Silicone sealant around baths, showers, sinks, and worktops looks great when it’s new. Give it a few years and it turns yellow, grows mould, peels away from surfaces, and generally looks terrible. Replacing it is one of the quickest, cheapest ways to make a bathroom or kitchen look significantly better — but getting a clean, professional finish requires the right technique.
When to Replace Silicone Sealant
- Black mould that won’t come off with cleaning — it’s growing inside the silicone, not on the surface
- The sealant is peeling away from one or both surfaces
- It’s gone yellow or discoloured
- There are gaps or cracks in the bead
- Water is getting behind the sealant — you might notice damp patches or loose tiles
What You’ll Need
- Stanley knife or silicone removal tool
- Silicone sealant remover (UniBond, Everbuild, or similar)
- New silicone sealant — always use a kitchen/bathroom anti-mould formula
- Skeleton gun (caulk gun)
- Masking tape
- Spray bottle of soapy water (washing-up liquid and water)
- Disposable gloves
- Clean cloths and white spirit
Step-by-Step: Removing Old Silicone
Step 1: Score the Edges
Run a sharp Stanley knife along both edges of the old silicone bead — where it meets the tile/wall on one side and the bath/worktop on the other. This breaks the bond and makes removal much easier. Be careful not to scratch tiles or acrylic baths.
Step 2: Peel Off the Bulk
Starting at one end, grip the silicone and pull. If you’ve scored the edges properly, it should come away in strips. A dedicated silicone removal tool (£3–£5 from any hardware shop) works better than a knife for this step as it gets behind the sealant without scratching surfaces.
Step 3: Remove the Residue
There will always be a thin film of silicone left behind. Apply a silicone sealant remover gel to the residue, leave it for the time stated on the product (usually 2–4 hours), then scrape off the softened residue with a plastic scraper. Repeat if necessary. Everbuild Sealant Remover is widely available and effective.
Step 4: Clean and Dry
Wipe the joint with white spirit on a clean cloth to remove any remaining film, then let it dry completely. New silicone won’t bond to a damp or contaminated surface — this prep step is what separates professional results from DIY botch jobs.
Choosing the Right Silicone
| Type | Best For | Anti-Mould? | Price |
|---|---|---|---|
| Standard silicone | General purpose, non-wet areas | No | £3–£5 |
| Kitchen & bathroom silicone | Wet areas — baths, showers, sinks | Yes (built-in fungicide) | £4–£7 |
| Sanitary silicone | Professional-grade wet areas | Yes (enhanced) | £6–£10 |
| Neutral cure silicone | Natural stone, marble, mirrors | Varies | £5–£8 |
| Acetoxy silicone | Glass, glazed tiles, PVC | Varies | £3–£6 |
For bathrooms and kitchens, always use a silicone specifically labelled as kitchen and bathroom or sanitary grade with built-in anti-mould properties. Standard silicone in a wet environment will grow mould within months. Spend the extra £2 — it’s worth it.
Step-by-Step: Applying New Silicone
The Masking Tape Method (Recommended)
This is the technique that professionals use to get perfectly straight, even beads:
- Apply masking tape — run two strips of masking tape parallel to the joint, one on each side, leaving a gap the width of the bead you want (typically 5–8mm). Press the tape down firmly so sealant can’t creep underneath
- Cut the nozzle — cut the silicone cartridge nozzle at a 45-degree angle. Cut it small — you can always cut more off, but you can’t add material back. The opening should be roughly the width of your desired bead
- Apply the silicone — load the cartridge into a skeleton gun and apply a steady, continuous bead along the joint. Keep the gun moving at a consistent speed. Apply slightly more than you think you need — you’ll tool it smooth in the next step
- Tool the bead — spray your finger with soapy water (or use a silicone finishing tool) and run it smoothly along the bead in one continuous stroke. The soapy water prevents the silicone from sticking to your finger. Apply gentle, even pressure
- Remove the tape immediately — pull the tape away while the silicone is still wet, pulling at a 45-degree angle away from the bead. If you wait until the silicone skins over, the tape will tear the bead. This step must be done within 2–3 minutes of application
Common Mistakes
- Applying over old silicone — new silicone doesn’t bond to old silicone. It will peel off. Remove the old stuff completely
- Not using the masking tape method — freehand application looks messy. Always tape
- Cutting the nozzle too big — start small. A big nozzle opening makes a fat, uneven bead that’s hard to tool
- Using standard silicone in wet areas — mould will grow inside it within a few months
- Not filling the bath first — when sealing around a bath, fill it with water before applying silicone. The weight of the water pulls the bath down to its lowest point. If you seal with an empty bath, the sealant stretches and can pull away when the bath is next filled
- Disturbing the bead — once tooled, don’t touch it. Leave it for 24 hours to cure fully
How Long Does Silicone Take to Cure?
Most bathroom silicones are touch-dry within 30 minutes but take 24 hours to fully cure. Don’t use the bath, shower, or sink during this curing period. In cold weather, curing takes longer — avoid applying silicone in rooms below 5°C. The UniBond sealant range includes products with faster cure times if you need to use the bathroom sooner.
Keeping Silicone Mould-Free
Even anti-mould silicone eventually develops mould if conditions are right. To extend its life:
- Ventilate the bathroom — open a window or run the extractor fan during and after showers
- Wipe down sealant after showers to remove standing water
- Spray weekly with a bathroom cleaner that contains bleach or anti-mould agents
- Address the root cause if mould appears quickly — poor ventilation is the usual culprit
