Best Bathroom Sealant UK 2026: Anti-Mould Silicone for Showers, Baths and Sinks

Quick Comparison: Best Bathroom Sealants and Tools UK 2026

Best Bathroom Sealants UK 2026: Full Reviews

1. Dow Corning 785+ Bacteria Resistant Sanitary Silicone — Best Professional-Grade Bathroom Sealant

→ View on Amazon (approx. £8–12 per 310ml)

Dow Corning 785+ is the professional standard for sanitary silicone sealant in the UK. Based on UK customer reviews and product specifications, it is the product most frequently used by bathroom fitters, plumbers, and tiling contractors when quality is the priority rather than price. It complies with BS 5889 Type A — the British Standard for sanitary silicone — and incorporates anti-bacterial technology that actively resists the growth of mould and bacteria in the joint.

The "25 year" longevity claim is not marketing hyperbole in the right conditions: properly applied to a prepared joint in a well-ventilated bathroom, Dow Corning 785+ lasts significantly longer than budget alternatives. It is available in white, translucent, and a range of standard bathroom colours, and it cures to a glass-smooth finish that is easy to keep clean.

The 310ml cartridge requires a standard skeleton caulking gun to apply. The product is straightforward to work with — it tools well and does not skin too quickly, which gives you time to smooth the bead before it sets. For a shower enclosure, bath surround, or basin-to-tile joint that needs to last, this is the right product.

Pros:

• BS 5889 Type A compliant — the British Standard for sanitary silicone
• Anti-bacterial technology inhibits mould growth
• Long lifespan when applied correctly
• Glass-smooth finish — easy to maintain
• Available in white, clear, and multiple bathroom colours
• Trusted by UK bathroom fitters and tiling contractors

Cons:

• Requires a caulking gun — not ideal if you don't have one
• Slightly higher price than consumer products
• Not paintable — silicone does not bond with paint

Best for: Any new bathroom installation or full reseal where longevity and mould resistance are the priority. The right choice for shower enclosures, bath surrounds, and basin joints.

2. UniBond Anti-Mould Sealant — Best Consumer Bathroom Sealant for Everyday Use

→ View on Amazon (approx. £6–8 per 300ml)

UniBond is the UK's most widely recognised consumer sealant brand and the Anti-Mould variant is their bathroom-specific formulation. Based on UK customer reviews and product specifications, it is the most accessible entry point for homeowners resealing a shower or bath without professional help. It comes in a nozzled cartridge that can be used with a caulking gun or the separate UniBond EasyFit nozzle system (which does not require a gun — the cartridge compresses by hand).

The anti-mould agents in UniBond's formulation are effective at inhibiting mould growth in typical UK bathroom conditions, where relative humidity during showering regularly exceeds 80%. The sealant is available in white, grey, and beige to match common bathroom colour schemes. It tools easily with a damp finger and has a forgiving working time for less experienced applicators.

For a homeowner who wants to reseal around a bath, sink, or shower tray themselves, UniBond Anti-Mould is the pragmatic choice: widely available (Screwfix, Wickes, B&Q, Amazon), reasonably priced, and reliable in normal bathroom conditions.

Pros:

• Widely available across UK DIY stores and online
• Anti-mould formulation for bathroom conditions
• Can be used without a caulking gun (EasyFit nozzle)
• Tools easily — forgiving for DIY applicators
• Available in multiple colours (white, grey, beige)
• Good value at ~£6–8

Cons:

• Not as durable as professional-grade silicone in heavy-use showers
• Mould resistance not as long-lasting as Dow Corning 785+
• Can skin quickly in warm conditions — work fast when smoothing

Best for: Homeowners resealing a bath, basin, or shower tray without professional help. The go-to consumer product for straightforward bathroom resealing.

3. Everbuild C3 500 Bath & Sanitary Silicone — Best Mid-Range Trade Sealant

→ View on Amazon (approx. £4–6 per 310ml)

Everbuild C3 500 sits between the consumer products and the premium professional options — it is a trade-spec sanitary silicone used by bathroom installers who need reliable performance at a competitive price. Per UK buyer reviews and published specifications, it offers good adhesion to ceramic tile, acrylic baths, steel sinks, and porcelain sanitaryware, and contains an anti-fungal additive that inhibits mould growth.

At £4–6 per 310ml cartridge, it is one of the most cost-effective ways to achieve a durable, anti-mould seal in a UK bathroom. The product is distributed through Everbuild's extensive UK trade network and is commonly found in independent builders' merchants. It is not as widely known to consumers as UniBond, but among bathroom fitters and tilers it is a familiar and trusted product.

Pros:

• Trade-spec quality at a competitive price
• Anti-fungal additive for mould resistance
• Good adhesion to tiles, acrylic, steel, and porcelain
• Everbuild is a major UK construction products brand
• Available in white and clear

Cons:

• Less widely available in consumer DIY stores than UniBond
• Requires a caulking gun
• Colour range is limited compared to some competitors

Best for: Bathroom fitters and confident DIYers wanting trade-quality results at a lower cost than premium brands. Solid everyday sanitary silicone for showers, baths, and basins.

4. Soudal Fix All Crystal — Best Hybrid Polymer for Clear Sealing

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Soudal Fix All Crystal is a hybrid polymer sealant — not silicone — that is crystal clear, paintable, and remains permanently flexible. From UK customer experience and manufacturer data, it is the product of choice where a truly invisible seal is needed: glass shower screens to tiles, clear basin surrounds, or anywhere the standard opaque white silicone bead would look out of place.

Hybrid polymers behave differently from silicone: they can be overpainted (a significant advantage for plastered bathroom areas that will be decorated), they do not shrink on curing, and they adhere to wet and damp surfaces. The crystal-clear formulation remains transparent after curing without the yellowing that affects some cheaper clear silicones over time.

For standard bath and shower sealing, a good anti-mould silicone remains the preferred choice. But for glass, frameless enclosures, or sealed areas that need to be painted, Fix All Crystal is the best available option.

Pros:

• Crystal clear — remains transparent without yellowing
• Paintable — can be overcoated after curing
• Adheres to wet and damp surfaces
• Permanently flexible, no shrinkage
• Suitable for glass, tile, acrylic, UPVC, and most bathroom materials

Cons:

• Higher price than standard silicone per cartridge
• Does not contain anti-mould agents — not ideal for heavy-use showers
• Requires a caulking gun

Best for: Glass shower screens, frameless enclosures, transparent sealing, and bathroom areas that will be painted. Not the primary choice for shower tray and bath sealing where anti-mould properties are needed.

Bathroom Sealant Tools: What You Need

5. Everbuild Sealant Smooth — Best Tool for a Clean Finish

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A clean sealant finish depends almost entirely on smoothing technique. While a damp finger works for simple applications, a profiling tool produces a consistently shaped concave bead that looks professional and is easier to keep clean than a flat or convex finish. The Everbuild Sealant Smooth includes multiple profile sizes to match different joint widths and is made from rigid plastic that glides through silicone without dragging. Drawing on real-world UK usage reports, it is one of the most used finishing tools in the UK trade for silicone work.

Best for: Producing a professional concave bead on bath, shower, and basin sealant joints. A small investment that significantly improves the finished result.

6. Sealant Removal Tool — Essential for Stripping Old Sealant

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Before applying any new sealant, all old sealant must be removed — this is the most important step in the entire process. A plastic sealant removal tool with a hooked blade allows you to cut and peel away old silicone from tile, acrylic, and enamel surfaces without scratching them. Trying to remove old sealant with a knife or chisel risks damaging the tile surface or acrylic bath. According to UK homeowner reviews, this tool is considered essential kit by professional bathroom fitters before any reseal job.

Best for: Removing old sealant without surface damage. Do not skip this step — applying over old sealant causes premature failure of the new application.

7. Skeleton Caulking Gun — Required for 310ml Cartridges

→ View on Amazon (approx. £5–10)

All 310ml silicone cartridges require a caulking gun. A basic skeleton gun — the open-frame type — is perfectly adequate for bathroom work. Look for one with a pressure-release trigger (pushes back on release to stop oozing), which makes it much easier to stop the sealant flow at the end of a bead. Based on product specifications and UK buyer feedback, even a budget skeleton gun does the job reliably for occasional home use.

Best for: Applying 310ml cartridge sealants. An essential tool if you don't already own one.

Silicone vs Acrylic vs Hybrid: Which Type Is Right for Your Bathroom?

Silicone Sealant

Silicone is the correct choice for all wet-area sealing in a bathroom — shower trays, bath surrounds, basin-to-tile joints, and around taps. It is fully waterproof when cured, flexible enough to accommodate the movement of an acrylic bath as it fills with water, and available with anti-mould and anti-bacterial additives. The downside is that silicone cannot be painted once cured, and surface preparation is critical — even slight contamination will cause adhesion failure.

Acrylic Caulk (Decorator's Caulk)

Acrylic caulk is water-based, easy to apply and tool, and paintable — making it the right choice for dry areas of a bathroom: skirting boards, coving, architraves, and gaps around window frames. It should not be used in shower enclosures or bath surrounds, as it is not genuinely waterproof and will crack and fail within months in a wet environment. Do not use acrylic caulk where silicone is needed.

Hybrid Polymer Sealants

Hybrid polymers like Soudal Fix All Crystal and CT1 combine properties of silicone and acrylic: they are permanently flexible like silicone, paintable like acrylic, and adhere to a wider range of surfaces than either. They are the specialist choice for glass, frameless enclosures, and areas that will be overpainted. They do not always contain anti-mould agents, so they are not the primary recommendation for shower tray and bath sealing, where mould resistance is the key requirement.

Step-by-Step: How to Reseal a Bathroom

Step 1: Remove All Old Sealant

Using a sealant removal tool, cut along both edges of the existing sealant bead and peel it away. For stubborn residue, apply a silicone remover solvent and allow 30 minutes before scraping. Remove every trace of old sealant — any remaining will prevent the new sealant bonding properly.

Step 2: Clean and Dry the Surface Thoroughly

Clean the joint area with isopropyl alcohol (methylated spirits works at a pinch) to remove soap residue, grease, and silicone remover. Allow to dry completely before applying new sealant. Silicone will not bond to a damp or contaminated surface. For acrylic baths, fill the bath with water before sealing — this puts the bath in its "loaded" position, and the sealant will not crack when the bath is filled in future use.

Step 3: Mask with Tape

Apply masking tape to both sides of the joint, leaving just the gap you want to fill exposed. This is the single most effective technique for achieving a clean, straight sealant line. Use low-tack decorator's tape to avoid lifting tile grout or damaging surfaces.

Step 4: Apply the Sealant

Cut the nozzle at 45° to match the joint width. Hold the gun at 45° to the joint and move steadily along it in a single pass, maintaining consistent pressure. Do not stop and start mid-joint if you can avoid it, as the overlaps are visible in the finished bead.

Step 5: Smooth the Bead

Using a finishing tool or a wet finger, smooth the bead in a single continuous pass immediately after application. The tool should press the sealant firmly into both surfaces to ensure adhesion. Remove any excess that squeezes out from under the tool. Work quickly — silicone begins to skin within 5–10 minutes.

Step 6: Remove the Tape and Allow to Cure

Pull the masking tape away immediately — before the silicone skins — at 45° to the joint to leave a clean edge. Allow the sealant to cure for at least 24 hours (preferably 48 hours) before exposing it to water. Keep the bathroom ventilated during cure time.

Common Mistakes When Sealing a Bathroom

• Applying over old sealant — the most common and costly mistake. New sealant over old creates a poor bond and will peel within weeks. Always strip the joint completely first.
• Not filling the bath before sealing — an empty acrylic bath sits higher than a filled one. Sealing on an empty bath creates a joint that opens every time the bath is used, leading to premature failure.
• Sealing on a damp surface — silicone will not bond reliably to a wet surface (unlike hybrid polymers). Allow the joint to dry completely before applying standard silicone.
• Using acrylic caulk in a wet area — acrylic is not waterproof and will fail in a shower or bath surround. Use silicone for all wet-area joints.
• Not masking the joint — attempting to cut a clean sealant line freehand consistently produces a ragged, unprofessional finish. Tape takes 2 minutes and makes a significant difference.
• Leaving the tape on too long — if you allow the silicone to start curing before removing the tape, you will tear the sealant bead. Remove tape immediately after smoothing.

When to Call a Professional

Resealing a bath or shower is a straightforward DIY task for most homeowners. There are situations, however, where professional involvement is the better choice:

• Persistent mould despite resealing — if black mould returns within weeks of a fresh seal, the problem may be inadequate ventilation, condensation on cold walls, or moisture behind tiles. A bathroom fitter or tiler can assess whether the waterproofing behind the tiles has failed.
• Tiles that are cracked or coming away from the wall — loose or cracked tiles in a shower enclosure indicate substrate moisture damage. This needs professional attention before resealing will be effective.
• Water appearing under the flooring — if you find damp under bathroom flooring adjacent to the bath or shower, this suggests the bath panel seal or the shower waste seal has failed. A plumber can inspect and repair these areas. See our plumber cost guide for 2026 pricing.
• Full bathroom renovation — for a full retile, new bath or shower tray installation, or bathroom layout changes, it is worth getting quotes from rated bathroom fitters. See our bathroom renovation cost guide for UK pricing.
• Mould that won't shift — if the grout and sealant are heavily discoloured beyond what mould remover can address, a professional reseal of the entire bathroom is the efficient solution. See our guide to the best mould removers for UK bathrooms for options before reaching for the phone.

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Frequently Asked Questions: Bathroom Sealant

How long does bathroom sealant take to dry?

Silicone bathroom sealants are typically touch-dry within 30–60 minutes and form a skin that resists water within 2–4 hours. However, full cure takes 24–72 hours depending on the product, temperature, and humidity. Do not use the shower or bath within 24 hours of applying new sealant — allow 48 hours if possible to ensure the sealant is fully waterproof before exposure to water.

Can you apply sealant over old sealant?

It is strongly recommended not to apply new sealant over old sealant. Old sealant should be fully removed before applying fresh product. Applying over existing sealant creates a poor bond, and the new sealant is likely to peel away within weeks rather than years. Use a sealant removal tool and sealant remover solvent to strip the joint completely before resealing.

What's the best anti-mould sealant for a shower?

Dow Corning 785+ Bacteria Resistant Sanitary Silicone is the professional standard for anti-mould shower sealant in the UK. For a widely available consumer option, UniBond Anti-Mould Sealant is reliable and found in most UK DIY stores. Both contain anti-fungal and anti-bacterial agents specifically designed to resist the humid conditions inside shower enclosures.

How often should you reseal a bathroom?

In a well-ventilated bathroom, quality silicone sealant should last 5–10 years before needing replacement. In a poorly ventilated bathroom or shower that sees heavy daily use, reseal every 3–5 years. The trigger to reseal is when you see persistent mould that cannot be removed, cracking or shrinkage in the sealant bead, or sealant pulling away from the tile or bath surface.

Is silicone or acrylic better for bathrooms?

Silicone is better for bathrooms in almost every case. It is waterproof, flexible, and mould-resistant. Acrylic (decorator's caulk) is paintable and easier to tool, but it is not truly waterproof and will fail in a shower or bath joint within months. Use silicone for all wet area sealing and reserve acrylic caulk for dry areas such as coving, skirting, and window frames.

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