How to Caulk a Bathtub Properly

Remove old caulk completely, clean and dry the area thoroughly, apply new caulk in one smooth motion, then tool the bead for a professional seal.

  1. Strip Everything Away First. Use a caulk removal tool or utility knife to cut away all old caulk from the joint. Scrape out every bit of residue from the gap between the tub and wall. Old caulk prevents new caulk from adhering properly, so this step determines your project's success.
  2. Scrub Down to Bare Substrate. Wipe the entire area with rubbing alcohol or bleach solution to remove soap scum, mold, and any remaining caulk residue. Let the area dry completely before proceeding. Any moisture or debris will compromise the new caulk's bond.
  3. Mask Edges for Precision. Place tape along both edges of the joint, leaving the gap exposed. This creates perfectly straight lines and prevents caulk from spreading onto surrounding surfaces. Keep the tape width consistent for professional-looking results.
  4. Angle Your Opening Right. Make the opening slightly smaller than the gap you're filling. Start with a small cut and enlarge if needed. A 45-degree angle helps control the flow and creates the right bead shape when you hold the gun at the proper angle.
  5. One Smooth Line Wins. Hold the caulk gun at a 45-degree angle and move steadily along the joint. Maintain consistent pressure and speed. Don't stop mid-way or go back over areas, as this creates uneven thickness and potential failure points.
  6. Shape It While Wet. Use your finger or a caulk tool to smooth the bead within 5 minutes of application. Draw the tool along the entire length in one motion, applying light pressure to push caulk into the joint and create a concave surface that sheds water properly.
  7. Peel and Wipe Fast. Pull the painter's tape away at a 45-degree angle while the caulk is still wet. Clean any excess caulk with a damp cloth immediately. Don't wait for the caulk to skin over, as removal becomes much harder.
  8. Let Time Seal the Deal. Keep the area dry for 24 hours minimum before using the tub. Full cure takes 7 days for most silicone caulks. Premature water exposure weakens the seal and allows water infiltration behind the caulk.