What causes the grey look on wooden decks?

Outdoor wood exposed to sun, rain and temperature fluctuations undergoes a natural ageing process. The main cause of greying is UV radiation, which breaks down the lignin in the wood. Lignin, together with cellulose, gives wood its structure and strength. When lignin is degraded by UV light, it is washed out by rain and moisture, leaving the surface faded and grey. In addition, dirt, algae and fungi accumulate more easily on weathered surfaces, which further intensifies the grey colour. Without protection or maintenance, this greying can appear within just a few months, especially with softwood species. Decks, cladding and garden furniture lose their warm appearance and natural charm. Simply rinsing with water won’t remove the grey layer, as it penetrates deep into the wood fibres. A specialised treatment is needed to restore the original wood surface and prevent further damage.

Woca Exterior Deep Cleaner removes greyed wood and surface dirt, restoring the original appearance.

Woca Exterior Deep Cleaner is designed to deeply clean and restore weathered and dirty outdoor wood. This ready-to-use gel has a high viscosity and is easy to apply, even on vertical surfaces. Thanks to its deep-penetrating action, it removes not only dirt and algae but also greyed wood and old oil residues. The surface must be thoroughly wetted before applying the product with a brush, roller or sprayer. After 15–20 minutes, scrub the wood with a stiff brush – preferably a WOCA silicon carbide brush – and rinse thoroughly with water. For long-lasting results, treat the surface with WOCA Exterior Wood Oil after at least 48 hours of drying. This combined approach gives outdoor wood a second life and long-lasting protection against the elements.