Guide
Can you reseal a bath or shower without removing the old silicone?
No. Not in any way that lasts, and the reason is worth two minutes because it explains almost every failed reseal anybody has ever paid for.
It is a reasonable question. Running a fresh bead over a tired one looks like it should work, it takes twenty minutes, and on the day it is finished it looks perfect. It is also the single most common thing done to a bath joint, which is why so many baths have three layers of silicone on them and a black line at the tap end.
Silicone does not bond to cured silicone
Fresh silicone bonds well to glass, glazed ceramic, acrylic, stone and steel, which is why a joint works at all. It does not bond to silicone that has already cured. It sits against it, it takes the shape of it, and it holds on with very little grip.
That means a new bead is only as well attached as the old bead underneath it. If the old one is lifting at one corner, the new one comes away with it, usually in one long piece, and usually about six months later when whoever did it is not around.
This is also why a joint that has been sealed three times is harder to put right than one that has never been touched. There is more to take off, and each layer has to come off separately.
The mould is inside the material, not on it
Black spotting in an old joint is not dirt on the surface. It is mould that has grown into the silicone, feeding on soap residue and the moisture the joint has been holding. That is why bleach whitens it for a week or two and then it comes back, and why scrubbing does nothing.
Seal over that and you have put a clear layer of new material over a living colony with a moisture supply. It does not stop; it carries on, and within a few months it shows through the new bead as a grey shadow, then as spots.
There is no product that fixes this from above. The material with the mould in it has to leave the room.
The part nobody mentions: the residue film
Even when somebody does take the old joint off properly with a blade, there is a film left behind on the tile and the bath. It is a fraction of a millimetre thick, you can barely see it, and you can definitely feel it if you run a fingernail along the edge.
New silicone applied onto that film bonds to the film. The film is loosely attached to the tile. So the joint fails early, for the same reason as before, and this time nothing looked wrong on the day at all.
The film comes off with a purpose made silicone remover left on for a few minutes and then wiped away, followed by a solvent wipe. It takes ten minutes and it is the difference between a reseal that lasts and one that does not.
If you are doing it yourself
It is a job worth having a go at, and the two things that catch people out are both above. Take every layer off, then treat the residue rather than assuming a scraped tile is a clean tile.
After that: let the joint dry properly, and give it longer than feels necessary. A joint that has been holding water for a year is wetter than it looks. Mask both sides, run the bead in one continuous pass, tool it once with a wet finger or a spatula, and pull the tape immediately while the silicone is still wet. Tape pulled after it has skinned will drag the edge off with it.
Then leave it alone for a full day. That last part is free and it is the one most people get wrong.
Also asked
Related questions
What about the sealant strip that sticks over the top?
Self adhesive sealant strip works for about a season. Underneath it the joint is whatever it was before, and the strip itself holds water against the tile along its whole length. It comes off in one piece later on, usually with something unpleasant behind it.
Can I paint over mouldy sealant?
No. Nothing adheres to silicone reliably, paint least of all, and the mould is inside the material anyway. There is no coating that turns a failed joint into a good one.
If you would rather not
The job this article describes, done for a published price
The pages this covers
- Silicone removal and replacement
The full strip out: mouldy, lifting or badly applied sealant taken out completely, the joint cleaned back to bare surfaces, and a new bead run properly.
- Bath resealing
The old sealant round the bath stripped out completely, the joint cleaned back and dried, and a fresh sanitary bead run and tooled. £95 including VAT and silicone.
The other guides
- Why does bathroom sealant go mouldy, and can it be stopped?
It grows inside the silicone, feeding on soap residue in a joint that never fully dries. What actually slows it down, and what makes no difference.
- How long does silicone take to dry, and when can you use the bath?
Touch dry in under an hour, usable after twenty four. Why those are two different numbers, and what happens if you do not wait.
- Why does bathroom sealant leak, and is the sealant even the problem?
Water on the floor below a bathroom has three usual causes and only one of them is the sealant. Here is how to tell which one you have before you pay for the wrong repair.
- Which silicone should go in a bathroom, and does the type matter?
Sanitary grade, not general purpose. Acetoxy on tile and acrylic, neutral cure on stone and metal. White or clear is a choice, and everything else on the shelf is a distraction.
- How often should bathroom sealant be replaced?
There is no fixed interval. There are four signs, and a family bathroom gets through a joint considerably faster than a spare one does.
Get a price
Book a reseal with Exeter Silicone Services
Send a photograph of the joint and say which fittings need doing. Back comes the price off the published card and the next free slot. Ringing is quicker if you want a date fixed today.
- Bath or shower
- £95
- Both on one visit
- £150
- Whole bathroom
- £185
VAT and silicone included. Minimum charge £95.