Outdoor wood furniture can take a beating from the elements throughout the year. As such, it should be cleaned more than once in a year, especially at the beginning and end of the warm season when it gets the most use. This will not only get rid of any dirt and grime, but also mold and mildew that might have started to grow. Cleaning can even prevent future mold growth that will threaten the life span of your furniture. Follow these guidelines for removing harmful spores so your wooden chairs and benches can look great and last.
Safety note: When cleaning, never mix chlorine bleach with ammonia-based cleaners, as it creates a dangerous chlorine gas.
Step 1 - Dry Out Furniture Before Cleaning
Since mold is caused by too much moisture, there’s a good chance mold-infested wood will be damp. Dry it out by sitting it in direct sunlight for several hours before starting to clean.
Expensive or antique furniture may need to be treated by professionals after you've let the wood dry, especially if the mold and mildew growth is extensive.
Step 2 - Prepare Area and Cleaner
Bleach can damage plants and poison small animals, so find a place to clean your furniture (like on concrete or on top of a tarp) that won’t kill vegetation or pets. Also, keep pets and small children inside while cleaning; smaller, younger animals and humans are especially susceptible to chemical products.
Mix up a cleaning solution of water, bleach, and dish soap or detergent that is about 10 percent bleach and 90 percent water with several drops of the soap. If you prefer not to use beach, rubbing alcohol can be substituted instead. Rubbing alcohol and water should be mixed 50/50 before adding the several drops of soap.
Step 3 - Dry Scrub
Before getting the furniture wet, scrub the surface down with a dry scrub brush first. Don’t forget to work the underside of the furniture since the underside rarely gets sunlight and is more susceptible to mold. The dry scrubbing will get rid of any debris and dirt before cleaning so it’s easier to see the mold, and so that the dirt and debris isn’t rubbed into the furniture.
Make sure to wear a face mask during this process. Although you will be working outside where there is plenty of ventilation, mold spores will be scattered into the air during dry scrubbing and it is best that you don't inhale them.
Step 4 - Rinse with Water
Rinse down the wood using a garden hose with attached nozzle or pressure washer on a low setting to remove the mold particles that have been rubbed off with the dry brush. Don’t forget to rinse the undersides as well.
Step 5 - Scrub with Bleach Mixture
If dealing with painted wooden furniture, fill a spray bottle with the bleach or alcohol solution, and spray it down from top to bottom and on the underside as well. Scrub the cleaner in lightly or use a sponge so that the paint doesn’t begin to chip. For unpainted furniture, scrub heavily, dipping the brush in the bleach, water, and soap mixture as needed.
Step 6 - Rinse and Dry
Hose off your furniture once more and inspect the surface. Repeat scrubbing down if any mold or mildew still remain. After all the mold has been removed, leave the wood out in the sun to dry completely before placing it back in position.
Tips for Maintaining Outdoor Wooden Furniture
Besides cleaning, there are other steps you can take to ensure the longevity of your deck or garden furniture. Most importantly, always store wooden furniture pieces in a dry place during the winter or rainy months. This will protect the wood from a lot of the moisture that actually causes mold growth.
Also, make sure to keep any wooden furniture pieces properly sealed for outdoor use. Sealer isn't completely permanent, so if it's been awhile since your furniture was treated, take some time to do it again.