Sink replacement, cultured marble countertop

QUESTION: My home was built in the mid-70s. The bathroom countertops are made of a synthetic material that looks like fake marble. I need to replace a porcelain bathroom sink. It is installed from under the countertop with four clips and some kind of glue or sealant. I can get the clips off ok, but it is really stuck to the bottom of the countertop. How can I get the sink “unstuck” without damaging the countertop? Once I get the sink out, I’d like to install a drop-in type sink. What kind of sealant should be used around the bottom of the sink?
Ron Hills
ANSWER: “It sounds like you have a cultured marble counter top with the lavatory sink caulked to the bottom of the counter,” says Vince McDonald of McDonald Plumbing, Heating and Air Conditioning in Sacramento.
“I suggest following these steps to remove the sink:
1. Remove the four support clips under the sink.
2. Take a razor knife and carefully cut the caulking seal from the inside of the sink. You may not be able to cut all the way through the caulking, but that should not be necessary.
3. Now take a chisel or large screw driver and carefully drive it between the sink and the counter top. Don’t try to separate it in one spot only. Rather, work it around the rim in several places so that you minimize the stress on the counter top. The counter top can break, crack or chip so don’t be too reckless. Take your time and the sink should drop out with this method.
“The new lavatory sink that you describe is called a “self rimming” sink, he says. The lip of the sink will sit on to of the counter, which differs from the one you are removing. These sinks usually come with a small tube of latex caulking,” McDonald says. “If your sink doesn’t come with caulking, pick up a small tube of tub and tile latex caulking. It is not a durable as silicone caulk, but it is much more user friendly and makes for a nice professional job.”
“After you caulk the sink to the counter, use a wet finger in a wiping motion to push the caulking into the gap between the sink and the counter. Follow up with a wet rag over the top of your finger, in the same motion, to make a nice clean joint and remove any excess caulking. The clean up with this caulking is a snap, because it is performed with water.”

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