Strip out old, mouldy silicone completely using a knife and remover, then clean and dry the joint ready for fresh sealant.
RS-01Ventilate the room and gather your toolsOpen a window or door — sealant remover gives off strong fumes. Lay an old towel in the bath or on the worktop to catch scraps. Put on disposable gloves before you start, as old silicone and mould can be unpleasant to handle.
RS-02Cut along both edges of the old beadRun a utility knife along each side of the silicone line, keeping the blade flat against the tile or bath so you don't gouge the surface. Then cut a line down the middle of the bead. This breaks the seal into strips you can peel away by hand.
RS-03Peel away the loosened siliconePull the cut strips away by hand or with a plastic scraper, working slowly so it comes off in one piece where possible. Use the scraper's corner to lift stubborn bits at the ends of the run. Don't use a metal scraper on an acrylic bath or shower tray — it will scratch.
RS-04Strip stubborn residue with a silicone removerApply a proprietary silicone and mastic remover gel to any leftover residue and thin film. Leave it for the time stated on the bottle, usually 15-30 minutes, then scrape off with the plastic scraper. Repeat on any patches that don't lift first time.
RS-05Clean the joint with white spirit or isopropyl alcoholWipe the whole channel with a lint-free cloth dampened with white spirit or isopropyl alcohol. This lifts any grease, soap scum and remaining residue so new sealant can bond properly later. Wipe again with a dry cloth to finish.
RS-06Treat any black mould stainingIf the grout or tile edge is stained black, spray on a mould remover and leave it for the time on the label before rinsing off. Some staining in porous grout may not fully lift — that's normal and won't stop new sealant working.
RS-07Dry and inspect the jointDry the whole channel thoroughly with a clean cloth, then leave it uncovered for an hour or two so any damp trapped behind the old sealant can evaporate. Check for cracked grout or a gap behind the old sealant line — these can point to a slow leak, so look before you reseal, not after.
RS-08Mask the edges ready for new sealantRun masking tape along both sides of the gap, keeping an even width all the way along. This gives you a crisp, straight line when you apply fresh silicone and stops smears on the tile or bath.
RS-09Clear up and air the roomBin the old silicone strips and used cloths — don't put solvent-soaked cloths straight in an enclosed bin. Wash your hands and any tools with warm soapy water. Leave the window open until any remover fumes have cleared.
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