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Proper Sorting, Soil Familiarity Critical to Laundry's Success in Removing Stains (Part 2 of 3)

In your experience, what are or have been the most stubborn stains to remove? What tips can you offer those of us who must contend with these most difficult substances that find their way onto and into our textiles?Chemicals SupplierSteven TinkerSteven, the director of research and development for Gurtler Industries, South Holland, Ill., has more than 30 years of experience in laundry chemistry research, development and marketing. He serves on the Textile Rental Services Assn. Healthcare Committee and the Uniform & Textile Service Assn. Plant Operations Committee.
A well-designed wash formula is set up to remove and minimize stains that are considered routine for a specific classification. The most difficult stains to remove are the “unexpected” stains.
Restaurant table linens are processed in wash formulas designed to remove food-based stains and cooking oils. And hospital patient textiles like sheets, towels and gowns are processed to make sure that blood, body oils and medicinal stains are removed. Mechanic uniforms are processed to most efficiently remove petroleum oils and greases and particulate soils or clays.
If an unexpected soil is present in one of these classifications, it may be difficult to fully remove. For example, dirty motor oil that shows up on a hotel towel or pillowcase may not be fully removed in the standard wash process. And the remaining stain can be “set” after washing and drying or pressing, making it even more difficult to remove in a subsequent rewash or reclaim process.
All this means that the sorting step is critical to make the overall wash process as effective as possible in stain removal. The better we sort, the more precise we can be in designing a specific wash formula to remove expected soils.
For example, in a hotel laundry operation, the sheets and pillowcases are often washed together because they are considered identical. However, pillowcases usually have a higher degree of soil from facial and hair oils and makeup stains that won’t be as prevalent on sheets. So, if the laundry separates sheets and pillowcases, two slightly different wash formulas can be designed to most efficiently remove the soils on each type of bed linen.
This way, we do not have to process the sheets in a harsher wash formula, as we would have to if the sheets and the pillowcases were washed together. With separate wash processes, we can save on water, energy and chemistry by using the heavier soil formula only on the pillowcases. And we get better stain removal on both classifications.
Even with thorough sorting and specially designed wash processes in place, some stains will occur. Sometimes you have to be a detective to identify a recurring stain source so you can develop a method to control it.
The worst stain to encounter, in my experience, is from a medicinal skin sanitizer used in hospitals. The common brand name is Hibiclens®. There are other brand names on the market; the chemical name to look for is chlorhexidine gluconate.
This material is used to sanitize a patient’s skin before an operation. Hibiclens has a distinctive pink color when it is fresh and unwashed. When washed in a regular process, the sanitizer appears to have been removed. But Hibiclens is unique in that when it contacts fabric, it chemically “binds” with the fibers and is nearly impossible to remove.
The problem is not readily visible because the residue is nearly colorless upon washing. The “invisible” stain becomes a big problem when it is exposed to chlorine bleach. It turns dark brown, and the reaction with the chlorine creates a permanent stain that has proven to be impossible to fully remove.
So what can be done? First, hospitals have explored using other topical skin sanitizers, like iodine-based products that are much easier to remove from textiles. Also, many hospitals or healthcare laundry operations have been forced to switch to oxygen-based bleaches to prevent the brown stains left by Hibiclens.
We have noted that a special prewash of textiles containing fresh Hibiclens in high-active reducing bleaches like thiosulfate can remove the stain prior to processing in a standard wash with chlorine bleach, but this method is not completely reliable. The best course is converting from chlorine to oxygen bleaching.
Another stain that is a problem, but is easier to remove, is any rust-based stain. Practically all soils encountered in institutional and commercial washing are either soluble in alkaline-based and surfactant-based detergents or can be broken down by bleaches for effective removal. But iron or rust stains are unaffected by alkalies, surfactants and bleaches. In fact, alkalies and bleaches make iron or rust harder to remove.
Strong acid washing can easily remove rust stains. The typical laundry operation identifies rust-stained items from its rewash or reject items by an orange-red color. Special rust-removing wash formulas are set up to use acid-based cleaners and reducing agents to dissolve the iron and remove it.
If there are high levels of iron in the laundry’s water supply, general yellowing of the textiles can be an ongoing problem that is hard to control. This is caused by the reaction of iron to alkaline detergents and bleaches. Many laundries faced with high levels of iron in their water turn to iron-removal units added to their water softeners to eliminate the problem before it affects the wash process.
Other substances that resist removal in standard processing are adhesives, waxes, ink, cement stains, metal stains and carbon-based stains like ashes or graphite. Many of these stains can be attributed to misuse or abuse of the textiles. A good training program for your customers or end users is essential to eliminate these stubborn stains before they are created.
The more you know about the soils you expect to encounter in your operation, the better you can be prepared to address them. Work with your chemical supplier to design the best combination of sorting classifications and wash processes. Proper investigative work to identify the source of “unexpected” soil can help you treat or eliminate those problems.

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