How Wood Flooring Naturally Changes Colour Over Time

By Andrew Zheng

Wood is revered for its beauty and ability to add warmth and character to a home. But like all natural materials, wood is subject to change over time, particularly when exposed to ultraviolet (UV) light. This process, called photosensitivity, is normal.

While many people embrace the changes that occur when wood ages, as it can add a unique patina and charm, others are not a fan. Thankfully, there are a few things that can be done to prevent or slowdown the process.

But first, what is photosensitivity?

Photosensitivity is the degree to which wood changes colour when exposed to light. The more photosensitive a wood species is, the more rapidly it will change colour.

The term ‘photochemical reaction’ is used to describe the process by which light energy causes chemical changes to occur. A good example is how sunlight causes the skin to tan. The photochemical reaction in wood is much more gradual and poorly understood. However, it is known that certain extractives in wood are responsible for its photosensitivity.

The most common change is wood will become darker in colour. This change and how quickly it occurs depends on the type of wood, finish and amount of sunlight exposure. For instance, light-coloured woods like birch and maple will change colour more rapidly than dark woods like walnut and mahogany. This is because lighter woods have a higher degree of transparency, meaning the wood grain is more visible and reacts more to sunlight and other environmental elements. Dark woods have a lower degree of transparency and are less affected by sunlight. This is why they often have a richer colour that lasts longer.

Some species also change colour considerably, especially exotic woods like Jatoba and Tigerwood. In time, they may appear a completely different colour. For example, Jatoba becomes a darker, almost vibrant red.

Interestingly, walnut is the only wood that becomes lighter, turning a golden-brown tone.

Here’s how light affects other woods:

• Beech changes to a medium degree, with the orange colour fading slightly and ambering
• Maple becomes more golden
• Cherry changes very fast and dramatically to a dark reddish colour
• Ash goes from a lighter tone to a straw or tan colour
• Jarrah becomes much darker
• White oak darkens or takes on a more amber tone

As a retailer, it’s important to inform customers that their wood flooring will transform with time. And they shouldn’t be surprised when their brand-new wood floor is a different colour than the aged sample floor in the showroom. Eventually it will catch up.

While little can be done to completely prevent the discolouring process, there are a few things that can ensure the floor at least changes colour evenly, so that some areas aren’t much darker than others. For instance, window treatments like curtains and blinds can filter sunlight and help block some UV rays that cause fading. And furniture and rugs can be rearranged periodically. This will help distribute the light evenly and prevent any area of a room from getting too much exposure.

Andrew Zheng is vice-president of Unique Wood Floors, a hardwood flooring specialty store located in Minneapolis and St. Paul, Minn. By sourcing wood using the most rigorous North American standards for precision milling and kiln drying in the hardwood flooring industry, Unique Wood Floors is able to offer high-quality flooring direct to customers’ curbside. Andrew can be reached at 952-994-9696.

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