To create a watertight seal around your bathroom sink, you will need to seal up any cracks, no matter how small, between the sink and the wall. Failure to seal these areas with a silicone caulk can allow moisture and water to slip behind the sink, damaging your wall.
Silicone-based caulks are available in a wide range of colours to match your sink or counter. These caulks can be applied to even the smallest space, filling it and keeping it water tight and looking great.
Clean the edge of the sink where it meets the wall. Remove any dust, debris or sink adhesives that may interfere with the bond of the caulk with the sink and wall. Allow the area to dry completely; the caulk cannot bond with moisture.
Cut the tip off of the tube of caulk with a pair of scissors. Aim to make the hole at the tip of the tube the same size as the gap you are filling between the wall and the sink. Insert the tip of the caulk tube into the front of the caulk gun, and push the back into the place. Line up the plunger on the back of the gun and tighten accordingly.
Squeeze a thin line of caulk into the gap between the sink and the wall. Keep the line even and consistent, with as few gaps as possible.
Dampen your index finger with water and use it to smooth the silicone into place, creating a tight, smooth and clean seal between the sink and the wall. Allow the silicone to dry for 24 hours.