Saturday, December 19, 2015

Repairing a Moenstone Composite Granite Sink

A few years ago we remodeled our kitchen and went with an undermount Moenstone sink.

This Thanksgiving I noticed a hairline crack in the bottom. We called Moen and they were willing to give us money or a new sink as part of the warranty (which is great!), but the sink is undermounted. We'd probably need to remove the entire countertop to put a new one in, and Moen no longer makes them.

Our choices were either to repair it, install a drop in sink, or maybe find another undermount sink with a similar profile. A new undermount probaby requires taking off the countertop and recutting.  A drop-in requires recutting the counter.  Ugh!

So... I researched how to repair composite granite sinks.  I didn't find a whole lot of information. Some people suggested epoxy.

We are one day (2015-12-19)  into our repair, still waiting for the glue to set, but I wanted to document my process. The foundation for our repair is a Simpson Strong-Tie product I found for repairing cracks in cement, CRACK-PAC. It has the viscosity of room temperature syrup, which I thought was ideal for trying to work into a hairline crack.

Here are materials & tools I used:
You will only use a small amount of the CRACK-PAC, so you might scout out ahead of time for cracks in your driveway to fill when you are done.  The epoxy has about 1 hour of working time.  It will get hot as it cures, which will be noticeable if you leave it in the tube.
  • Clean the crack as best you can. Hopefully you caught it early enough it doesn't have a lot of goop in it.  Use hydrogen peroxide and/or the alcohol to try to clean out the crack.  Use the alcohol last as it evaporates better than water.  DO NOT USE SOLVENTS.  As best I can tell, the sink is a mixture of acrylic resin and granite.  ACETONE EATS ACRYLIC!  TAP plastics even cautions against isopropyl and acrylic, but I didn't think it would harm it for a short application. Moen cautions "DO NOT USE: Abrasive cleansers or materials; abrasive scrub pads; alkali cleaners such as ammonia; concentrated solutions of chemical descaling agents; lacquer thinner; steel wool or soap filled steel wool scrub pads; undiluted bleach; drain unblocking chemicals that recommend filling the sink with water. Do not pour paint or paint cleaning materials in sink"
  • Dry the sink.  Use the hair dryer and/or the 500 watt light.
  • Once the sink is super dry, mask the crack with the tape, leaving about 1/2" on either side of the crack.  The masking tape will make a shallow channel that helps keep the epoxy in place as you work it in.
  • Mix the CRACK-PAC according to Simpson's instructions.  (Our tube leaked a little around the valve even with the rubber cap, so be careful.)
  • Using the caulking gun, apply some CRACK-PAC to the length of the crack
  • Work the glue into the crack as best you can with the putty knife -- observe under the sink to see if any is leaking through (you put down a towel, right?)
    • You can also try to suck some glue down through with the vacuum.  Note: This may get glue into your vacuum!
    • I did this step for about 15 minutes -- just scraping over the crack with the knife trying to push the glue into the crack.  
    • I was not able to see it leaking through the entire crack -- only in the middle.
  • Once done, pull up the tape and wipe up the excess glue with your dry cotton rags.
  • Now, go fill in cracks in your driveway.
  • As a backup measure, we also used the masonry epoxy.  I used about 1/3rd of each jar to epoxy the crack from the back side.  It isn't pretty but may help.
  • Now wait.  CRACK-PAC suggests 24 hours.  Since it changes color in a couple days more than that, you might want to wait longer.  (I'm not sure how long we'll wait.)
  • An additional step we did was to support the garbage disposal with blocks of wood from below.  We hope that this extra support from the bottom would help keep the crack from spreading further.
  • Turn the water off at the sink for at least 24 hours.  Don't put anything in the sink until you are sure the epoxy has fully cured.
I'll post periodic updates on our fix... please let me know if this was helpful!



  • 2015-12-20 - We've turned the water back on again and are allowing the sink to get wet.  Right now we are avoiding putting anything else in the sink.  When the CRACK-PAC dried I noticed a raised ridge along the length of the crack.  I'm guessing this means the epoxy expands a slight amount, which is actually ideal.  The slight ridge doesn't bother me and has the advantage that I can track any future crack growth.