Black mould spots on sealant edges along shower trays, washbasins or worktops are often caused by traditional silicone sealant, which is notably susceptible to mould growth. A modern alternative is MS polymer sealant (such as Inducoat MSP2.0): no plasticisers that serve as a nutrient source, better adhesion and can be overpainted with a mould-resistant coating.
Why mould develops on silicone sealant
Silicone sealant was the standard in wet areas for years, but it has disadvantages that encourage mould growth: organic plasticisers form a nutrient source, the sealant adheres poorly to damp or porous substrates (resulting in small leaks and moisture accumulation), the sealant layer cannot be overpainted and loses its protective effect over time. Cladosporium and Aspergillus in particular then become established in and on the sealant — and once established, they are difficult to remove without the right technique.
Why MS polymer sealant is more resistant
MS polymer sealants such as Inducoat MSP2.0 offer a structural solution. They contain no plasticisers or solvents that feed mould, adhere extremely well to virtually all substrates (including slightly damp ones), can be overpainted with a mould-resistant coating, and remain elastic and durably resistant to mould growth over the long term. Combined with a mould-resistant wall paint, this creates a more hygienic seal that requires less maintenance.
How to replace silicone sealant
- Remove the old sealant completely using a plastic sealant remover or knife.
- Clean and degrease the surface thoroughly (using a suitable cleaning agent or alcohol).
- Disinfect if necessary with a suitable cleaner, such as Inducoat Cleaner.
- Allow everything to dry thoroughly.
- Apply the MS polymer sealant neatly with a sealant gun.
- Smooth it with a wet finger or plastic spatula.
After curing, the new joint not only looks attractive but is also more resistant to mould formation over the long term.
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