Does Sunlight Darken Wood?

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If you’re a woodworker or someone who appreciates the natural beauty of wood, you may have questioned whether sunlight has the ability to darken wood over time. Wood is a natural material that can be influenced by various external factors, including exposure to sunlight.

Having an awareness of the potential aesthetic alterations caused by sunlight can assist you in preserving the visual appeal of wooden items. Continue reading to gain insights into this matter.

Can Sunlight Cause Wood to Darken?

Sunlight is one of the most powerful forces of nature, and it can profoundly impact the appearance of wood. Over time, exposure to sunlight can cause wood to darken, especially if a finish or sealant does not protect it.

In addition to causing color changes, sunlight can cause wood to dry out and become brittle over time. This can lead to cracks and splits in the wood, significantly reducing its strength and durability.

So, if you want to preserve the natural beauty of your wood, it’s important to take steps to protect it from the harmful effects of sunlight.

holding two woods

Effects of Sunlight on Wood and Factors to the Change in Color

Over time, exposure to sunlight can cause wood to change color, altering its natural appearance. This process, known as photo-oxidation, can be influenced by various factors, including the environmental condition, the degree of sunlight exposure, and the type of wood.

Understanding these factors can help you protect and preserve the beauty of your wood furniture, flooring, and decor for a very long time.

Degree of Exposure

The degree of exposure to sunlight is one of the most significant factors affecting the change in the color of the wood. When wood is exposed to sunlight for extended periods, it undergoes photo-degradation, changing its color, texture, and strength.

Wood directly exposed to sunlight, such as outdoor furniture and decking, is more susceptible to color changes than wood in shaded areas.

Regarding orientation, wood placed horizontally, like decking and flooring, is likelier to darken than wood installed vertically, like window frames and siding.

drying wood with sun heat

The degree of sunlight exposure can indeed vary based on factors such as the time of day and the season. These variations in sunlight exposure can have a significant impact on the rate and extent of color change in wood. 

For instance, wood exposed to intense, direct sunlight during the peak hours of the day may experience more pronounced color changes compared to wood that receives indirect or diffused sunlight. 

Similarly, the angle and duration of sunlight exposure can influence how quickly and intensely the wood’s color changes over time.

Condition of the Wood

The condition of the wood is a significant factor in the change in color of the wood when exposed to sunlight. Humidity, temperature, and age can all impact the condition of the wood and cause it to darken.

If the wood is in a humid environment, it will absorb moisture, which can cause the wood to swell and warp. In contrast, if the wood is in a dry environment, it can shrink and crack.

Furthermore, when the wood is exposed to high temperatures, it can cause the wood to dry out quickly, leading to cracks and splits. 

These cracks and splits can also cause the wood to darken, allowing more sunlight to penetrate the wood, causing the color to concentrate in certain areas.

The age of the wood can also impact the condition of the wood because as wood ages, it naturally darkens and becomes more brittle. When exposed to sunlight, older wood may darken more quickly than newer wood due to age-related changes in the wood’s structure.

standing wood piece

Type of Wood

Different wood varieties possess distinct characteristics that cause them to respond differently to sunlight. Certain types of wood exhibit higher resistance to sun exposure, while others are more susceptible to discoloration when exposed to sunlight.

Hardwoods like oak and cherry are more dense and have a tighter grain structure, making them more discoloration resistant. In contrast, softwoods like pine and cedar are less dense and have a more porous structure, which makes them more susceptible to discoloration.

Another factor that can influence the reaction of wood to sunlight is the tree’s growth rate. Trees that grow quickly tend to have a looser grain structure, making them more prone to discoloration.

On the other hand, trees that grow slowly have a denser grain structure, making them more resistant to discoloration.

What Causes Wood to Change Color When Exposed to Sunlight?

wood piece piling

Wood color change when exposed to sunlight is a natural process that can occur over time. The factors that contribute to this change include the type of wood, the amount of sunlight exposure, and the presence of certain chemicals in the wood.

The high-energy UV radiation in the sunlight can break down the chemical bonds in the wood, such as lignin, cellulose, and hemicellulose. As a result, wood that is exposed to sunlight over a long period can become darker, with a more pronounced grain and texture.

Another factor that can contribute to wood color change is the presence of certain chemicals in the wood. Some woods contain natural pigments or tannins that can react with sunlight to produce a color change.

Which Types of Wood Change in Color When Exposed to the Sun?

The effect of sunlight on wood can indeed vary depending on the type of wood. While most types of wood will undergo some degree of color change when exposed to sunlight, the specific alterations can differ significantly. 

These changes may encompass yellowing, darkening, or the development of a grayish or reddish hue, with the extent of transformation being influenced by the wood’s inherent properties and its susceptibility to ultraviolet (UV) radiation.

Here are some examples of wood species and how they may change in sunlight:

  1. Oak – tends to darken and turn yellow or reddish-brown over time
  2. Cherry – develops a warm reddish-brown hue
  3. Mahogany – becomes deeper and more reddish-brown
  4. Walnut – darkens and turns a rich chocolate-brown
  5. Teak – fades to a silver-gray color
  6. Cedar – turns a silvery-gray color
  7. Pine – may develop a yellowish or orange-brown hue
  8. Maple – can turn a slightly darker, amber color
  9. Ebony – can fade and lose its intense black color.
  10. Birch – can develop a yellowish or reddish hue when exposed to sunlight.
  11. Redwood – can turn reddish-brown or even black when exposed to sunlight.
  12. Douglas Fir – can darken and develop a more golden hue when exposed to sunlight.
  13. Ash – can turn grayish or even black when exposed to sunlight.
  14. Rosewood – can darken and develop a reddish or purplish hue when exposed to sunlight.
  15. Spruce – can turn yellow or even orange when exposed to sunlight.
  16. Hemlock – can develop a yellowish or brownish hue when exposed to sunlight.
  17. Alder – can darken and develop a reddish hue when exposed to sunlight.
  18. Beech – can develop a yellowish hue when exposed to sunlight for an extended period.
  19. Hickory – can lighten and develop a more golden hue when exposed to sunlight.
  20. Sapele – can darken and develop a reddish hue when exposed to sunlight.

Does Stained Wood Change Color in the Sun?

holding two pieces of oak wood

Yes, stained wood can still change color when exposed to sunlight. While the stain can offer protection against UV radiation, prolonged exposure to sunlight does darken wood over time.

In general, darker stains may fade more noticeably than lighter stains; some stains may be more resistant to UV radiation and fading than others.

It’s also worth noting that regular maintenance, such as cleaning and reapplication of protective coatings can help slow down the color-changing process in stained wood.

What Are the Methods to Prevent Wood from Darkening?

Wood is a natural material renowned for its beauty and versatility. Still, over time, it can lose its luster due to darkening caused by factors such as sunlight exposure, humidity, and oxidation.

Fortunately, several ways exist to stop wood from darkening and preserve its natural color and beauty. Following these tips can keep your wood looking vibrant and beautiful.

Use UV-inhibitor finishes

General Finishes Oil Base Gel Stain Antique Walnut

Preventing wood from darkening using UV-inhibitor finishes is a common and effective method. UV-inhibitor finishes, also known as UV-resistant finishes, are coatings that contain special additives designed to block the damaging effects of UV rays from the sun.

To prevent the wood from darkening, you can apply a UV-inhibitor finish to the surface of the wood. This finish will create a barrier that prevents UV rays from penetrating the wood fibers, thereby minimizing the effects of sunlight exposure.

Choosing a product suitable for the type of wood and the intended use is important for using UV-inhibitor finishes effectively. Additionally, it’s important to follow the manufacturer’s instructions for application and maintenance to ensure the best results.

With proper use and maintenance, UV-inhibitor finishes can effectively prevent the wood from darkening due to sunlight exposure.

Avoid Direct Sunlight on Wood.

splitting sweet gum wood

One of the simplest ways to prevent the wood from darkening is to avoid direct sunlight on the wood as much as possible. This can be done by placing the wood in a shaded area or using curtains or blinds to block direct sunlight from entering the room.

Another option is to use a protective covering, such as tablecloths or placemats, to shield the wood from direct sunlight. However, suppose the wood is installed outdoors, such as on a deck or patio.

In that case, you may consider adding an overhead covering or shade structure to block direct sunlight from reaching the wood, using an umbrella, awning, or pergola.

Although avoiding direct sunlight can help prevent significant darkening of the wood, exposure to sunlight does darken the wood.

Therefore, it’s important to consider other preventative measures, such as applying UV-inhibitor finishes or using wood sunblock, in combination with avoiding direct sunlight, to effectively prevent the wood from darkening.

Change Furniture Placement

moving furniture

Changing the placement of your wooden furniture can also help prevent it from darkening over time. If your wooden furniture is in direct sunlight, consider moving it to a spot with less sunlight. This could be a different area of the room or even a different room altogether.

Additionally, you can try rotating your furniture periodically so that different wood parts are exposed to sunlight at different times. This can help prevent uneven darkening and ensure that the wood maintains consistent color over time.

By being mindful of the placement of your wooden furniture and making small changes as necessary, you can help prevent it from darkening due to excessive sunlight exposure.

This simple and practical approach can help you maintain your wooden furniture’s beauty and natural color.

Cover Windows

Covering windows is another effective way to prevent the wood from darkening due to sunlight exposure. You can use curtains, blinds, or shades to block direct sunlight and UV radiation from entering your home and damaging your wooden furniture.

If you have large windows or glass doors that receive a lot of sunlight, consider using UV-blocking window films or tinting to reduce further the amount of sunlight that enters your home.

Add an Awning

making an awning

Adding an awning to your home can provide shade and protection for your wooden furniture from direct sunlight. An awning can help to block out the sun’s harmful UV rays, preventing the wood from darkening and fading.

You can choose from various awning styles and materials, including retractable [1] or stationery designs and fabric or metal options.

When selecting an awning, it’s important to consider the size and location of your windows and the direction of the sunlight to ensure your furniture is properly covered.

An awning provides shade for your wooden furniture and adds an aesthetic appeal to your home’s exterior. It’s a great investment for those who want to protect their outdoor furniture and keep their wooden furniture looking new.

Choose Low Emissivity Windows

installing wood windows

One effective way to prevent the wood from darkening due to sunlight exposure is by choosing low-emissivity windows for your home.

These windows are designed to reduce the amount of ultraviolet (UV) radiation that passes through them, which can help minimize the damaging effects of sunlight on your wooden furniture.

Low emissivity windows typically have a thin, transparent coating that reflects UV radiation out of your home rather than allowing it to penetrate through the glass. 

This can significantly reduce the amount of sunlight that enters your home and prevent your wooden furniture from darkening over time.

If you’re building or renovating your home, consider investing in low-emissivity windows as a preventative measure to protect your wooden furniture.

By reducing the amount of UV radiation that enters your home, you can help preserve the natural beauty and color of your wooden furniture for many years.

FAQ

Does heat darken wood?

Yes, heat can darken the wood. When wood is exposed to high temperatures, the heat causes the natural oils and resins within the wood to break down and oxidize, which can cause the wood to darken or even turn black.

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Conclusion

Extended exposure to sunlight can indeed lead to alterations in the color and appearance of wood. Nonetheless, there are several techniques at your disposal to mitigate or decelerate this phenomenon, thus upholding both the wood’s aesthetic charm and durability.

Although sunlight’s impact on wood may result in darkening, through diligent maintenance and protective measures, you can extend the wood’s lifespan while retaining its inherent allure.

Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
Robert Johnson

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