When the wood appears with severe mildew but does not lighten when tested with bleach, indicates they have undergone Darkening. This kind of darkening and decaying of wood generally has a solid and consistent appearance.

Possible Causes


• Exposure to UV (Ultraviolet radiation).
• Darkening occurs in wood never coated with protective coating (e.g. primer, paint or stain).
Do not expose new woods to weathering for longer periods of time.
Occurs under Clear varnishes and Lightly pigmented stains To achieve best paint and stain performance, coat the new surface before installation or immediately after installation.
Darkening happens in Different degrees on Different woods. Sand the wood to get a fresh surface, prior to priming the entire wood surface that has been allowed to weather.
Moisture Penetration in to the Wood causes varnish coatings to peel off due to wood decomposition under the coating. Discard the wood that cannot be sanded to fresh wood.
Woods Exposed to Weather are not protected against wood-destroying organisms. Such exposed wood decays eventually and cannot be coated. • Allow the surface to dry completely, before coating.
• Apply coatings to treated wood after the moisture content has dropped to a paintable level- usually 15℃ or below.
• Splash water on the surface to determine, if it is waterproof.
• If the water gets absorbed and surface becomes noticeably darker, the surface is not waterproof.
• This test is especially recommended for pressure-treated wood and smooth cedar.
• Ensure proper penetration of coating.

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