All undermount sinks are secured to the underside of the counter top using caulk, as this is a water proof sealant that will need to be applied to the sink before and after it is installed. By applying caulk before you install your sink will prevent any leaks or water seeping through the seam between the counter top and the sink. Before applying caulk you will need to make sure that everything is dead leveled and flush when the sink sits on the counter top. This article will show you how to apply caulk to your undermount Sink.
You can purchase caulk from most local hardware stores, you will also need a 2 by 4 piece of wood a bar clamp and c-clamp a undermount sink clip and adjustable wrench. Epoxy and a clean sponge to finish the job off.
Apply caulk sealant along the top of the sink or the lip that will eventually sit on the top of the counter, don't apply too much just a line of sealant along and around the edge will do. Now with your 2 by 4 place this across the opening of your sink vertically. To center your sink in it's proper position ,push the sink up against the bottom of the counter top so it is centered within the hole. Now you will need to insert a bar clamp through the bottom of the drain and sure it to the 2 by 4.
Next to the sink you will see the bolts aplly a little amount of epoxy to the bolts. Now insert the undermount sink clip and then tighten it with your adjustable wrench. Now it is just a matter of letting the whole thing dry for at least 24 hours before applying the finishing caulk. After the 24 hour drying period once again run a line of caulk along the edge where the sink meets the counter top, this will make double sure that no water will leak through between the sink and counter top.
Now simply run your finger along where you have applied the sealant to give it a smooth look and finish and wipe away any access caulk with a wet sponge and that's pretty much it. Let it dry for another 24 hours and your done. Test your work by adding a little water around the edge of the sink and check underneath for any suspect leaks, you should be able to locate the leak and easily ad more caulk if necessary. As you can see the process for adding caulk to a undermount kitchen sink is quite straight forward and should take no less than a couple of hours to do.