How to Reseal a Bath With Silicone Properly
A clear, step-by-step guide to removing old sealant and applying fresh silicone around a bath, including prep, timing, masking and mistakes to avoid.
Resealing a bath is a job where the result depends almost entirely on preparation. Applying silicone is easy; getting it to stay watertight and look neat is a matter of removing the old sealant fully, drying the surfaces and timing the application. Here is a method that works.
Before you start
You will need:
- Sealant remover tool or a plastic scraper, and a craft knife
- Sanitary silicone, ideally anti-mould, in white or clear
- Sealant gun if the tube is a cartridge
- Masking tape
- Isopropyl alcohol or a suitable sealant-prep cleaner
- Cloths, a small bowl of soapy water or specialist smoothing tool
- Gloves and paper towels
Allow a day when the bath will not be used, as the silicone needs time to cure.
Step 1: Remove all the old sealant
Run a knife along the top and bottom of the old bead to cut it loose, then peel or scrape it away. Use a plastic tool on acrylic baths to avoid scratching. Remove every trace, including thin smears. New silicone sticks to clean surfaces, not old silicone.
If mould is embedded, it may have penetrated deeply. Clean with a mould remover or diluted bleach, rinse and allow it to dry thoroughly. If it keeps coming back, the cause may be ventilation; see how to deal with mould around sealant.
Step 2: Clean and dry
Wipe the gap and nearby surfaces with alcohol to remove soap film and grease. Leave the area to dry completely. A hairdryer on a low setting helps, but sealing over damp trapped moisture invites failure. Check the gap: if it is wider than about 5 mm, silicone alone may sag or split. A flexible filler strip or backing rod can help; if the bath is moving, it may need re-fixing.
Step 3: Fill the bath
This step is easy to skip and it matters. Fill the bath with water, or stand someone heavy in it, so the bath sits at its lowest position. If you seal it empty, the bath will drop when full and the seal will be stretched and tear.
Step 4: Mask the edges
Apply masking tape on the wall tiles and on the bath edge, leaving a gap of about 3 to 4 mm. This gives a clean, even line. Press the tape down well to avoid bleed.
Step 5: Apply the silicone
Cut the nozzle at 45 degrees to a size slightly narrower than the gap. Squeeze steadily along the gap, moving at an even pace, in one continuous bead if possible. Do it from one corner, and avoid stopping mid-run.
Step 6: Tool the bead
Within a few minutes, smooth the bead using a sealant tool or a finger dipped in soapy water. Press gently so the silicone makes contact with both surfaces and fills the joint. Wipe off excess.
Step 7: Remove the tape
Peel the masking tape slowly at an angle while the silicone is still wet. Do not wait until it skins over or you will drag the bead.
Step 8: Let it cure
Leave it for the time on the pack, typically 12 to 24 hours before water touches it. Then empty the bath carefully. Avoid showering over it during this period.
Common mistakes
- Sealing a damp surface
- Leaving old silicone behind
- Using general-purpose sealant in a wet area instead of sanitary silicone
- Filling too thick a bead, which looks bad and peels
- Sealing with an empty bath
- Using a bath in the cure period
When a reseal is not enough
If the bath keeps pulling away from the wall, the problem may be movement in the floor or an inadequately supported bath. If you see staining on the ceiling below or soft flooring, there may be a leak. In that case, stop and have it checked by a plumber or builder rather than applying more sealant over the top.
What it costs to have it done
A typical reseal costs around £60 to £120 for a bath, depending on region and condition. See cost to reseal a bath or shower in the UK for ranges and what affects them.
Getting help
If you would rather have someone do it, you can send a request on Compito with your postcode and a photo of the edge. You can message providers about the details, accept an offer and pay online, then leave a review once the booking is complete.
Frequently asked questions
Can I silicone over old silicone?
It is not recommended, as the new bead will not bond well and will fail quickly.
What colour silicone should I use?
White is usual with white baths and tiles; clear is useful with coloured surfaces or natural stone, though some stone needs a specific neutral-cure product.
How long does the sealant last?
It varies with product, preparation and ventilation. Good preparation and an anti-mould sealant help it last several years.