Red cedar is one of the most popular wood species for exterior use because of its natural rich, red color and its natural resistance to decay.
But one aspect is that cedar's lovely red turns a monotonous gray surprisingly quickly. Once cedar has turned gray, there is no natural way of going back. The only alternative at this point is to tone the wood with a stain or other coloring agent.
Maintaining your cedar's color is about choices, timing, and above all, the right type of treatment. To fully understand the best way to stain or treat cedar, you first need to understand the nuances of this unique wood's weathering process.
How Cedar Wood Weathers
Western Red Cedar grows to 200 to 250 feet tall and lives for very long, often centuries. One cedar tree in Idaho has even been dated back to the time of the ancient Egyptians: about 3,000 years old. With that kind of longevity, it's no wonder that cedar works well as a long-lasting, durable building material, too.
Cedar wood deteriorates slowly due to its abundance of the natural oils cedrine, cedrol, and thujopsene. So beneficial are these oils, they even have medicinal properties to treat inflammation and fungus.
From a structural standpoint, cedar more than holds its own. Untreated cedar fences can go for many years before they need to be replaced.
Although weathering begins immediately with cedar, it quickly slows to a crawl. Weathering quickly progresses into the wood to about 2 mm before it slows down. But over time, the weathered portion of the wood begins to splinter or flake away, exposing fresh wood to the elements.
Should You Leave Cedar Untreated?
One oft-mentioned selling point of cedar is that you can treat it with oils, stains, or paints—or let it weather on its own. Some owners like this look, while others may think that it looks tired.
When fully weathered, cedar takes on a light silvery-gray appearance. If you like the weather-beaten look of a seaside cottage or an old barn, cedar can develop that look all on its own.
But one aspect of cedar's weathering process that doesn't appeal to some homeowners is that it turns gray unevenly and looks blotchy. While this process is not apparent over small areas, it is noticeable when you are looking at wide expanses, such as siding. This effect is even more pronounced between different sides of the house, where the siding may experience sun, wind, or precipitation at different rates.
Unless you particularly want untreated cedar wood, it's best to treat it. Cedar fences should be treated once a year. Cedar's natural oils do protect the wood, but only for a finite period. Eventually, decay will start to set in. When the cedar becomes too porous and splintery, it's more difficult to treat effectively.
Attractive silver-gray color
Eventually leads to decay
Silver-gray turns more gray with time
Cedar Treatment Basics
When treating cedar, the most vital question is: how much of the real wood do you want to cover up? Do you like the natural but weathered look of cedar? Or do you prefer an even but unnatural look?
After installing your exterior cedar, make sure to begin treatment before the wood starts to discolor. After that, the color will rapidly change from red to silvery-gray.
If you do decide to color your wood, there are several options. Most cedar treatments are much like house paint in that they are composed of pigments and solids. The more solids in the treatment, the longer the cedar will last.
Treating Cedar With a Bleaching Oil
If you want the gray, weathered appearance of naturally aged wood, but also want protection, you will need to take special efforts to make it look natural. Applying bleaching oil is a two-step process.
First, the oil tones the wood with a light gray pigment to fix and stabilize the color. Second, over a short period of time, the oil will accelerate the bleaching process so that you get the weathered look faster and with more uniform results.
The fully uniform weathered effect, though, will take between three and six months to develop. Cabot Bleaching Oil is one prominent brand of oil appropriate for artificially weathering cedar.
Best if you like the look of weathered cedar
Does not change look of the cedar much
Staining Cedar With a Semi-Transparent Stain
Semi-transparent stains are your best bet when you want the real look of slightly weathered cedar with protection. The few solid particles in this mix will not significantly obscure cedar's wood grain.
However, with semi-transparent stains, you will need to take care with the application. Manual brushing is often the best option since spraying can result in blotching. Semi-transparent stain also beads up water, preventing moisture from penetrating the wood's cellular structure.
Semi-transparent stain on cedar will cover up some minor imperfections and blotchiness. But dark stains, like rust or paint, will show through.
Lets wood grain show through
Can blotch if not applied correctly
Not a cover-up
Staining Cedar With a Solid Color Stain
Solid color stains have solid particles, but not nearly as many as paint. Thus, solid color stains let some of the cedar's grain show through, but none of the color. What you get is a very uniform opaque color. The upside is that solid color stains will block most of the damaging ultraviolet light. Plus, this type of stain is excellent at repelling water.
Solid color stain is as close as you can get to applying acrylic-latex paint to the fence, without actually using paint.
Blocks UV rays
Covers difficult stains
Little of the grain shows through
Looks much like paint
Treating Cedar With Primer and Paint
If protecting a deck, then painting is your best option for treating cedar. Paint's solids ward off light, and light is the main contributor to the deterioration of cedar. Lighter colors last longer since they reflect light more efficiently than darker colors.
When you have a cedar fence that is very deteriorated, patching it and painting it with exterior-grade acrylic latex paint just might save it.
But be aware that it is notoriously difficult to mimic authentic wood color with paint. If you absolutely want some type of wood appearance, paint is not a good alternative. Because of cedar's large pores, it is necessary to prime the wood before painting it.
Can save an extremely weathered fence
Obliterates the appearance of wood
Frequent reapplication may be required
Red cedar dust can cause breathing problems or exacerbate the condition in people who already suffer from asthma. Volatile compounds within the wood have been identified with this condition. When sawing, sanding, planing, or undertaking other activities with western red cedar, be sure to use a twin cartridge respirator, not a paper mask.
Jeong, Hyeon-Uk, et al. Inhibitory Effects of Cedrol, β-Cedrene, and Thujopsene on Cytochrome P450 Enzyme Activities in Human Liver Microsomes. Journal of Toxicology and Environmental Health, Part A, vol. 77, no. 22–24, 2014, pp. 1522–32. Taylor and Francis+NEJM, doi:10.1080/15287394.2014.955906
Yang, Chen Xi, et al. Diagnosis of Western Red Cedar Asthma Using a Blood-Based Gene Expression Biomarker Panel. American Journal of Respiratory and Critical Care Medicine, vol. 196, no. 12, 2017, pp. 1615–17. atsjournals.org (Atypon), doi:10.1164/rccm.201608-1740LE