How to Re-Caulk a Glass Shower Door

Old silicone turns yellow, grows mildew and starts to leak. Re-caulking takes about an hour of work plus cure time, and the secret to a professional-looking bead is in the prep.

What you need

• Silicone remover and a scraper: CRL CRLSRK1T, CRL RS65 with CRL 51S blades
• Rubbing alcohol and lint-free wipes
• Painter's tape
• Silicone: CRL 33SMRC (or CRL RTV408C with brass hardware) and a caulking gun

Step by step

1. Remove the old silicone. Spray the old bead with a silicone remover like CRL CRLSRK1T, let it soften, then slice and scrape it off with a single-edge blade in a holder like the CRL RS65. Keep the blade low and flat so you don't scratch tile, stone or glass.
2. Clean the joint. Wipe away every bit of residue, then clean both surfaces with rubbing alcohol and a lint-free wipe. New silicone will not bond to old silicone, soap scum or moisture.
3. Let it dry. The joint must be completely dry. Give it a few hours (or overnight) after the last shower.
4. Tape both sides. Run painter's tape along both sides of the joint, leaving a gap the width of the bead you want.
5. Pick the right silicone. Use a mildew-resistant clear silicone like CRL 33SMRC. If any of the hardware is brass, use neutral-cure CRL RTV408C instead: standard acetic silicone can turn brass green.
6. Apply the bead. Cut the nozzle at an angle to the size of the joint, load the tube in a caulking gun like the CRL GA1204, and run one steady, continuous bead.
7. Tool and pull the tape. Smooth the bead with a wet finger or tool, then pull the tape right away, while the silicone is still wet, pulling away from the joint.
8. Let it cure. Keep water off it until it has fully cured. Follow the cure time on the tube label before you use the shower.

Common mistakes

• Caulking over old silicone. It peels within weeks. Always remove the old bead completely.
• Caulking a wet joint. Trapped moisture is the most common reason new silicone fails or mildews.
• Using acetic silicone on brass. It can turn the brass green; use neutral cure.
• Caulking the moving edge of the door. Silicone goes where glass meets a wall, curb or fixed panel, never on the edge of a door that opens. That gap needs a seal.