Coffee stains, juice spills, overturned soda cans: When it comes to carpet cleaning, these can be a custodian’s worst nightmare — and a source of frustration when spots reappear weeks after being treated. These repeat offenders are often the result of soil wicking, a challenge in any carpet maintenance program.

Soil wicking occurs when water and detergent move upward from the base of the carpet to the tips of the fibers during the drying process, carrying with them embedded soil that is then deposited on the carpet’s surface. 

During carpet care training classes, Bill Yeadon, senior instructor at Jon-Don, Roselle, Ill., illustrates the concept of wicking with the following demonstration: “I take a water pitcher and put a couple of ounces of Coke or coffee in it,” he says. “Then I take a roll of paper towels and put it in the pitcher. The moisture wicks up the paper towels and takes out everything in that pitcher. That’s what’s happening anytime you have carpet fibers. The moisture has to wick to get out of the carpet. The water will evaporate, but the coffee, dirt, and sugars will not, so they’re left on the surface of the carpet. It’s a real problem.”

Overuse of chemicals and water can exacerbate soil wicking, which is why proper spot removal and carpet cleaning methods are so important.

“If you have wicking problems, your carpet will have a grey tint to it,” says Kevin Thompson, sales manager for Brookmeade Hardware and Supply, Nashville, Tenn. “That’s telling you there’s a buildup of chemical in it. If you looked at the tips of the carpet under a microscope, they would be brown, which is caused by overuse of chemicals.”

Operator error is often to blame for excess detergent and water when cleaning carpet, as well as their improper removal after cleaning. Throw in insufficient vacuuming and custodial managers have a recipe for soil wicking disasters.

“Almost 80 percent of all soil is dry,” says Yeadon. “With hot water extraction, a lot of that dirt sitting in the carpet turns to mud, so the first principal of cleaning is always vacuuming.”

Spot On

While soil wicking can have an effect on the entire carpet, experts agree that recurring spots and stains are the most visible and troublesome results of wicking.

“In commercial buildings people care about spots,” says Yeadon. “If the carpet was cleaned last night and someone came in the next morning and spilled their coffee, what you see is the spot.”

And while it may appear that the carpet is clean after removing the spot, if not done properly, that coffee spill can come back time and again.

“On the surface it’s gone, but when that coffee was spilled, it went down to the backing of the carpet and spread out,” explains Yeadon. “As it dries, all that coffee mixes with the dirt that’s down there, which gives that big splotchy effect called wicking.”

To help prevent soil wicking, distributors stress that managers provide their cleaning staff with the right type of chemical to address stains and spills.

“The biggest mistake people make is using the wrong product,” says Thompson. He recommends starting with a solvent-based product before a water-based product, if cleaners don’t know what the stain is. Using the wrong product can actually set a stain.

Distributors also warn customers not to rub the stain but rather blot it with a towel.

“The common misconception is you take a spotter, apply it to the spot, rub the spot and it goes away,” says Yeadon. “But all you did was push it down further into the carpet.”

Thompson concurs: “Don’t rub it back and forth because you spread the stain out,” he says. “Take a damp towel and stand on it, or if you’re using an extractor you can use the hand tool to vacuum over it.”

Low-moisture carpet cleaning methods, such as encapsulation, are also successful in treating spots and preventing soil wicking. Once applied to the carpeting, the encapsulation chemical crystallizes around the soil on the surface and can be removed.

“The moisture’s not penetrating down to that primary backing, so it doesn’t reactivate those coffee spills and dirt, and it dries quickly so there’s no wicking,” explains Yeadon.

Absorbent compounds are also an effective low-moisture carpet cleaning method that can help prevent wicking. Impregnated with small amounts of water, solvents and cleaning detergents, these granular compounds are sprinkled onto or worked into the carpet with a machine and then vacuumed up.

Because this is considered a low-moisture cleaning method, wicking is unlikely to occur; however, there is still the potential to overuse the chemical. In fact, distributors agree that all too often workers apply too much absorbent compounds.

“Using excess will require longer dry times and makes vacuuming difficult,” says Clint Mervicker, national customer partner for VCP International Inc., Garland, Texas. “Often, product is still going to be [in the carpet], and if you don’t get rid of it, it will attract dirt.”

KASSANDRA KANIA is a freelance writer based in Charlotte, N.C.

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Deep Cleaning Carpets Can Minimize Wicking