Apply silicone sealant cleanly
20–30 mins — the finish that makes a bathroom look professional
A clean silicone bead is the difference between a bathroom that looks finished and one that looks amateur. The technique is simple — tape, a consistent bead, one tooling pass, tape off while wet.
Last updated: March 2026
Only basic tools needed — most homes already have them.
Part of the Bathroom Renovation project
Silicone sealing is the finishing step in Phase 5: Finishing of a full bathroom renovation — the last thing you do before the room is complete.
If you're renovating your bathroom, start here →Before you start
This guide covers applying fresh silicone sealant to a bath, basin, shower tray, or tiled joint. If you are replacing existing sealant, remove the old sealant completely first — see our Remove silicone sealant guide.
Use a bathroom-grade silicone sealant with fungicide — these are formulated to resist mould in wet environments. Standard silicone (sold for windows or general use) will go black with mould within months in a bathroom.
Do not use the bath or shower for at least 24 hours after applying — silicone needs time to cure before contact with water.
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Tools & materials
- ✓Masking tape— run along both sides of the joint for a clean edge
- ✓Sealant gun (cartridge gun)— for applying the sealant from the tube
- ✓Scissors or craft knife— to cut the nozzle at 45 degrees
- !Bathroom silicone sealant (with fungicide)— match the colour to your grout — white, grey, and magnolia are most common
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Prepare the surface — clean and completely dry
The joint must be free of old sealant, soap residue, grease, and moisture before you start. Wipe both surfaces with a clean cloth dampened with white spirit or isopropyl alcohol, then wipe dry. Allow at least 30 minutes for the surfaces to fully dry — longer in a cold bathroom. Why: silicone will not adhere to a damp, greasy, or contaminated surface. A bead applied to a surface with any moisture or residue will look fine for a few weeks, then start peeling away at the edges. The preparation is what makes the difference between sealant that lasts three years and sealant that peels within months.
Most people get this done in under 5 minutes.
Where beginners go wrong
Applying to a damp or dirty surface. The sealant will look fine initially but peel away from the surface within weeks. Dry, clean, grease-free surfaces are non-negotiable.
Cutting the nozzle too wide. A large opening deposits too much sealant — it overflows the tape, sags, and is impossible to tool smooth. Cut smaller than you think you need.
Tooling back over sections already done. Each pass of your finger drags sealant out of the joint. One smooth pass is correct. If the bead needs adjustment, it must be done in one movement.
Leaving the tape on until the sealant cures. Removing tape after curing tears through the bead and leaves a ragged edge. Remove it immediately after tooling, while the sealant is still wet.
Worth knowing
Bathroom sealant that goes black with mould within a few months is almost always a ventilation problem — the room needs an extractor fan running during and after showers
Silicone cannot be painted over — if you need a coloured finish, use a decorator's caulk (acrylic-based) instead, which is paintable but less waterproof
A gap that keeps opening up at the same point (typically between a bath panel and the wall) usually means the bath is moving — fix the bath first, or the sealant will crack again
Recommended starter kit
Five tools that cover most home repairs.
- →Adjustable spannerAmazon·Screwfix
- →Screwdriver setAmazon·Screwfix
- →PTFE tapeAmazon·Screwfix
- →Spirit levelAmazon·Screwfix
- →Tape measureAmazon·Screwfix
Want everything in one go? Get it on Amazon
What you just learned
You know how to apply silicone sealant with a clean professional finish — tape, consistent bead, one tooling pass, tape off while wet. This skill is used in every bathroom and kitchen job. Once you have done it once, it is quick and reliable.
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⚠️ Watch out if you rent
Resealing a bath, basin, or shower in a rented property is generally considered maintenance and does not require landlord permission. If the sealant has failed due to a structural crack or movement in the floor, that is a landlord responsibility — report it in writing.