How to clean moldy outdoor furniture straps

A: Jim Kaufman is owner of Criterion (800-422-8360; criterionrepair.com), a company in Keyser, W.Va., that cleans and repairs outdoor furniture for homeowners and resorts in a wide area around D.C. He looked at the pictures you sent and said your chairs look like Brown Jordan pieces with Suncloth straps — as you confirmed in a follow-up call.

You are correct in saying the company offers scant cleaning instructions on its website, brownjordan.com. The focus is on available colors and furniture collections, with very general cleaning instructions. “Wash the furniture with a solution of mild detergent and water, rinse with clear water, and dry thoroughly,” it says. It recommends coating metal frames with a “fine, clear automobile wax for maximum protection against harmful ultraviolet exposure and salt air.”

There is also a bit more detail about cleaning fabrics: “Mildew and heavy stains can be removed with a quality commercial outdoor furniture cleaner and protectant.” But that section seems to pertain to cushions, not straps.

Brown Jordan recommends cleaning its outdoor furniture two to three times a year in low-pollution areas and more often in areas with greater pollution. Kaufman said that in a heavily shaded garden like yours, especially where the air is damp for long periods, frequent cleaning is essential. When that doesn’t happen, the straps can become severely stained, even if the furniture is stored indoors for winter.

Suncloth feels more like cloth than the vinyl webbing that’s usually used in outdoor furniture. That makes it a more high-end feature — but one that seems to be more prone to harboring algae than vinyl webbing is, Kaufman said. Introduced in 2012, it was developed by Brown Jordan and Sunbrella, which makes acrylic fabrics that stand up to outdoor use. Suncloth is 100 percent acrylic, a Brown Jordan customer service representative said. But the straps aren’t just thin strips of Sunbrella; they stretch more, which helps make the chairs more comfortable.

Regardless of whether the straps are vinyl or Suncloth, Kaufman said, cleaning with a mild detergent might work if the pieces are cleaned frequently. But once stains develop, this is usually not enough. He suggested running your finger over the straps to determine whether the white specks stand out from the strap material. If so, those might be lichen, a type of symbiotic growth that consists of a fungus that provides the structure for the algae or cyanobacteria living within it. If the specks don’t have a noticeable texture, you’re probably seeing stains from mildew. (The terms mold and mildew are often used interchangeably. Both words refer to types of fungi.)

If you detect lichen, you might be able to brush off much of it. But to remove any remaining stains — or stains from mildew — use a more powerful cleaner. A customer service representative at Brown Jordan said some customers have reported getting good results by using Zep or OxiClean. A Zep representative said that brand’s most suitable cleaner is Fast 505 industrial cleaner ($4.89 for 32 ounces at Home Depot). OxiClean’s versatile stain remover is $7.59 for a 1.77-pound tub at Ace Hardware.

However, the Brown Jordan representative said the homemade cleaning formula that Kaufman recommended should also work and would be safe to use on the straps. Kaufman suggested mixing hand dishwashing detergent, such as original Dawn, with water and chlorine bleach. Start with ¼ cup of chlorine bleach to 1 gallon of water, then, if needed, clean a second time with a stronger solution of up to 1 cup of bleach per gallon of water. (Using hand dishwashing detergent with bleach is safe, but never combine a bleach solution with any cleaning product that contains ammonia, because that would release a toxic gas.)

Whatever cleaner you use, work outside, so you can rinse the chairs thoroughly with a hose. If the bleach or cleaner might get on landscaping, dampen the plants first to help dilute spatters. Put on goggles and rubber gloves, and, if you’re using bleach, wear clothes you don’t mind getting spattered.

Even after cleaning a second time, some stains might remain, Kaufman said. In that case, your only options would be to live with the stains or have the webbing replaced with either vinyl or Suncloth straps. A vinyl redo would cost about $100 a chair for materials and labor, Kaufman said; Suncloth straps might double the cost, because he can only buy the material in large quantities.

Installing either material takes about the same time, although the process is a little different. Vinyl straps must be heated, so they stretch while they’re installed, while Suncloth straps need to be stretched by being pulled, Kaufman said. After installation, both materials shrink to their original length but stay stretchy, which makes the chairs comfortable to sit on.

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