Overview
- Mid-June coverage of UK sealant specialists identifies microscopic water ingress behind degraded silicone as the key cause of persistent black mould on bath and shower joints.
- Experts say bleach and surface scrubbing usually only remove visible stains because they do not stop water reaching the failing sealant, so mould commonly reappears within weeks.
- A self-adhesive silicone bath strip, sold for about £1, is recommended as a physical cap that sits over existing sealant to prevent further water penetration and block mould’s moisture source.
- A cheap bicarbonate-of-soda paste (about 65p for 200g), mixed with water, is advised for removing visible mould by applying, leaving 5–10 minutes, scrubbing, rinsing and repeating if needed.
- Proper drying is essential: allow cleaned or prepared sealant to dry fully (experts recommend around 12 hours before applying a strip) because trapped moisture undermines adhesion and invites regrowth, and the problem often appears 6–12 months after installation with higher risk in cooler months.