Caulk serves as an air and water barrier in all kinds of exterior applications, preventing drafts and leaks around windows and doors, vents, skylights, and all manner of openings. It also prevents water from seeping into cracks and causing damage.
In commercial settings, caulk is also a useful visual component, bridging gaps and hiding irregularities, and closing spaces where dirt and bacteria can accumulate. Caulking leaves clean, attractive lines along joints and corners.
When recaulking windows, the following guidelines should be used for best results.
1. Remove any old caulk from around the window frames. You will get the best possible seal by creating two clean surfaces for the new caulk to attach itself. After the largest pieces are removed, use a putty knife to remove any remaining bits of the material.
2. Prepare the surface of the windows. Repair any rotted material on or around the window before applying caulk. Remove any dirt, debris, and old paint that will hinder adhesion. Wash the area, but make sure it is dry before caulk is applied.
3. Place the tube in the caulk gun. Pull the notched rod back. Place the tip of the tube in the yoke. Turn the rod so that the notching mechanism engages. Squeeze the handle just enough to move the plunger cup securely against the end of the tube, inside the cylinder.
4. Cut the tip of the tube. Cut it at a 45 degree angle about a one quarter inch (0.6 cm) back from the tip. Use a slender nail to break the seal inside the tip.
5. Press the tip firmly against one corner of the window and apply caulk to the next corner in a continuous bead, just thick enough to fill the gap. Press the release mechanism to stop the flow of caulk. Continue around all 4 sides.
6. Use an flat object to smooth over the sealant and remove excess caulk. This process is referred to as "tooling."
7. Allow the caulk to dry for at least 24 hours. Though a "skin" will develop before it has fully hardened, the caulk may still be unstable and should be left alone. As long as it gets a chance to dry in place, your project will be a success.