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Why Does Wood Turn Grey? | Prevent or Embrace the Weathered Look

Why does wood turn grey?

The greying of wood, often referred to as “natural weathering,” is primarily a result of exposure to sunlight and rain. Ultraviolet (UV) rays break down the wood’s surface lignin, a component that gives wood its colour. As this lignin degrades, the wood begins to lose its original colour, adopting a silver-grey patina. Moisture from rain can further accelerate this process, washing away the degraded lignin and exposing the wood’s cellulose fibres. The end result is a gracefully aged appearance that is loved by many, but not by others.

Factors contributing to wood greying

While the process may seem straightforward, there are a range of factors contributing to timber weathering. Here’s a deeper dive into the primary players in this natural transformation.

UV exposure

The sun’s UV rays play a critical role in the greying of wood. These rays penetrate the wood’s surface and break down the lignin—the component that imparts colour to the timber. As this lignin degrades, the wood loses its inherent colour, making way for the silver-grey patina. Over time, continuous UV exposure can result in a uniform greying, especially in areas that are directly and consistently exposed to sunlight.


While timber has a natural affinity for moisture due to its porous nature, this relationship becomes a bit tumultuous when it comes to greying. Rain, dew, and even high humidity can exacerbate the lignin breakdown process initiated by UV exposure. Moisture not only accelerates lignin degradation but also washes away the broken-down components, exposing the underlying cellulose fibres. This repeated wetting and drying cycle furthers the greying process, especially in climates with frequent rain or varying humidity levels.


Oxygen, an ever-present component in the atmosphere, also plays a part in this narrative. When timber is exposed to air, especially in the presence of sunlight and moisture, the oxidation process is set into motion. This chemical reaction contributes to the changes in wood’s colour, complementing the effects of UV degradation and moisture-induced weathering. Over time, oxidation can give timber a slightly bleached appearance, which further adds to its aged look.

How to prevent wood greying

The gradual shift of timber to a silvery-grey hue might not be desired by everyone. For those seeking to preserve wood’s original splendour or slow down its inevitable ageing, several protective measures come to the rescue. Here’s how you can shield wood from the relentless march of time and elements:

  1. Sealants and finishes: one of the most effective strategies is the application of sealants or finishes. These products form a protective barrier on the wood’s surface, safeguarding it from UV rays and moisture. Clear UV-resistant finishes or sealants are particularly effective as they filter out the harmful ultraviolet radiation, slowing down lignin degradation. Regularly reapplying these finishes ensures continued protection.
  2. Water-repellent treatments: moisture accelerates wood’s greying process, so reducing its ability to penetrate wood is crucial. Water-repellent treatments make wood more resilient to moisture, preventing the associated degradation and wear. These treatments are especially beneficial in regions prone to frequent rain or high humidity.
  3. Stains and pigmented finishes: these serve a dual purpose. Not only do they offer a fresh tint or restore the original colour of the wood, but they also provide an added layer of protection against UV rays. The pigments or dyes in these finishes absorb and reflect ultraviolet radiation, safeguarding the lignin beneath.
  4. Regular maintenance: like any other material, timber benefits from regular care. Cleaning the wood surface periodically with a gentle brush or soft cloth removes dirt, grime, and microbial growth, all of which can contribute to its premature ageing. For decks or outdoor furniture, occasional gentle washing with mild soap can keep the wood looking vibrant.
  5. Strategic positioning: if possible, position wooden installations or furniture in a way that they’re shielded from direct and prolonged sunlight. Using shades, awnings, or other protective covers can considerably reduce UV exposure.
  6. Anti-oxidation treatments: these treatments, which are often part of high-quality sealants and finishes, counteract the effects of oxidation on wood. They work by neutralising free radicals and other oxidative agents, ensuring the timber remains resilient against this form of ageing.

Embracing the weathered look

While greyed wood invokes images of the past, it’s perfectly suited for modern designs. Its neutral shade is a favourite in minimalist and contemporary setups, providing a natural contrast to more industrial materials. Discover three examples of Mortlock Timber projects that embraced weathered timber as part of their designs.

Research Primary School

Research Primary School - Timber Wall by Mortlock

The architect of this contemporary building at Research Primary School decided to opt for Blackbutt Fine Sawn cladding from our Trendplank range. This type of timber weathers beautifully into a silver grey, offering a sleek contemporary look for years to come. In addition, our Sioo:x protection system ensures the exterior wood weathers without the timber itself breaking down.

Jan Juc Studio

Burnt Ash Battens

Jan Juc Studio in Victoria is another example of how the weathering process has been used to improve the exterior design of a building. The Burnt Ash battens, combined with a weather protection coating, ensure the timber weathers to a light grey while offering protection to the cladding itself.

Scarborough Beach SLSC

Scarborough Beach SLSC during the evening

Finally, we have the Scarborough Beach SLSC located in Western Australia. Buildings located near the coast are expected to undergo heavy weathering because they are more exposed to the elements. Instead of fighting this natural process, the architects decided to embrace weathered wood and chose Pacific Teak battens and cladding from our Proplank and Trendplank ranges. The result was a gradual change from the wood’s original colour to a grey timber appearance.

Design with Mortlock Timber

At Mortlock Timber, we supply a variety of external timber cladding options to match both lovers of weathered timber and those who act to prevent it. We work closely with architects and designers to suggest the best timber products to make their projects come to life. From selecting the right timber species to choosing the perfect finish, the team at Mortlock Timber is here to help.

Contact us today for any information regarding our products or for a quotation. One of our friendly staff members will be happy to assist you!

View our pricing and product guide

For in-depth information about the range of products we offer, please fill out the form below to download our Architectural Timber Pricing and Product Guide. Inside you will find illustrations, specifications, portfolio photo examples and a hardwood timber price guide to assist with budgeting.


    Mortlock Timber

    We are committed to bringing you timber products that add value and endure for years to come, even in heavy traffic and harsh weather conditions. We understand the value of efficiency when it comes to installation and keeping hardwood timber costs down. That’s why we’ve spent decades perfecting our designs to make them easier to handle, less wasteful and more efficient to install. This efficiency allows us to offer you premier products that are more cost-effective so that you can experience greater savings on timber wall costs, timber ceiling costs, timber cladding costs and timber decking costs.

    Download our Pricing and Product Guide for our complete hardwood timber price list including timber decking prices, timber wall prices, timber ceiling prices and timber cladding prices.