How to Remove an Undermount Sink

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by hmf-ny, Aug 7, 2007.

  1. hmf-ny

    hmf-ny New Member

    Aug 7, 2007
    I just bought a house with corian countertops. The kitchen sink is a 10 year old Blanco which is undermounted. The sink is white with lots of scratches revealing a black/grey core material...Very ugly and my wife wants it replaced.

    Underneath the countertop, I can see brackets holding up the sink that appear to be adhesively bonded to the corian countertop. (The brackets appear to be corian or similar material) I assume the sink is installed with silicone or similar adhesive between the lip of the bowl and the bottom of the countertop plus these brackets for additional support. I don't see any screws or fasteners.

    Can anybody suggest the best way to remove these brackets? Any idea what adhesive was used? Should I use a hammer to try to knock them off? Is there a solvent that can be used to break the bond? I would appreciate some advice!


  2. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    Often, these sinks themselves are Corian, and completely bonded to the countertop. But you said yours is a Blanco, and the description of the black base material showing indicates something other than solid surface, so it should be removable.

    Are there any screws involved in the brackets you mentioned?

    If it is just sealed to the top with silicone, you could try slipping a stiff putty knife between the sink and counter, being careful not to ding up the corian too much.

    You might contact a corian fabricator, as they would be familiar with the mounting technique which may have been used,.
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  4. FloridaOrange

    FloridaOrange Plumbing Designer

    Dec 2, 2005
    Plumbing Designer
    SW Florida
    You might want to get a corian contractor to do the install as well.
  5. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Nov 8, 2005
    Hansville, Washington
    I just had a Silestone countertop installed with a Blanco undermount sink. They drilled holes in the countertop and epoxied in some threaded inserts. Then used Polyseamseal caulk between the sink and the countertop, held it up with a bar clamp, and screwed the clips into the inserts. I'd guess the uninstall process would be to take off all the clips, and use the putty knife technique jimbo suggested to break the caulk seal. Corian, however, is different from the stone materials -- I like the idea of calling a Corian contractor to do the whole replacement.
  6. hmf-ny

    hmf-ny New Member

    Aug 7, 2007
    Thanks for all the info. Here's a picture of one of the clips. There is no fastener visible, so it would appear to be held up by some type of adhesive. After looking closely, the installation is so tight, I can't see a way to remove the clips withput lifting the whole countertop (which is L shaped and 14 feet on one side and 7 ft on the other).

    Attached Files:

  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    If I had to guess, I'd guess that those clips were installed to give the silicon a chance to set up. To get the sink off, you'll have to cut the lip off of them, then you have a chance of breaking it loose from the silicon. The clips are probably corian, and bonded using their special sets fairly quickly, so that it would then act as a clamp.
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