Ensure that the substrate is clean, dry and free from oil, grease and any other contamination such as moulds and fungal growth. Remove oily deposits by washing surfaces with white spirit. Any fungal deposits should be treated with either a proprietary fungicide, such as Bondall’s Mould & Moss Eliminator, or diluted household bleach (1 part bleach : 4 parts water). Treated areas should be rinsed thoroughly with water. Allow to dry for at least two days.
As Thompson’s Water seal will not fill cracks or gaps carry out any necessary repair work before its application.