has fallen, and it can't get up!
March 21, 2008 4:00 PM   Subscribe

What kind of adhesive is used to secure an undermount kitchen sink to the underside of a countertop?

I have an undermount stainless steel kitchen sink suspended underneath a Corian countertop. While a normal kitchen sink rests on the surface of a kitchen countertop, an undermounted sink is suspended from below, attached to the countertop using a special high-strength adhesive.

Today, when I came home from work, I found that one of the sink basins dropped; something happened with the adhesive, and the basin came loose and fell from underneath the countertop. This isn't supposed to happen, but considering the seemingly weekly loads of fail my moneypit of a house have been giving me the past year, I'm not surprised.

There's a special type of adhesive that is used to mount stainless sinks underneath Corian countertops. However, a half hour of searching through Google found nothing more than the fact that ... well, a special kind of adhesive is used. What kind of adhesive, though ... no such luck. Anyone handier than me any ideas?
posted by elmwood to Home & Garden (9 answers total) 1 user marked this as a favorite
I believe most undermount sinks are mainly secured with screw-in clips (even into stone or solid surface). To my knowledge the adhesive is not the main method of securing the sink, but instead provides some adhesion while being a water barrier. Do you know the sink brand? The attachment instructions usually come with the sink, not the counter.
posted by true at 4:08 PM on March 21, 2008

ditto true
the sink is held by clips, with caulk (not adhesive per se) to seal it
posted by anadem at 4:11 PM on March 21, 2008

You might want to try a 2 part epoxy, you should be able to go to your local hardware store and get something that will come as two seperate ingredients, the resin and the catalyst. I don't know any by name specifically but epoxy is usually as hard as nails. When you get back home make sure the portion of sink that attaches to the counter is clean; it might not be a bad idea to scour it with some steel wool to give it a little bit of texture. Also make sure the underside of the counter is clean and free from moisture, mold, or whatever else may have built up. Again hit it with some steelwool to make sure its clean and a little rough to affix properly. For the best results, this is probably a 2 person job; after you affix the sink, rig up some kind of mount for the sink to stand on for about 24 hours so the epoxy will set and cure. And don't touch it for a day or so.
posted by Scientifik at 4:13 PM on March 21, 2008

There's no way any adhesive alone would be strong enough for the long haul. What you're seeing is shoddy construction, probably to save money.
posted by Class Goat at 4:58 PM on March 21, 2008

Yup. THere should have been cleats or a cast-in rail to bolt the sink bowls up under the counter, and the seal would have been plumber's putty. What class goat said. You still under warranty?
posted by notsnot at 5:04 PM on March 21, 2008

As most everyone says above, it's screw on clips (actually very small clamps) that do this. It works better than any adhesive since the sink will naturally shift around a bit. A full sink is very heavy, and all that hot hot, cold cold leads to much expansion and contraction.

Clear silicone sealant is usually used around the rim of a sink so that water doesn't seep under. It also softens the sounds a bit. That works because the silicone stays soft forever, and will give a little with the natural shifting around of the sink.

I wouldn't use any adhesive that hardens, like epoxy. Because it hardens and won't handle the moving around that sinks do, it'll crack over time.
posted by rokusan at 5:06 PM on March 21, 2008

I would not use any super adhesive, you may want to remove the sink someday. What a drag if you had to replace the entire countertop because you couldn't remove a dented or stained sink.
posted by Daddy-O at 6:00 PM on March 21, 2008

Like everyone said before, its little clips that hold the sink in place. But if you decide to put it in permanently, an F-26 construction adhesive is thick, messy and very strong.
posted by shinynewnick at 6:45 PM on March 21, 2008 [1 favorite]

If I would want to use a glue for this kind of job, I would use some kind of marie sealant/adhesive. Marine as in yachts, boats and lots of salt water. The stuff can be expensive but it is _strong_ and stable under many conditions. Most of them are also sealants, which is a bonus in the kitchen area. I believe some of the best are polyurethane based (PU).

This type of glue is probably not the glue used by kitchen builders, it is better. Most crafters/builders are very conservative.

I am not a yacht owner, but buy tis stuff from my local DIY Sikaflex, I don't know if they sell it where you are.
posted by mmkhd at 12:08 PM on March 22, 2008

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