Step 1 Use a scraper or a knife to scrape away any old caulk, grout and dirt. Step 2 Clean the surface with detergent. Step 3 Apply masking tape to both sides of the area you want to caulk (to prevent the caulk from spreading into other areas). Fill the joints with the caulk. Maintain a steady pressure and move at a rate that will fill the crack evenly. Step 4 Wet your fingers with cold water (so that the caulk won’t stick to them). Smooth and level the caulk with your wet fingers into a neat, slightly concave bed. (Plastic gloves can also be used, but you will need to wet them) Step 5 Peel off the masking tape and discard it.