Clean the gap and remove dust, debris, and old loose caulk
Make sure the baseboard and wall are dry
Choose paintable caulk for interior trim
Cut the caulk tube tip at a 45-degree angle
Puncture the inner seal of the tube
Load the tube into a caulk gun
Apply painter’s tape along the wall and baseboard if desired
Hold the gun at a steady angle and apply a thin, continuous bead along the gap
Move slowly and keep even pressure on the trigger
Smooth the bead with a caulk-smoothing tool or a damp finger
Remove excess caulk before it dries
Pull off painter’s tape while the caulk is still wet
Let the caulk cure according to the product instructions
Paint over the caulk after it has fully cured if needed