Find the Right Sealant for Your Bathroom or Kitchen
Choosing the wrong sealant leads to cracking, mould, and leaks. Use this guide to find the right product for your surface, situation, and skill level.
Step 1: What Surface Are You Sealing?
- Bath, shower tray, or basin edge – You need a sanitary silicone sealant that flexes with the bath and resists constant water exposure. Our top pick: UniBond Anti-Mould Kitchen & Bathroom Sealant – White.
- Around tiles or grout lines – Use a flexible silicone or hybrid sealant rather than rigid grout, which cracks under movement.
- Kitchen sink or worktop join – A kitchen-grade sanitary sealant works here too. The UniBond product above is rated for both kitchen and bathroom use.
- Outdoor or UPVC window frames – Use a dedicated exterior or frame sealant instead of a bathroom product.
Step 2: Do You Need Mould Resistance?
For bathrooms and kitchens, always choose a sealant with anti-mould (fungicide) protection. Standard silicone will grow black mould within weeks in a humid environment. Look for wording such as "anti-mould", "mould-resistant", or "with Microban®" on the packaging.
The UniBond Anti-Mould Sealant contains built-in anti-mould technology and is backed by a 5-year performance guarantee.
Step 3: When to Remove Old Sealant Instead of Sealing Over It
Never apply new sealant over old. Layering traps moisture and causes the new sealant to fail quickly. Replace the sealant when you notice any of the following:
- Black mould that won't scrub off
- Cracking, peeling, or gaps pulling away from the surface
- A spongy or hollow feel when pressed
- Any visible water ingress behind tiles or walls
As a rule of thumb, bathroom sealant should be replaced every 5–10 years, or sooner if you spot the signs above.
Step 4: Removing Old Sealant
- Score along both edges of the old sealant with a Stanley knife or dedicated sealant removal tool.
- Pull the old sealant away in strips – it usually comes off in one piece if it has fully cured.
- Use a silicone remover spray or gel for any stubborn residue. Leave for the time stated on the product, then scrape off.
- Clean the surface thoroughly with an isopropyl alcohol wipe or methylated spirits. Any grease or old silicone residue will prevent the new sealant from bonding.
- Allow the surface to dry completely before applying new sealant – a hair dryer on low can speed this up.
Step 5: Applying New Sealant
- Fill the bath with water before you start. This stretches the bath to its heaviest load, so the sealant cures with the gap at its widest. If you seal an empty bath, the sealant may crack when the bath is in use.
- Cut the nozzle at a 45° angle. Start with a small hole – you can always cut more off, but you can't put it back.
- Apply a continuous, even bead in a single pass. Move at a steady pace – too slow and you get a thick blob, too fast and the bead is too thin.
- Do not stop and restart mid-run if you can avoid it – joins are a weak point.
Step 6: Smoothing the Sealant
Smoothing gives a professional finish and presses the sealant into the joint for a better bond. Do this within 5–10 minutes of application, before a skin forms.
- Sealant finishing tool – The easiest option; gives a consistent concave finish.
- Wet finger – Dip your finger in a mix of washing-up liquid and water, then run it along the bead in one smooth stroke. The soap stops the silicone sticking to your skin.
- Avoid going back over the same area twice – it lifts the sealant and creates unevenness.
- Remove any masking tape immediately after smoothing, before the sealant skins.
Step 7: Drying and Curing Times
| Stage | Timing |
|---|---|
| Skin forms (touch-dry) | 30–60 minutes |
| Safe for light water contact | 24 hours |
| Fully cured (shower/bath use) | 24–48 hours |
Times vary by brand and conditions. Always check the product label. Keep the room ventilated during curing – good airflow speeds the process. Drain the bath after the sealant is fully cured.
Recommended Product
UniBond Anti-Mould Kitchen & Bathroom Sealant – White
Ideal for baths, showers, basins, and kitchen sinks. Flexible, waterproof, and anti-mould with a 5-year guarantee. Easy to apply straight from a standard sealant gun.
