Replacing a bathroom undermount sink

[elmaur]

See pics. Anyone with firsthand experience doing this. The sink, countertop, cabinet were installed about 15 years ago. The sink has hairline cracks. The adhesive used to adhere sink to the countertop is very hard and dense. I tried working through it with a putty knife without success. I think there is a chance the countertop would crack if I got more aggressive with it such as using an oscillating multi-tool. Any suggestions?

 

[Twowaxhack]

I’d remove the clips. I have no idea what adhesive they used. Try to identify it.

Maybe a dremel with a diamond cutting wheel, run the joint with it.

 

[elmaur]

I’d remove the clips. I have no idea what adhesive they used. Try to identify it.

Maybe a dremel with a diamond cutting wheel, run the joint with it.

I loosened the clips. The adhesive is hard to see but looks grayish. i don't think a dremel is the right tool. The reach needed from the edge of the countertop is about 1.5 to 2 inches to get through the adhesive. An oscillating multi-tool has the reach but could crack the countertop. Anyone?

 

[Twowaxhack]

I’d use a dremel with a diamond wheel and cut from the bowl side and the underneath side. Or a small grinder with a diamond wheel.

It would be tedious but I wouldn’t break the top. It might be epoxy.

Goodluck.

 

[pasadena_commut]

A little searching suggests that sinks mounted like that normally only have silicone sealant around the edge, with the weight being held by the clips. Various things will soften/dissolve that sort of sealant, but I worry that it might also dissolve the coating on the bottom of the granite. Worse, if the "granite" is some sort of synthetic, it might come apart in chunks.

I would ask whoever supplied that countertop material, or if that isn't known, some other supplier of that material, for some pointers.

If push comes to shove, the OP could always test whatever solvent is used on a small area of the bottom of the countertop. If that doesn't damage the surface, then apply it to the ring.

The edge of a hot razorblade might go through the ring. It wouldn't hurt real stone, but it would probably also go through some synthetics which look like stone. (I used to have a soldering iron with an exacto knife blade where the element usually fits. It was used in a jig to flatten the ends of plastic optical fiber in an alarm system. Like this:

https://www.instructables.com/Make-a-Hot-Knife-using-a-soldering-iron/
)

 

[havasu]

If you hold your oscillating tool flat to the granite, I would think you'd be OK. If worst comes to worst, the slab breaks and for a few hundred bucks, you can replace it.

 

[elmaur]

I’d like to try anything to avoid breaking the counter top. To replace the countertop would be at least $500 installed and about at least another $500 to replace the custom sized mirror adhered to the wall with mirror mastic. It sits on top of the 4” high backsplash which would need to be replaced. Not a desired outcome.

 

[Twowaxhack]

https://www.dremel.com/us/en/p/545-26150545ab
They make them in 1.5” diameter.

 

[Twowaxhack]

Here’s a sure solution.

https://millnertools.com/products/2-electroplated-diamond-angle-grinding-wheel
There’s no magic lavatory mystery adhesive remover available.

 

[elmaur]

The 1.5” diameter would get about half the way through. The sink is larger than the edge of the countertop opening by about .5 to .75 “ all around but it might just make it easier to get the rest of the way with a putty knife.

 

[Twowaxhack]

The 1.5” diameter would get about half the way through. The sink is larger than the edge of the countertop opening by about .5 to .75 “ all around but it might just make it easier to get the rest of the way with a putty knife.

Cut from the top and from the bottom. That equals 1.5” . You want a thin wheel, the adhesive probably isn’t thick.

Or choose a 2” diamond wheel.

Break the sink out about 2” down from the top to get it out of the way. Duct tape the broken edge with multiple layers of tape. Tap gently….. wear safety gear. China is sharp when it breaks. Duh !

 

[pasadena_commut]

Break the sink out about 2” down from the top to get it out of the way.

If possible put an open cardboard box which is wider than the sink underneath first to catch all the pieces. Ideally its top would be flush with the bottom of the countertop around the sink. Then break it out from above. Once all the sharp bits are in the box it can be squished down and taped closed and placed in a trash can. Don't use too thick a box or it won't be easy to mash it into a smaller volume.

In my experience when disposing of shards it is best if they are wrapped up like that, or this will be the one day the truck drops sharp bits from the can all over the street.

 

[elmaur]

I was able to work through most of the caulking around the sink with a putty knife. The rest I will get when I disconnect the drain pipe and the bowl will separate at the cracks leaving only about 30% of the bowl to remove.
Any suggestions how one person can get the new sink mounted, given the weight of the sink? I have some ideas like hoisting up with a strong rope attached through the drain hole with a block of would connected to the rope to protect the sink. I would just have to get it to where the clips can support it, apply the caulking and then tighten the clips.

 

[Twowaxhack]

I’ve used two 2x4’s, and a piece of threaded rod with nuts and washers.

One short 2x4 goes under the sink with a hole in it so the threaded rod can pass through the drain hole and 2x4.

The upper 2x4 spans the countertop and also has a hole so the threaded rod can pass through.

Then you apply your sealant of choice and make it all sandwich together for 24+ hrs.

Some people simply cut a wood support then wedge it under the drain hole.

 

[elmaur]

Thanks for the suggestion. Very cool.