Is it silicone adhesive that kitchen and bathroom remodelers use to "glue" a porcelain sink to the underside of a granite countertop around the perimeter of the cutout? Something else?

P.S. I know there's also a kind of screw attachment; I'm interested in the chemical composition of the substance since I want to detach the sink from the countertop.

  • 1
    I don't know enough to write an answer, but I believe if clips cannot be used, a special two-part epoxy is used to suspend the sink and then it's finished with silicone for a seal. I believe construction adhesive or silicone adhesive are used to add strength to mechanical mounts when heavy sinks are mounted to stone countertops with clips.
    – jay613
    Commented Feb 18, 2022 at 19:56
  • 1
    @jay613 To a point, but for the largest part used to seal the sink against the countertop. The "glue" part is a handy side-effect I think.
    – gnicko
    Commented Feb 18, 2022 at 22:45
  • You can get "silicone sealant remover" it it turns out to be that. Can you see any of it squished out from the inside? Commented Feb 19, 2022 at 16:08
  • Where are you? I suspect this is a regional thing, as my experience in California is exclusively with 2 part epoxy -- never just silicone. (Though silicone always follows in the crack.) One last question: are you trying to preserve the sink you're removing? Life would be easier and more smashtastic if you didn't need to save the sink. Commented Feb 19, 2022 at 16:20
  • @AndrewMorton no squishing; it was a pretty neat job.
    – mr blint
    Commented Feb 20, 2022 at 14:08

3 Answers 3


Most likely it's silicone. You should be able to cut it with a razor/knife to free the sink and then scrape/peel it off completely once the sink is out of the way.

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    Silicone is used because it also happens to make a nice water tight barrier to the water that will try to work its way between the bowl and countertop.
    – FreeMan
    Commented Feb 18, 2022 at 17:24
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    It'll get in there somewhere!
    – gnicko
    Commented Feb 18, 2022 at 22:44
  • @FreeMan - that's all it's for. Other than it'd get gross.
    – Mazura
    Commented Feb 19, 2022 at 4:36
  • @gnicko - agreed. And it is always fail so never fill up your sink to the countertop.
    – Mazura
    Commented Feb 19, 2022 at 4:38

You can get silicones that are also adhesives. Best of both worlds.
Just search "silicone adhesive".

A selection from a UK builders' merchant chain.

  • Does this mean we can dispense with L-brackets or all-round strapping, which usually function as primary support for the sink?
    – P2000
    Commented Feb 18, 2022 at 20:36
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    @P2000 you could risk it, I would not.
    – Solar Mike
    Commented Feb 18, 2022 at 21:46
  • Or....are they adhesives...that are also silicone?
    – gnicko
    Commented Feb 18, 2022 at 23:47
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    @SolarMike indeed I wouldn't. That begs the question, then why use silicone adhesive at all?
    – P2000
    Commented Feb 19, 2022 at 3:08
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    Don't. That's not what hangs a sink with 100 lbs of water in it. That's what keeps it from leaking.
    – Mazura
    Commented Feb 19, 2022 at 4:35

Whatever it is it's softer than both granite and porcelain

Just use a wire to cut through it.

  • Is there a kind of thin abrasive wire that works like a saw blade? Or just any thin wire? I would like to preserve the sink, BTW.
    – mr blint
    Commented Feb 20, 2022 at 13:05
  • 1
    Any thin high tensile strength wire. spring steel works well.
    – Jasen
    Commented Feb 20, 2022 at 13:09
  • “Pvc pipe cable saw” would be your best bet. (Even Home Depot carries a few.) But I’m not convinced that it’ll work well if you’re up against epoxy. Commented Feb 20, 2022 at 15:27

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