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