The Ronseal 3-in-1 Mould Killer kills mould instantly, cleans and protects against mould. It breaks down mould and removes it from paint work. How to Use. Squeeze the trigger to break the tamper evident seal. Repeatedly squeeze the trigger, applying direct to the surface ensuring it is wetted thoroughly (wear suitable gloves). Leave for 5 minutes then wipe the surface using a damp cloth or sponge removing the mould. Once the mould has been removed, wipe away any residual grime with a clean damp cloth. Clean Up Rinse cloths or sponges in warm, soapy water. Usage Areas: For use in areas where mould is present.Compatibility: Suitable for use on, bare or previously painted walls and ceilings.Clean Up: Clean cloths and sponges in warm soapy water. Available in a bottle (concentrate) or spray.