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Top mount sink with no visible sealant

Posted by tony_james (My Page) on
Thu, Aug 30, 12 at 21:28

Hi all

I keep reading that one of the main disadvantages with a top mount sink is that there is a visible join between the sink and the counter top. This seems to be either a silicone or a caulk material. The issue people note is that dirt gets caught in this seal and cannot be cleaned out.

The funny thing is, my parents have had a top mount sink for 20 years, and there is neither a visible sealant nor any hint of dirt between the sink itself and the counter top at all. They just asked their plumber how the sink is sealed, and the plumber told them he used a material like Blu Tack which is underneath the 'lip' or 'rim' of the sink.

Is this an unusual practice? Or have I gotten myself confused with too much research? It seems to fix all of the mentioned issues, but I can't help wonder why everybody else isn't doing this? We've had zero issues with our sink in 20 years.


Follow-Up Postings:

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RE: Top mount sink with no visible sealant

I am getting top mount simply because I have read that the caulk/seal is harder to keep clean on the undermount.
I think if you dry and rinse regularly, neither are a problem. Wet = mold and it can happen regardless of how it is mounted.
My DH does not regularly clean and wipe the sink area, so for sanity's sake, the top mount will be easier to use a bleach stick if I need it and to have it air dry faster.
It is my preference.


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RE: Top mount sink with no visible sealant

Our top-mount Kohler sink of 20 years has no crud or gunk growing next to it. After it was installed, I filled in a few places with a clear silicone caulk, and it has been great ever since. I keep an eye on it, etc. My sister has an undermount Kohler, I don't know how old it is, and I can see the black crud growing down from the negative reveal. Grossssss.......


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RE: Top mount sink with no visible sealant

Any ideas on the sealant being applied under the rim of the top mount sink instead of at the outer join between the sink and counter top?


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RE: Top mount sink with no visible sealant

We just had our Kohler cast iron sink top mounted a few weeks ago. We were worried about the caulk around it, but we cant see it hardly at all.

The installer put the silicone around it, then sprayed something from a bottle around the sink and wiped away the excess silicone. I asked what it was and he said Denatured alcohol. He said it cleans up all the extra silicone and makes it look nice. Our seams and the sink all look great since they did this step.


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RE: Top mount sink with no visible sealant

That's interesting to know paulflyboy.

I guess the question running through my mind is how my parents' sink ended up with no seem visible anywhere...no matter how small...since it's actually underneath the rim of the counter and not where the two surfaces meet.

I'm just wondering why this isn't the standard for installing a top mount sink?


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RE: Top mount sink with no visible sealant

The industry standard for sealing a topmount sink has always been plumber's putty. It is superior to silicone in most respects for that use. You just roll out a rope of it, place it under the rim of the sink, drop the sink in, tighten the clips, and then remove the excess putty that is squished out. Simple, and plumbers putty never hardens so always maintains a seal if you've used enough of it. It is NOT advisable to use it with natural stone as it's oil based and the porous stone can pull the oils out of it and become stained.


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RE: Top mount sink with no visible sealant

That's great information, thanks live_wire_oak! I didn't even know the name of it until you told me :)

Well I will be using CaesarStone counters, so is it applicable for me?

Is there still a danger of dirt getting trapped between the sink rim and the counter? Tiny particles of dirty would logically get in somehow but looking at my parents' sink I just don't know how it stays so clean!

What if you want to change the sink in the future? How do you remove it later on?


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RE: Top mount sink with no visible sealant

As LWO said, plumbers putty never hardens . You just remove any clips underneath, perhaps stick a putty knife under the seam, and pry/lift it up.


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RE: Top mount sink with no visible sealant

Hmm, just found some information elsewhere on the Internet that apparently Blanco advise against using plumber's putty on their Silgranit sinks.

I guess that explains why it always seems to be silicone then.


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