How To Remove Bathroom Sealant
Mouldy silicone around a bath or basin comes out cleanly with a sharp blade and the right remover.
The short answer
To remove bathroom sealant, soften the old silicone with a sealant remover gel, then run a sharp utility knife along both edges of the bead to break its grip. Pull the sealant away by hand or with a remover tool, rub off the last traces with white spirit and kill any mould underneath before the joint is dry enough for new sealant.
Silicone sealant around a bath, shower tray, basin or worktop doesn't last forever. After a few years it discolours, peels away at the ends or turns black with mould that no amount of cleaning will shift. The featured photo shows a typical example, with black mould running along the bead at the edge of a bath.
Taking out old sealant is one of the easier bathroom jobs, but it comes as a pair. Once the old bead is out, the joint isn't watertight until a new one goes in and cures, so plan the job for a time when the bath or shower can sit unused.
Tools For Removing And Renewing Sealant
- Sealant remover gel or WD-40 (optional)
- A Stanley knife or utility knife with a fresh blade
- A sealant remover and smoothing tool
- White spirit and a cloth
- Mould remover spray
- New bathroom sealant
- A sealant gun
How To Remove Bathroom Sealant
1. Soften The Old Sealant
This step is optional, but it makes the rest of the job easier on old, stubborn silicone. Rub a sealant remover gel into the bead or give it a spray of WD-40, then leave it for a few minutes to soften.
2. Cut Through The Sealant
Run a sharp Stanley knife along the edge of the bead where it meets the wall, then along the edge where it meets the bath. That breaks the bond on both sides, as you can see in the photo below.
Keep the blade low and almost flat to the surface. On an acrylic bath or shower tray, a plastic remover tool is the safer choice, as a steel blade can scratch the finish.
3. Pull The Sealant Away
Once the bead is cut free, grab one end and peel it away. Fresh cuts let long strips come away in one go. When it breaks off in small pieces, switch to a remover tool and scrape the rest out of the joint.
4. Clear Every Last Trace
New sealant won't stick properly to old sealant, so check the joint closely before moving on. Rub stubborn smears with a cloth and white spirit to lift the sticky film. Any pieces that have dropped down into the gap can be pulled out with tweezers or long nose pliers.
5. Treat The Mould
Mould grows underneath old sealant, and it'll come straight back through the new bead if you leave it there. Spray the joint generously with a proper bathroom mould remover, leave it for the time on the label, then rinse and let it dry fully. Our guide on treating black mould at the source goes further if it's spread beyond the joint.
Running A Fresh Bead Of Sealant
The joint needs to be completely dry and free of dust, mould and old silicone before you reseal. Pick a sealant made for bathrooms with a mould inhibitor, and our roundup of the best bathroom sealants covers the ones we rate. Then work through the bead in one go:
- Check the surfaces are clean and bone dry.
- Cut the nozzle at an angle to suit the width of the gap and load the cartridge into the gun.
- Start at one end and run the bead to the other without stopping.
- Keep the pressure on the trigger and the speed along the joint steady so the bead stays even.
- Smooth it straight away with a sealant tool or a wet finger.
For baths, fill the bath with water before you seal. The weight pulls the bath down to its lowest point, so the sealant isn't stretched and split the first time someone gets in. Our step by step guide to sealing a bath properly has photos of every stage, and the same method works around a shower tray.
Why A Proper Removal Tool Is Worth Having
You can get old sealant out with nothing more than a knife and your fingernails, but a cheap remover tool and a softening gel speed the job up and cut the risk of scratching the bath or chipping a tile. A damaged acrylic bath costs far more to put right than the tool does.
Taking out the old bead is also the first stage of other bathroom jobs, such as fitting a new shower screen, and once the joints are clear it's a good moment for a deep clean of the tiles and grout before the fresh sealant goes in.
Watch Us Do It
Sealing Bath, Shower & Other Fittings Is Much Easier With A Quality Sealant & We've Tested Multiple!
What People Also Ask Us
What dissolves silicone sealant?
Nothing fully dissolves cured silicone sealant at home, but a sealant remover gel softens it enough to cut and peel away easily. WD-40 and white spirit also loosen the bond and lift the sticky film left behind. The bulk of the bead still needs cutting out with a knife or remover tool first, with the softener used for the last traces.
Can you put new sealant over old sealant?
New silicone sealant won't bond to old silicone, so putting a fresh bead over the top soon leads to peeling and leaks. Mould under the old bead also grows back through the new one. Remove the old sealant completely, clean off any residue with white spirit, treat the mould and let the joint dry before resealing.
How long after removing sealant can you reseal?
You can reseal as soon as the joint is completely dry and clean. If you've used mould remover, rinsed the area or used white spirit, give it time to dry out fully in a well ventilated room, and leaving it overnight is the safe option. Sealing over a damp joint stops the new sealant bonding properly and traps moisture behind it.
Why does bathroom sealant go black?
Bathroom sealant goes black because mould grows on and underneath it in the warm, damp conditions around a bath or shower. Poor ventilation and water left sitting on the bead speed it up. Once the mould has grown into the silicone it can't be cleaned out, so the sealant needs removing and replacing with a mould resistant one.
Can I use a Stanley knife on an acrylic bath?
Swap to a plastic remover tool. A steel blade can scratch acrylic, and putting right a scratched bath costs far more than the tool. Elsewhere, a knife held low and almost flat, run along both edges of the bead, does the job.
Do I need a sealant remover gel to take out old silicone?
No, it's optional. A knife and your fingernails will get the bead out, but the gel softens stubborn old silicone that would otherwise come away in crumbs. Pair it with a cheap remover tool and you're less likely to scratch the bath or chip a tile too.
Why fill the bath with water before resealing?
So the sealant goes on with the bath already sitting at its lowest point. Seal it empty and the bead gets stretched and split the first time someone climbs in. Run the bead in one steady pass, smooth it straight away, and use the same trick around a shower tray.
What's the best way to stop mould coming back under new sealant?
Kill it before you reseal. Mould left in the joint grows straight back through a new bead, so give it a good spray of bathroom mould remover, leave it for the time on the label, then rinse and let it dry right out. Finishing with a sealant that has a mould inhibitor helps keep it away.
Richard has spent years renovating properties and turning them into rentals and Airbnbs. Like a lot of people he started out as a beginner, and these days there isn't much DIY he won't take on.