How to Remove and Replace Mouldy Silicone Easily, by The DIY Guy on YouTube. 9 min 49 s.
- Video length
- 9 min 49 s
- Time to do it
- 1 hour plus 24 hours curing
- Difficulty
- Medium
- Steps
- 8
What you need
Steps
Run a silicone removal tool or a sharp knife along both edges of the old bead. Keep the blade angled away from your fingers and pull the strip out in one piece where you can.
Scrape off the leftover slivers with a plastic scraper, then wipe the joint with white spirit or silicone remover to clear grease and residue.
Dry the joint completely with a cloth and let it air dry. Silicone will not stick to a damp or dusty surface.
Run masking tape along both sides of the joint, about 5mm out from the corner, so the new bead has straight edges.
Drop the tube into the gun, cut the nozzle at 45 degrees to roughly 5mm and pierce the inner seal with the pin on the gun.
Push the gun steadily along the joint, keeping the nozzle in contact with the surface so the silicone fills the gap in one continuous bead.
Smooth the bead with a profiling tool or a wet finger, then peel the tape off straight away while the silicone is still wet.
Leave the bead to skin over, then keep the area dry for 24 hours before the bath or shower is used again.
Tips and common mistakes
Use a sanitary grade silicone labelled mould resistant, since standard sealant blackens again within months in a wet room.
Fill the bath with water before you apply the bead, then drain it after curing, so the weight of the bath does not stretch and split the seal.
Never spread new silicone over old sealant, because it will lift and leak within weeks.
Open a window when using white spirit or silicone remover, and wear gloves if you have sensitive skin.
Questions
Do I have to remove every bit of the old silicone?
Yes. New silicone will not bond to old sealant, so scrape until you reach clean tile, glass or tray. Small slivers left in the corner will cause the new bead to peel.
How long before I can use the bath or shower?
Most sanitary silicones skin over in 10 to 20 minutes but need 24 hours to cure fully. Keep the area dry and avoid water spray for that whole period.
What is the best way to get a neat, smooth line?
Masking tape on both sides gives you a straight edge. Smooth the bead in one pass with a profiling tool, then pull the tape before the silicone starts to set.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
