Direct answer
Re-caulking a bathtub or sink takes about an hour of active work plus drying time. The job requires removing the old caulk completely, cleaning and drying the surface thoroughly, and applying a smooth bead of new caulk. Done correctly it lasts five to ten years. The most common reason re-caulking fails quickly is applying new caulk over old caulk or caulking over a surface that isn’t fully dry.
What you need
A caulk remover tool or utility knife, a plastic scraper, caulk remover solvent or rubbing alcohol, a caulk gun, 100 percent silicone caulk or siliconized latex caulk rated for kitchen and bath, painter’s tape, a damp cloth or paper towels, and a cup of water with a few drops of dish soap for smoothing.
Silicone caulk is more durable and water resistant than latex and is the better choice for tubs and shower surrounds. Siliconized latex is easier to apply and clean up and works well for sink edges and lower-moisture areas. Check that whatever product you choose is mold and mildew resistant since bathroom moisture makes mold growth on caulk a common problem.
Remove all of the old caulk first
This is the most important step and the one most people rush. New caulk applied over old caulk does not bond properly and will peel or crack within months.
Score along both edges of the existing caulk with a utility knife or caulk remover tool. This separates the caulk from the tile and tub surface and makes it easier to pull away in strips. Work slowly and keep the blade as parallel to the surface as possible to avoid scratching the tub or tile.
Pull the loosened caulk away by hand or with a plastic scraper. A metal scraper can scratch porcelain and acrylic surfaces so avoid it unless the surface is tile or stone. Work along the entire joint until all visible caulk is removed.
Apply a caulk remover solvent to any remaining residue and let it sit for the time listed on the product, usually 15 to 30 minutes. Wipe away the softened residue with a plastic scraper and cloth. Rubbing alcohol works as an alternative if a dedicated solvent isn’t available.
The joint needs to be completely free of old caulk before moving forward. Run a finger along the entire joint and feel for any remaining residue.
Clean and dry the surface completely
Any moisture, soap residue, or cleaning product left on the surface will prevent the new caulk from bonding. This step cannot be rushed.
Wipe the joint and surrounding area with rubbing alcohol to remove any remaining residue and degrease the surface. Let it dry fully. In a bathroom that has been recently used, this may take longer than expected. Running a fan or opening a window speeds up drying.
For bathtubs, fill the tub with water before caulking. A full tub adds weight that compresses the joint slightly. If you caulk with an empty tub and then fill it, the weight of the water opens the joint and can crack or separate the fresh caulk before it has a chance to cure. Drain the tub after the caulk has fully cured.
Apply painter’s tape for clean lines
Run painter’s tape along both sides of the joint, leaving the gap you want to fill exposed. This creates clean edges and catches any excess caulk that would otherwise smear onto the tile or tub surface.
Keep the tape lines straight and parallel. The width of the exposed gap should match the width of the caulk bead you’re going to apply, typically a quarter inch for most tub and sink joints.
Apply the caulk
Cut the tip of the caulk tube at a 45 degree angle. Start with a smaller opening than you think you need since it’s easier to go back over a thin bead than to clean up an oversized one. Puncture the inner seal with a nail or the tool on the caulk gun if the tube has one.
Hold the caulk gun at a 45 degree angle to the joint and apply steady, consistent pressure as you move along the entire length in one smooth pass. Move at a pace that keeps the bead consistent without stopping and starting. Stopping mid-joint creates uneven spots that are harder to smooth.
Apply the entire joint in one continuous bead if possible. For a bathtub, do each side as one pass rather than doing corners separately.
Smooth the bead
Dip a finger in the soapy water and run it along the caulk bead in one smooth pass, pressing lightly to push the caulk into the joint and create a concave surface. The soapy water prevents the caulk from sticking to your finger and allows a smooth, even finish.
Do this immediately after applying each section before the caulk begins to skin over. Silicone caulk skins quickly, so work in sections if the joint is long.
Remove the painter’s tape while the caulk is still wet, pulling it back at a 45 degree angle slowly and steadily. Removing tape after the caulk has dried tears the edges.
Wipe away any excess caulk from the tile or tub surface with a damp cloth before it dries.
Allow full cure time before using
Most silicone caulk requires 24 hours before water exposure and up to 72 hours for a full cure. Check the product label for the specific cure time. Using the tub or sink before the caulk has cured is one of the most common reasons a fresh caulk job fails.
Keep the bathroom ventilated during the cure period. Humidity slows curing and can affect the final result.
What causes caulk to fail prematurely
Applying over old caulk. The bond never holds properly and peeling starts within months.
Caulking over a damp surface. Moisture trapped under the caulk prevents adhesion and leads to mold growth behind the new bead.
Using the wrong product. Paintable latex caulk is not suitable for wet areas. Always use a product specifically rated for kitchen and bath with mold and mildew resistance.
Skipping the tape. Uneven edges and smeared caulk on tile surfaces are harder to clean up after the fact than preventing them with tape takes.
Not filling the tub before caulking. The joint gap changes with the weight of water and a caulk job done on an empty tub often cracks along the bottom edge after the first few uses.
