BOSTIK Pro-Sealant S21 Multi-Purpose Acetoxy Silicone Sealant, Clear, 310ml
Pros
- Multi-purpose formula suits glazing, frame and sanitary joints
- Rated for both internal and external use
- Clear finish blends in around windows, doors and worktops
Cons
- Acetoxy cure gives off a vinegar smell while curing
How it compares in Adhesives & Sealants
We list 42 adhesives & sealants products, priced from £3.47 to £47.95. At £10.21 this one is the 28th cheapest of them — 14 cost more. The average across the subcategory is £10.44 and the midpoint is £8.96, so it lands almost exactly on the average.
Its 4.4-star score sits 0.16 below the adhesives & sealants average of 4.56, with 38 of the 42 rated higher. Its 180 Amazon reviews make it the 42nd most-reviewed here, against a subcategory average of 2,868.
Price position in Adhesives & Sealants
Splitting the subcategory into three price bands puts this product in the Mid-range band (£6.99–£10.21), which holds 12 of 36 products and averages £8.81 at 4.56 stars.
| Band | Range | Products | Average price | Average rating |
|---|---|---|---|---|
| Budget | £3.50–£6.50 | 12 | £5.56 | 4.57 |
| Mid-rangeThis one | £6.99–£10.21 | 12 | £8.81 | 4.56 |
| Premium | £10.54–£52.00 | 12 | £16.77 | 4.57 |
About this product
The Bostik Pro-Sealant S21 Multi-Purpose Acetoxy Silicone Sealant offers a robust solution for waterproofing and bonding applications where protection against mildew is essential. This sealant is formulated to provide long-lasting defence in humid environments, making it ideal for use around bathrooms and kitchens, particularly with sanitaryware like baths, basins, showers, and toilets. Its versatile design caters to both internal and external projects, offering peace of mind across a range of sealing needs.
This clear silicone sealant utilises an acetoxy cure which is resistant to UV rays, rain, and snow, ensuring durability even in exposed conditions. The formulation boasts a low modulus, providing high elasticity and fast skinning times for efficient application and rapid curing. It’s designed for primerless adhesion on common construction materials including glazing, frame and glazed tile surrounds, simplifying the project process.
The sealant is supplied in a 310ml PCR cartridge – Post Consumer Recycled – with a black colour. The contents include one S21 Acetoxy Silicone Sealant unit within this cartridge. It’s a suitable product for DIY enthusiasts undertaking home improvement projects and professionals requiring a reliable sealant for waterproofing joints and bonds.
Please note that the acetoxy cure process releases a slight vinegar-like odour during curing. Consider this when planning your application, particularly in enclosed spaces. For further details on warranty or returns, please refer to Amazon’s standard terms for purchases made through their platform.
Related attributes
Power
FAQ
What materials is the Bostik Pro-Sealant S21 suitable for?
This sealant is formulated for use on shower trays, basins, toilets, glazed tile surrounds, and other sanitaryware. It provides primerless adhesion to most common construction materials like glass and ceramic, making it a versatile choice.
What size is the sealant cartridge?
The Bostik Pro-Sealant S21 comes in a 310ml PCR cartridge, offering sufficient volume for typical bathroom and kitchen sealing applications.
Is this sealant suitable for external use?
Yes, it’s rated for both internal and external applications, including areas exposed to rain and snow due to its UV-resistant formulation.
What kind of smell does the sealant have while curing?
The acetoxy cure process results in a noticeable vinegar-like odour during the initial curing phase. This is typical for this type of silicone sealant and should dissipate as it fully hardens.
How does this compare to other sealants around £8?
The Bostik Pro-Sealant S21 offers a good balance of performance and price, particularly given its mould-resistant properties and UV resistance. It’s comparable to many sealant options in the mid-range category.
What should I do to maintain and clean this sealant?
Regular cleaning with soapy water is recommended to keep the sealant surface clear. Avoid harsh chemicals or abrasive cleaners that could damage the silicone.
Is this sealant waterproof?
Yes, it’s formulated as a waterproof sealant, providing effective protection against water ingress in applications like shower trays and basins.
What is the 'low modulus' feature of this sealant?
The low modulus allows for high elasticity, ensuring the sealant can stretch and contract with movement without cracking or losing its seal. This contributes to a fast skinning time and final cure.
Does it offer protection against mould?
Yes, the sealant contains a powerful fungicide agent, helping to prevent unsightly mould and black spot growth in humid environments such as bathrooms and kitchens.
What is the colour of the cartridge packaging?
The PCR Cartridge has a Black colour.
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