Black silicone in bathroom joints — around the bath, shower tray, or basin — is one of the most common complaints from UK homeowners. Once silicone goes black with mould, it’s virtually impossible to return it to its original white or clear appearance. The question is whether it can be treated or whether it needs to be replaced entirely.
Why Does Bathroom Silicone Go Black?
Bathroom silicone is an ideal environment for mould growth: it’s warm, regularly wet, and the surface of silicone is slightly porous over time. Black mould (typically Cladosporium or Aspergillus species in this context) establishes itself on and within the silicone surface, causing the characteristic black staining.
The mould grows into the structure of the silicone itself — which is why bleach-based cleaning products only bleach the surface rather than killing the mould at its roots. Within a few weeks, the black colouring returns.
Can Black Silicone Be Treated?
Short answer: not reliably. Products marketed as “mould and mildew remover” will temporarily lighten the staining, but because the mould has penetrated the silicone structure, it regrows. For cosmetically clean, hygienic results that last, the silicone needs to be removed and replaced.
Silicone Replacement: What’s Involved?
Removing old silicone and applying fresh sealant is a straightforward process for a professional:
- The old silicone is cut and peeled away using specialist tools
- The joint surfaces are cleaned and dried thoroughly — any remaining residue is removed with solvent
- Fresh silicone is applied in a clean, even bead
- The bead is tooled smooth and left to cure (typically 24 hours before getting wet)
Using mould-resistant silicone (which contains a fungicide) and ensuring adequate bathroom ventilation will significantly extend the life of the new sealant.
Prevention: Stop the Mould Coming Back
- Use extractor fans during and after bathing
- Leave the bathroom door open after showering to allow airflow
- Wipe down wet silicone joints after bathing
- Use a mould-resistant silicone at application
- Avoid leaving wet bath mats against silicone joints
Shazam Repairs includes silicone replacement as part of our bathroom restoration and tile repair services. Get a quote →
