One of the final steps to crown molding installation involves running a bead of caulk in the gaps between the molding and the walls and ceiling. For new installations, caulk should be applied before painting. For the purpose of upkeep, caulk is used to fill in spaces that develop due to the natural expansion and contraction of the decorative wood trim. It covers up gaps while staying flexible, allowing wood room to adjust. Knowing how to properly run a bead of caulk is a basic skill that will serve you well in many areas of the home. If you've never done it, this is as good a place to start as any.
Step 1: Load Caulking Gun
Once your crown molding is tacked to the wall and ready for finishing, it's time to apply the caulk. Hold the caulking gun by the handle and with your thumb, press the steel rod release and pull the rod all the way back. Place the unopened tube of silicone caulk into the housing of the caulking gun. The tip of the tube of caulk should fit through the slot at the front of the housing. Once the tip is through, position the back end of the caulk tube over the circular pressure plate attached to the steel rod. Move the steel rod forward so the tube is held in place without too much wobbling.
Step 2: Cut Off Tip
Using the utility knife, cut off a small section of the tip of the tube at a downward-facing 45-degree angle. The resulting hole should be about 1/4 inch in diameter.
Step 3: Position the Ladder
Depending on where in the room you will start, move the ladder to a convenient spot whereby you can start a bead and run it as far as possible. In other words, if you're starting in a corner, don't set up the ladder directly under the corner, but a little way from the wall. It's always easiest and least wasteful to run a continuous bead of caulk wherever you can.
Step 4: Run Your First Bead of Caulk
Once ready, pump the trigger of the caulking gun until you feel the force of the pressure plate against the back end of the tube. At this point. caulk will start to squeeze out through the opening in the tip. Applying even pressure on the trigger, run a continuous bead of caulk along the gap between the crown molding and the wall.
Step 5: Smooth Bead with Your Finger
Next, run your forefinger over the fresh bead of caulk in order to smooth it and even it in relation to the adjacent surfaces. Your finger is better for this than a rag because you have more control and can feel the effect. Use the clean shop rag to wipe away an excess caulk that may have ended up on the wall or molding.
Step 6: Repeat for Other Gaps
Repeat this process for all gaps. Keep in mind that the caulk may continue to spew out of the tip even when the trigger is not pressed. Hold or set the gun upright in between applications so as to waste as little as possible.