Clean the gap thoroughly
Remove any old caulk or debris
Measure the width of the gap
Use backer rod for wider gaps
Apply painter’s tape along both edges
Choose a kitchen-grade silicone caulk
Cut the caulk tube tip at a 45-degree angle
Load the caulk gun
Apply a steady bead along the gap
Smooth the caulk with a caulk tool or wet finger
Remove painter’s tape before the caulk skins over
Let the caulk cure fully before using the area