Strip out old, mouldy sealant and run a neat new bead around your basin to stop water getting behind it.
SB-01Clear the area and open a windowMove bottles, soap dishes and anything else off the basin edge. Open a window or door, because sealant remover and silicone both give off strong fumes in a small bathroom. Lay an old towel in the basin to catch scrapings.
SB-02Cut out the old sealantWearing gloves, run a sealant removal tool or a craft knife along both edges of the old bead, then peel it away in one strip where you can. Work slowly on tiled or acrylic surfaces so you don't scratch them.
SB-03Clean off every trace of old residueWipe the joint with methylated spirits or a proper silicone remover on a cloth. Scrub away any black mould, soap scum or leftover silicone film — new sealant will not stick to any of it.
SB-04Let the joint dry fullyLeave the area to dry completely — a few hours in a warm room, longer if it's been damp. Sealant applied over a wet joint will fail early and let water back in behind it.
SB-05Mask both sides of the gapRun low-tack masking tape along the basin edge and the wall or worktop, leaving an even gap between the two strips for the new bead. This gives you a crisp, straight line without needing a steady hand.
SB-06Load the gun and prepare the sealantUse a bathroom-grade anti-mould silicone sealant, not a general-purpose one. Cut the nozzle tip at a 45° angle to match the width of your gap, pierce the inner seal, and load the tube into a skeleton gun.
SB-07Run a steady bead along the jointHold the gun at a consistent angle and squeeze steadily, moving in one continuous pass rather than stopping and starting. Slightly overfill the gap — you'll smooth off the excess in the next step.
SB-08Smooth the bead into a neat curveDip a finger or a plastic smoothing tool in soapy water and run it along the bead in one single, confident motion. Don't go back over it a second time or you'll drag it out of shape.
SB-09Peel off the masking tape straight awayWhile the sealant is still wet, lift the tape away at a shallow angle before a skin forms. This leaves a sharp, professional edge instead of pulling the bead about.
SB-10Leave it to cure before useCheck the tube for the exact cure time, but allow at least 24 hours before running water near the joint or touching it. Keep the window open a little to help it cure evenly.
SB-11Tidy upBin the old sealant strips, used tape and cloths. Wipe down the gun nozzle and basin, and put your tools away ready for next time.
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