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Things to consider when choosing your sanitary sealant

There are various aspects to consider when choosing the best sanitary silicone for you.

Multifunctional and good adhesion

Your sanitary sealant must be multifunctional. It should work well with different kinds of surfaces and offer excellent adhesion to each. Non-extended sealants should be used that do not contain solvents, stick better, and have no reduction in volume after application.

We have two sanitary sealant technologies, acetoxy and neutral cure, both of which have a durable and proven adhesion to a variety of sanitary surfaces.

Choosing the right sealant can ensure it does not affect any substrates to which it has been applied. If you have any concerns whether your sealant will damage your surfaces, please contact our experts.

Material and finish

Today, sanitary fittings are available in a variety of materials including ceramic, enamel, glass, metal and stone, as well as various finishes. When it comes to sealing the joints around your sanitary fittings, it is important that the sealant is matched to your surroundings, in terms of both material and finish.

For traditional materials like ceramic, enamel or glass joints, you can use a silicone sanitary sealant with no dilutions. This will offer the best finish and will form an elastic rubber seal when applied.

For modern materials like plastic and metal, it is important to use a neutral cure sanitary sealant. This will adhere best to these surfaces as well as curing under humid conditions.

For porous materials like natural stone, it is important to use a non-staining, plasticiser-free, neutral cure silicone sealant. This will help avoid the risk of soiling at the edges or staining during the application process. Once adhered, it will form a permanent rubber seal.

Anti-mould properties

Sanitary areas are often dark and have high humidity, creating the perfect conditions for mould and bacteria to thrive. To ensure maximum hygiene, it is critical that your sanitary silicone contains fungicides to inhibit mould and bacteria growth.

All Bostik sanitary sealants contain fungicides. Our technology ensures any traces of mould that settle on the surface of the sealant are restricted in their growth and prevented from developing further.

By inhibiting bacteria and mould growth which can stain or cause discolouration, our sealants help achieve a long-lasting, professional finish.

Bostik's advice to prevent mould is to keep humidity below 65% by proper ventilation and avoid cleaning with chlorinated products.


Another important requirement is the ability to cure perfectly well under humidity. Sanitary areas are often very humid, so you need to be able to apply your sealant in these conditions and for it to dry quick enough to stop bacteria and mould from growing.

Plus, the longer the drying time for the sealant, the greater the chance that dust and dirt can attach to its surface affecting the quality of the finish.

Bostik’s sanitary sealants will skin over in as little as 5 minutes, and will cure at a rate of 2-3mm/24 hours. Factors such as how much sealant is applied and where it is applied can affect the drying and curing times.

Lowest possible VOCs

As well as ensuring your product dries quickly, it is important to choose a product that has the lowest Volatile Organic Compounds (VOC) content when sealing sanitary joints.

Once the sealant is applied, VOCs evaporate into the environment, which can be detected due to a slight odour.

All of Bostik’s sanitary sealants are manufactured with the lowest possible VOCs and feature certifications such as EMICODE EC1 for indoor air quality.

How to prepare before applying a sealant to sanitary joints

Now you know the best sanitary sealant for you, it’s important to understand the pre-application steps to take before you start sealing sanitary joints.
  • Check the substrates of your tiles or other materials before purchasing sealants. A simple way to do this is to add a drop of water on the surface and see if the drop is absorbed or beads on the surface. If it gets partially or fully absorbed then the material is porous. If not, then it is non-porous. Choose products accordingly.
  • For shiny, flat surfaces, 100% silicone-based sealants will give a better aesthetic finish.
  • Before applying any sealant, ensure the surface is clean and dry. For porous surfaces, remove any dust with a clean cloth. For non-porous substrates, use a cloth and clean with Isopropyl Alcohol (IPA).
  • Optional, place masking tape along the joint edges before application. This can make it easier to make a neat, tooled finish and not contaminate nearby surfaces.
  • Use Bostik T500 FINISHING SOAP or soapie water to smooth the joint.
  • Within the working time of the product, it is easy to smooth the sealant with a wet, round-ended tool (do not use a wetted finger). Check that it fits into the gap between the masking tape so that it catches the excess sealant.

Everything you need to know before sealing sanitary joints

Which sealant should you choose?

With ceramic, enamel or glass joints, it is important to use products  that would offer good adhesion as well as be able to resist humidity and water.  Sealants that contain 100% silicones with no dilutions will offer the best finish and will form an elastic rubber seal when applied. You need a versatile sealant that cures under humidity and is mold free.
Sanitary joints are continually exposed to moisture and humidity. Some materials including metal may also be subject to corrosion. A 100 % silicone sealant that adheres well with different surfaces and cures under humidity is fit for use in this case. You need a versatile neutral silicone sealant.
Natural stone surfaces look beautiful but are often porous and therefore at a risk of getting soiled, at the edges, or stained while applying sealants. You also need to ensure that the sealant applies smoothly, adheres well to the surface and forms a permanent rubber seal. You need a non-staining, plasticizer free, neutral silicone sealant.

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