Uncoated, weathered cedar can often be restored to its original colour by applying commercial products called cleaners, brighteners or restorers. Although intended primarily for restoring horizontal wood surfaces, they generally work almost as well on vertical surfaces. Some products are formulated with thickening agents to help the liquid cling better to vertical surfaces. The manufacturer’s instructions should be followed for optimum effectiveness.
Commercially available cleaners and restorers generally fall into three categories: paint strippers, bleaches, and oxalic acid-based formulae. These products contain hazardous ingredients and should be used with caution.
Paint strippers will also remove oil-based stains and latex stains. Most are supplied as ready-to-use liquids. After use, residual stripper should be thoroughly rinsed from the wood surface before any other coating is applied.
Bleaches are effective in counteracting mildew but do little to remove dirt or other surface deposits. Aggressive scrubbing with caustic cleaners such as bleach will remove surface wood fibres and result in the wood having a rough, unnatural whitish tone.
Oxalic acid-based products remove extractives bleed and iron stains but are not effective against mildew. After application of these products the wood should be thoroughly washed with clean water and allowed to dry completely before finishing.