The Best Bathroom Sealant 2021

To prevent the build-up of mould and mildew within a wet environment in your home, you will require a bathroom sealant. They contain fungicides to prevent the growth of bacteria and provide a waterproof seal in areas of high condensation.

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Best Bathroom Sealant
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Anti-mould sealants for a bathroom is an essential part of getting it ready for use without having issues later down the line. Unlike caulk, a bathroom sealant is waterproof, which protects walls and tiles from water damage.

Application of a bathroom sealant is commonly achieved by using a gun. However, there are alternatives that can be applied via a squeeze tube. The sealant used doesn’t last forever and it may require resealing every few years.

The best bathroom sealant is the UniBond Silicone, which is specifically designed for warm and humid environments.

Bathroom Sealant Comparison

Bathroom SealantColoursTube Size
UniBond Anti-MouldWhite or Ivory300 ml
Everflex 500White, Ivory or Clear295 ml
Dowsil 785 SanitaryWhite310 ml
Forever ClearWhite, Ivory, Grey or Clear80 or 310 ml
Gorilla Glue Multi-UseClear80 ml
151 SiliconeClear50 ml

Areas that require sealing in the bathroom include tiles, shower trays, cubical doors, baths, sanitary fittings and much more. There are a range of sealants available but for rooms with high condensation, it’s vital that it is water resistant and includes fungicides to prevent bacteria build-up.

Below is a list of the best bathroom sealants that are easy to apply, water resistant and prevent the build-up of mould or mildew.

The Best Bathroom Sealant

1. UniBond Bathroom Silicone Sealant

UniBond Bathroom Silicone SealantOne of the most popular bathroom sealants in the UK is by the UniBond brand. It has been specifically designed for warm and humid environments and is perfect for use in bathrooms and shower rooms.

The UniBond formula forms a permanently flexible, waterproof and mould resistant sealant that’s suitable for tiled areas, bathrooms, kitchens and worktops.

Other features of the UniBond Bathroom Silicone Sealant include:

  • Long lasting with high adhesion
  • Touch dry in 20 minutes
  • Fully dry in 24 hours
  • Available in white or ivory
  • 300 ml tube with resealable cap
  • Can be cleaned with any soap

Although expensive, it’s the best bathroom silicone sealant that’s designed specifically for warm and humid environments. The anti-mould formula is easy to use with a sealant gun and it provides a long lasting finish in the colour of your choice.
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2. Everflex 500 Bath & Sanitary Silicone

Everflex 500 Bath & Sanitary Silicone
Another popular bathroom sealant is the Everflex 500, which provides a waterproof seal and is certified under the harmonized European standard (EN15651).

In terms of its usage, it’s an anti-fungal formula designed for sealing baths, showers, sanitary fittings and tiles.

Other features of the Everflex 500 Silicone include:

  • Available in clear, white or ivory
  • Permanently flexible
  • Fast curing formula
  • 295 ml tube
  • Designed to prevent mold build-up

This bathroom sealant is suitable for commercial and domestic applications and is a great alternative to the UniBond above. One drawback is that it doesn’t have the resealable cap but it does have the benefit of being much cheaper.
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3. Dow Corning Dowsil Bathroom Sealant

Dow Corning Dowsil Bathroom Sealant
The Dowsil bathroom sealant by Dow Corning is a popular option that focuses upon resisting bacteria and mould. The formula conforms to ISO 22196:2007 and ISO 11600-F-20LM industry standards and is suitable for both domestic and commercial applications.

Other features of the Dow Corning Dowsil include:

  • Fast curing and tack free in just one hour
  • Formula includes a fungicide to resist mould
  • Can be used in bathrooms, kitchens and sanitary fittings
  • Only available in white
  • 310 mm tube

The Dowsil formula is an excellent all-round bathroom sealant that’s developed by the reputable Dow Corning brand. They have even gone as far as testing this product against bacteria growth, MRSA, E. Coli and Salmonella. Overall, the Dow Corning Dowsil offers great value for money and it won’t disappoint.
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4. Forever Clear Anti-Mould Bathroom Sealant

Forever Clear Anti-Mould Bathroom Sealant
Another popular bathroom sealant is the Forever Clear formula. It’s available as a 295 ml tube for use with a gun or a smaller 80 mm squeeze tube for smaller jobs.

The Forever Clear is an anti-mold silicone mastic that’s perfect for areas of high humidity such as bathrooms and showers. It contains the brand’s patented “Mould Shield”, which actively prevents the growth of mildew, mould and bacteria.

Other features of the Forever Clear Silicone Sealant include:

  • Permanent waterproof and flexible seal
  • Certified under the harmonized European standard EN15651
  • Available in clear, white, grey or ivory
  • Touch dry in 15 minutes
  • Can be used indoor or outdoor

Overall, the Forever Clear bathroom sealant is a high quality silicone formula that can be used for almost every job that requires sealing.
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5. Gorilla Glue Mould Resistant Sealant

Gorilla Glue Mould Resistant Sealant
Gorilla Glue are a highly reputable brand in the UK and well-known for their high performance formulas. This mould resistant sealant is a great example of that reputation and is perfect for shower trays, baths, sinks and much more.

In terms of its usage, it’s a fast drying formula that’s water-ready in just 30 minutes and provides a long lasting finish that won’t turn yellow, shrink or crack.

Other features of the Gorilla Glue Mould Resistant Sealant include:

  • Versatile all-purpose sealant
  • Resists mould and mildew
  • Dries within 30 minutes
  • Lifetime guarantee
  • Suitable for indoor or outdoor use
  • Clear formulation
  • 80 ml tube

The Gorilla Glue sealant is an excellent all-round option that combines performance with value for the money. The fact that it comes with a lifetime guarantee is a clear indication of the high quality mould-resistant finish that it provides.
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6. 151 Bathroom Silicone Sealant

151 Bathroom Silicone Sealant
For smaller jobs that don’t need a large tube, it may be cheaper and easier to use a squeeze tube such as the 151 silicone sealant. It’s available in a 70 gram tube that includes an applicator nozzle and is very easy to apply.

Other features of the 151 Bathroom Silicone Sealant include:

  • Fully waterproof formula
  • Available in a clear or white finish
  • No gun required for application
  • Screw on applicator nozzle
  • Perfect for smaller jobs

Overall, the 151 formula is a cheap bathroom sealant that’s easy to apply and is designed for warm or humid environments. Whether you are sealing around a bathroom extractor fan or repairing tiles, it won’t disappoint.
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Bathroom Sealant Buying Guide

Applying a bathroom sealant adds to the finishing touches in your bathroom. There are plenty of options to choose from but we highly recommend that you keep with the reputable brands for peace of mind.

The purpose of the sealant is to seal surfaces in areas of high humidity. They help prevent bacteria and fungal growth and ensure maximum hygiene within your bathroom.

To help you make an informed buying decision, we have produced the below guide regarding bathroom sealants.

Caulk vs Silicone

Caulk is a popular method of sealing walls, ceiling and trim. It can also be painted over, which makes it easier to blend in with the rest of the room. However, it’s not the best option for bathrooms as it’s not completely water resistant.

A silicone sealant is the better choice for a bathroom because it provides a waterproof barrier against moisture. However, due to the moisture repelling property of a silicone, it means it cannot be painted over. Therefore, you will want to use a bathroom paint elsewhere in the room and seal the areas around the bath, sink and so on with the sealant.

Drying Time

The majority of bathroom sealants require 24 hours to completely dry but there are many fast drying formulas available. For example, the UniBond sealant is dry to touch in just 1 hour, which allows you to get on with other tasks.

Colours Available

Most manufacturers provide a range of different colours to match your bathrooms decor. The most common include clear, white, ivory and grey, which suit the majority of bathrooms.

The drawback of most sealants is that it cannot be painted over. However, if it is a major requirement, you can use an oil-based primer that can be painted over.

How To Use a Silicone Sealant

Application of a bathroom sealant isn’t as simple as spreading it on the surface and allowing it to dry. The surface needs to be fully prepared and the gun needs to be loaded with the sealant before you can begin.

Below is a brief guide to the steps required to use a seal surfaces within your bathroom.


Before you begin, it’s vital that the surface is well prepared and completely dry. The best option would be to completely remove old sealant, which will strip back all the grease and dirt. Once removed, you can clean the surface that’s to be sealed and allow it to dry out.

If you are worried that the surface isn’t completely clean, you can use a gel remover or even white spirit upon a damp cloth to wipe the surface.

Attaching to the Gun

If you are using a tube that requires a gun for application, you will need to correctly attach it to the gun. We recommend the following steps:

  1. Release the plunger by pressing the release at the back of the gun.
  2. Put the tube into the gun and push the plunger to the back.
  3. Cut the tip and push a nail through the hole to pierce the inner seal.
  4. Place the gun at a 45 degree angle along the joint width you want to seal.


Once the surface has been prepared and the tube is loaded within the gun,  you are ready to begin sealing. You will want to start in a corner and work across the length of the surface in a smooth movement.

If you are planning to seal a bath, we advise that you half fill it to prevent any movement once it has dried. After the sealant has completely dried, you can then empty the bath.


In order to prevent mould and mildew build-up, you will have to regularly clean the sealant. Soap and other residues can instigate bacteria growth upon the sealant but catching it before it begins to spread is highly advised.


Adding the finishing touch to your bathroom with a quality sealant is highly recommended. Without using a sealant, you leave areas exposed to moisture, which can lead to water damage and bacteria growth.

All of the recommendations are developed by reputable brands and suited to a range of budgets with formulas that can be applied by a gun or squeeze tube.

The Author Who Worked On This Article

author dan darimo

Dan Morgan

As a keen DIY’er, gardener and somebody that loves the latest tech, Dan is someone that brings years of experience in multiple trades. Since buying his first house, he has been obsessed with renovating properties and filling it with the latest products. This has led him down the road of testing hundreds of products and creating in-depth “how-to” and informative guides that offer his first-hand experience. Other interests include working on cars, keeping fit through sports or his home gym, caravanning and drinking great coffee.

If you would like to read more about Darimo and the authors, you can visit our about page. This goes into great detail regarding how we test products, create our guides and everything else.

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