The Secret to Soft Linens

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Created on Saturday, 02 July 2005 17:10

Written by Matt Heisey, Senior Scientist – Procter & Gamble

Since we were kids, we’ve been taught the benefits of getting plenty of calcium. But the same mineral that helps us build strong bones and teeth can have a less than desirable effect when it builds up on hotel linens (sheets and towels). In a process called encrustation, calcium deposits can leave towels and sheets feeling stiff and scratchy, which may have a potentially detrimental effect on guest satisfaction.

But before general managers or executive housekeepers can figure out a way to reduce encrustation, it’s important to first understand exactly what it is and how it’s caused.

Calcium is found naturally in water. The national average is about six or seven grains of calcium per gallon of water, but in some hard water areas the amount can be as high as 25 grains or more per gallon. Under the right conditions, the calcium can deposit on fabrics in the wash cycle causing encrustation, which over time can leave the fabric feeling rough to the touch.

Calcium (measured as Calcium Carbonate) is dissolved in regular pH neutral water. If the pH level of the water increases, the calcium becomes less soluble, increasing the likelihood of its being deposited onto the fabric. Increasing the water’s pH levels (a.k.a. increasing alkalinity) is the way many institutional and industrial laundry detergents work to get items clean. As the water’s alkalinity increases, the fibers of the fabric swell, allowing the dirt to release. Later in the process, another chemical releases sours (acids) into the water to bring the pH balance back to neutral and the fibers shrink to normal.

Theoretically, once the water is back to neutral, the calcium should dissolve again. But, as is often the case, the calcium has already deposited onto the fabric or the laundry chemicals don’t add enough sour to the water to force it to dissolve. This can be even more of a problem for hotels with hard water conditions that fail to use water softeners, since hard water contains more calcium.

To attempt to alleviate the calcium concern, several institutional and industrial laundry detergents include other ingredients, called builders, to help trap calcium in the wash water. This approach is not always successful. If there are insufficient or inefficient builders in the detergent, calcium will remain in the wash water allowing for encrustation. In addition, calcium that is allowed to remain in the wash water can negatively affect the surfactants making them less efficient toward cleaning.

Unfortunately, getting rid of encrustation is not as simple as just washing off the calcium deposits. Once encrustation forms, it’s unlikely that it can be removed entirely with normal processing. What hoteliers can do, however, is prevent any future buildup.

Besides softening the water you use in your laundry, the best way to prevent or reduce encrustation is to keep the wash water’s pH levels near neutral. There are some laundry products on the market that are pH neutral – just like water. Since they don’t significantly alter the alkalinity of the water, the calcium remains dissolved and can’t build up on fabric. Just this process alone will help to make towels and sheets less stiff, but adding a fabric softener to the wash cycle will add additional softness as well as a fresh, pleasant smell.

As more guests seek out hotels that offer the amenities of home, the importance of soft towels and sheets increases dramatically. Selecting laundry products that work for you rather than against you is an easy way for hotels of any size to protect their significant investment.

Matt Heisey is a Senior Scientist in Laundry Product Development for Procter & Gamble’s Commercial Products Group.