First of all, get a foam sealer in an aerosol can. There are many brands available in the market. You can even seek help from the shopkeeper. Describe your problem, and ask which spray would be best for you. After getting a can, attach the extension straw. This will help you reach the tiny corners of the sink.
It is the time to identify the areas that require treatment. Turn the tap on and mark the holes or gaps. Spend some time to find out all the problems. Such gaps or holes are usually found in the wood where the plumbing fixtures come from the basement of the sink.
After identifying all the areas, spray the foam on each hole. There is no need to spray it at once, because it expands after touching the surface. Spray only a little at a time, and increase its quantity only if required. You can use a wooden stick to even the surface of the foam.
Leave the form to dry. When drying, foam should not be touched. The foam will turn into a non-tacky form within 15-20 minutes. However, it may take 06-08 hours to harden completely. Don’t turn the tab on even for a second during this time. Water won’t let the foam dry quickly.
Once it is dry, analyse the area properly. If you have sprayed too much foam, you can remove the excess by cutting it with a sharp knife.
Now turn the tap on, and see if there is still any leakage. If yes, you are required to spray a little more foam on the specific areas.
Don’t forget to paint the foam, so it matches with the sink cabinet.