If you mean mildew growing on the silicone sealant around a shower or bathtub, the fastest approach depends on whether the mildew is only on the surface or has penetrated the silicone.
🚿 If it’s surface mildew
Ventilate the bathroom and put on gloves.
Clean away soap scum and dirt first with a bathroom cleaner.
Apply a mold/mildew cleaner labeled for bathroom silicone and follow its contact-time instructions.
Scrub gently with an old toothbrush or small brush.
Rinse thoroughly and dry the silicone completely.
Keep the shower well ventilated afterward and dry the seal regularly.
Never mix bleach with vinegar, ammonia, or other cleaning products. Dangerous gases can form.
🦠If the black staining is inside the silicone
This is the important part: if the silicone remains black or discolored after thorough cleaning, the mildew may have penetrated the sealant. Cleaning the surface won’t reliably remove it.
In that situation, the durable solution is to:
Cut out the old silicone completely.
Clean and disinfect the underlying surface appropriately.
Allow everything to become completely dry.
Apply new 100% bathroom/sanitary silicone according to the manufacturer’s instructions.
Trying to paint or simply apply new silicone over contaminated old silicone usually doesn’t solve the problem.
How to stop it returning
The biggest factors are moisture and poor ventilation. Use the bathroom exhaust fan during and after showers, leave the shower area open to dry, remove standing water, and repair leaks promptly.
If the mildew covers a large area, keeps returning despite cleaning, or you suspect moisture behind the wall, professional assessment may be worthwhile.
