1. Fix the Cause: 

Address the root cause(s) of the black mould (such as leaks, poor ventilation, or high humidity) before proceeding.

2. Prepare the Surface:

• Clean the affected area thoroughly with a fungicidal wash to remove existing mould.

• Allow the surface to dry completely.

3. Apply G21:

• First Coat: Apply the first coat of G21     using your chosen method: paintbrush, roller, or air-feed paint gun.

• Second Coat: If required, apply a second coat once the first coat is dry.