Intergrain UltraPrep Timber Cleaner is a high strength cleaner that restores grey, rust or tannin stained, mould or mildew affected timber to a clean appearance suitable for coating.| Reviva is also used to clean and prepare new timber for coating by removing the dirt, tannins, oils and other contaminants that are present.| Intergrain Reviva has a non-bleaching formula and contains oxalic acid, which is a naturally occurring, bio-degradable organic acid.