Understanding How Timber Weathers
Many homeowners and architects are searching for a low maintenance finish for their timber weatherboards or timber decking. Here’s what you need to know.
From our 15 years of experience, we’ve seen many leave their timber cladding and decking uncoated expecting it to evenly “silver off” but are left bitterly disappointed.
Equally, a clear coat of oil or lacquer will not account for uneven UV exposure and while a better option than simply leaving timber uncoated, will not get an even result. Depending on your choice of coating, clear coats of oil can actually encourage mould growth and discolouration.
How does weathering occur?
Timber going silver or grey is a natural process called oxidisation.
Sunlight produces a chemical reaction within the wood’s cellulose, which holds the color of the wood. Radiation from the sun’s ultraviolet rays breaks down the lignin in the cellulose causing photochemical degradation, and it occurs in any wood exposed to sunlight. The result is a change in the wood’s appearance from its original colour to a gradual silvery grey sheen.
In areas of high rainfall some timber cladding installations can turn grey in just a few months, whilst in drier areas the process is likely to be slower.
Similarly, south and west facing walls weather relatively fast, due to their exposure to sunlight, whereas east and south facing walls tend to weather more slowly, but uniformly.
The design of a building also determines how it will weather, as the form and shape influences the impact that wind-driven rain will have on it. For example, buildings without eaves tend to get wettest at the top, particularly at the outer corners, so this may result in these areas weathering more quickly than other parts of the wall.
If there are eaves then uneven weathering can occur (unless the eaves shelter the entire wall) as sunlight will be unable to reach the areas under these eaves.
There may also be areas which, due to the design of the building, are subject to water splashing – this can also lead to the wood weathering faster in these areas.
If left uncoated, over time, the entire building (unless completely sheltered from the elements) will weather to the same colour, and will remain the same silver-grey colour for years to come. Timber will vary in appearance depending on the quantity of moisture on the surface (when it is wet, the timber will appear darker in colour).
Protected areas like eaves will filter or block light causing discolouration.
After years of development work Abodo has options to solve this challenge.
Our flagship Vulcan Cladding has a propensity to evenly silver off and lends itself well to shades of grey. This can be managed by the use of a penetrating oil.
The two recommended options to achieve an even grey facade or deck are below:
Pigmented Penetrating Oil - Protector Oil
Pre-finishing timber cladding or decking in a shade of grey pre-empts the natural aged colour of the timber. As timber ages naturally, it forms a silver ‘patina’ as the surface of the wood oxidises. This thin film actually helps to protect the wood during the weathering process. This is commonly known as “silvering off”.
Abodo’s Protector Oil is available in pigments of Pearl, Patina and Graphite. Protector Oil contains plant based oils which penetrate into the wood, while leaving a pigment on the surface of the wood.
As the timber gets weather, the timber substrate will lighten, leaving the titanium dioxide pigments to ‘pop’ and provide a fresh silver surface. The mouldicides used in Protector Oil provide a broad spectrum protection against surface mould and discolouration.
Choose Pearl for a mid grey (perfect for decking) or Patina: a lighter grey. A darker gun metal grey can be achieved with Graphite.
Choose to have your Abodo decking or weatherboards factory pre-finished with Protector Oil and create a modern “weathered” look.
Clear Penetrating Oil - Protector Oil
For a more natural weathered look Clear Protector Oil can be applied. The water barrier composition in Protector Oil helps provide water repellency, and an enhanced fungicidal package ensures superior exterior performance – and resistance to mould. The use of Clear Protector Oil will keep Vulcan Cladding “fresh”, while allowing it to fade gradually. This finish will not be as even as pigmented Protector Oil options.