Why Does Wood Turn Grey? The Natural, Weathered Look of Wood

The fresh, natural look for wood exposed outdoors as decking or siding has been popular for a long time.

Just take a look at this video to see why one particular homeowner wanted their deck to mature to that smooth silver patina:

As valued as this natural look is, protecting it is necessary to maintain the natural physical properties like durability and strength. We are going to try to explain some of the finishing that both protects the surface and maintains a pleasing appearance.

But first…

Why Does Wood Turn Grey?

The natural weathering process of wood is a combination of chemical, mechanical, biological and light-induced changes, all of which occur simultaneously and affect each other.  For instance, as air moves over the surface of a wood deck, dust, pollen, dirt, and air pollutants replace the exposed colored cells of the wood. This slow transformation is also made possible through the exposure of the sun’s ultraviolet rays, or salt particles in coastal areas. Depending on the species of wood, these changes can occur anywhere between a few months to years.

How Can You Prevent Wood from Turning Grey?

Keeping the natural look of freshly cut hardwood requires the use of a finishing product to block or slow the action of moisture and sun.

In the past, many of the products used to coat wood were very toxic and with a high content of volatile organic solvents linked to health problems; the new wood finishes are now low in VOC’s and safe for the users and the occupants of the building.

What Is a Wood Finish?

A finish is a liquid, paste, or gel that must be applied thinly and evenly onto the surface of the wood. Finishes can enhance the appearance of the wood and help defend against the detrimental effects caused by the sun’s ultraviolet rays.

With the correct type of finish, a natural weathered look can be achieved while providing protection for the siding to promote optimum performance over the years.

Natural wood finishes can be:

• Clear Water Repellents

Clear water repellents are one way to achieve a natural look; they do not add color and grain patterns can be seen through the finish.

However, most clear water repellents do not prevent the sun’s UV radiation from fading the wood since they don’t contain UV inhibitors. For exterior applications, you can expect clear water repellents are to last from 6 months to 2 years, depending on the surface texture of the wood and exposure to the sun.

• Weathering Stain or Bleaching Oil

When you use bleaching oil on softer woods like Redwood, or Cedar, you will find out that the grey weathered look happens faster and the protection offered is longer lived than a clear water repellent. The reason for the faster transformation is because the oil is essentially a water repellent finish containing some gray pigments. You will notice that as soon the bleaching oil is applied the softer wood almost immediately starts to turn grey. Then, as the wood is exposed to sun and water, the bleaching oils begin to bleach the wood itself, resulting in a uniform weathered look.

The protection of these oils last only two or three years, periodically apply a clear water repellent to the siding over the bleaching oil, to protect it but be careful in not altering the color. If alteration in color occurs, just apply another coat of bleaching oil.

Due to the intense density of exotic hardwoods like Cumaru or Ipe wood, bleaching agents don’t work very well.

• Stains

Stains are pigmented finishes that provide color and protection against UV rays. Some are water repellent and may include preservatives and mildewcide. They are classified in solid-color stains,  heavy bodied stains, and semitransparent penetrating stains.

Solid color stains, are opaque finishes. Surface texture is visible but wood grain and colors are not through this type of stains. They come in water-based and oil-based formulations. Service life is typically three to seven years, depending of the surface textures, exposure to elements and previous application.

Semitransparent penetrating stains have a moderate amount of pigment. Provide a uniform color without hiding the wood grain. Oil-based semi transparent is recommended since they penetrate the wood surface deeper than water-based products.

Another advantage with this type of stain is that they are not film forming which means no peeling or blistering but do wear off gradually, semitransparent penetrating stains are expected to last from two to five years, depending on the surface texture of the wood.

If applied to wood decking, these types of stains may last two years, subsequent applications may last up to five years.

It is recommended to avoid the use of varnishes, lacquers or other clear film-forming finishes, because they allow UV degradation, can crack and peel, and are difficult to remove.

Working With the Best Deck Oil for Exotic Wood

Ipe Oil™ is specially formulated to penetrate dense hardwoods. It is the best product to use on exotic woods that need nourishing and stabilizing. Its formula will not create a surface film that will crack, bubble, or peel. Also, its transparent natural tone allows the beauty of wood to be seen while also protecting the surface from the sun’s ultra violet rays. Ipe Oil™ also allows the wood to breathe, which is very important in exotic woods like Ipe, Cumaru, and Tigerwood.

Wood experts choose Ipe Oil™ because they know that wood penetration is the key to longevity and beauty.

CONCLUSION

We hope you’ve enjoyed our mini-science lesson on why wood turns grey. Make no mistake, the natural character of this process can truly be a standout feature of your home’s design. If you have any questions about any of the information in this article, please leave a comment below.