Clean mouldy bathroom or kitchen sealant safely, and replace it if the mould won't shift.
MS-01Open a window and get your kit readyOpen a window or door for ventilation, mould spores and cleaning fumes build up fast in a small bathroom. Put on rubber gloves and eye protection, some mould removers are strong enough to irritate skin and eyes. Lay down an old towel to catch drips.
MS-02Never mix cleaning chemicalsIf you use a bleach-based mould spray, don't mix it with any other cleaning product, especially anything containing ammonia. Mixing bleach with other chemicals can give off dangerous fumes. Use one product at a time and rinse the area before switching products.
MS-03Spray the mould and let it dwellSpray a specialist mould and mildew remover along the affected sealant. Leave it to work for the time stated on the bottle, usually 10-15 minutes, don't wipe it off straight away. This gives the chemical time to break down the mould staining, not just sit on top of it.
MS-04Scrub gently and rinseScrub the sealant line with a soft brush or old toothbrush, working along the bead rather than across it. Rinse thoroughly with clean water and wipe dry with a cloth. Check the result once it's dry, black staining that is just on the surface should lift out.
MS-05Decide if the sealant needs replacingIf black staining remains after cleaning and drying, the mould has grown into the silicone itself and cleaning won't fully remove it. This is normal after a couple of years in a wet room. The only proper fix is to strip out the old bead and re-seal.
MS-06Cut and peel out the old sealantRun a sealant removal tool or a sharp utility knife along both edges of the old bead, then peel it away by hand. Work slowly to avoid scratching the bath, tile or sink surface underneath. Pick out any leftover bits with tweezers or your fingernail.
MS-07Clean the gap and let it dry fullyWipe the empty gap with methylated spirit or a silicone-specific cleaner to remove any grease, soap scum or old adhesive residue. New silicone won't stick properly to a damp or greasy surface. Leave the area to dry completely, at least an hour, longer if the room is cold or steamy.
MS-08Mask off a neat lineStick masking tape along both sides of the gap, leaving a clean strip the same width as the old bead. This keeps the new line straight and stops silicone smearing onto the tile or bath surface. Take your time here, a good mask job is what makes the finish look neat.
MS-09Apply the new sealant beadChoose a sanitary-grade silicone with mould inhibitor, sold for bathrooms and kitchens. Cut the nozzle at an angle and load it into a sealant gun, then run a steady, even bead along the gap in one continuous pass. Smooth it immediately with a wet finger or a sealant smoothing tool.
1 tube · Sanitary-grade silicone sealant with mould inhibitor
MS-10Peel the tape and leave to curePeel off the masking tape straight away, while the silicone is still wet, pulling it away at an angle so you don't drag the bead. Don't touch, wipe or get the sealant wet for at least 24 hours, check the tube for the exact cure time. Keep the window open to help it dry.
MS-11Tidy upBin old sealant strips, used cloths and the empty tube. Wipe down the bath or sink area to remove any dust or spirit residue. Wash reusable tools in warm water before the silicone on them sets hard.
Some links may earn us a small commission at no extra cost to you.