The first thing you should understand about carpet constructed of synthetic yarns – nylon, polyester, acrylic, polypropylene (Olefin)-is that they are solidified chemicals. In other words, when you apply spot cleaning agents to such carpeting, you are literally applying a chemical to a chemical. If a chemical reaction occurs, permanent yarn discoloration may result, which gives us our first rule in safe spot removal: Never use hard surface cleaning agents or laundry detergents on carpeting. Use only cleaning agents designed for carpet. However, if your carpeting is “stain-resist” nylon, even more restrictions apply. What makes “stain-resist” nylon an exception?
Nylon is superior to all other synthetic yarns, save for one respect: It’s more susceptible to permanent stains from fugitive (acid based) dyes. Since most food dyes are acidic; this single weakness can become significant especially in homes where people consume foodstuffs over carpeting. So, to help control nylon’s affinity for acid dyes, some fiber mills apply acid dye blocker to their nylon fibers. Nylon carpeting, so treated, is called “stain-resist” nylon.
What is dye blocker? Dye blocker is a colorless dye applied to nylon for the sole purpose of “plugging” the dye sites rendering the yarn far less susceptible to discoloration from foreign, acidic dyes. However, dye blocker is prone to yellow when high pH cleaners are applied.
What is pH? pH is a symbol for percent hydrogen. The pH scale is a rating system for measuring acid and alkaline strength: The pH scale is numbered from zero to fourteen and is divided in the middle. Seven, the center point, is neutral-neither acid nor alkaline-and is the equivalent of distilled water. A rating that falls below 7 is an acid; above, an alkaline. As the rating descends from neutral(7) to 6, 5, 4-the stronger the acid becomes, with “zero” being the strongest acid possible. As the rating ascends-8, 9, 10-the stronger the alkaline becomes, with “fourteen” being the strongest alkaline possible.
Because of dye blocker’s inclination to yellow when a strong, alkaline cleaner is applied, carpet and fiber mills do not recommend cleaners with a higher pH alkaline rating than 9. Some restrict the pH to 8.5.
How can I know what the pH is? Sometimes the pH is indicated on the container but most often not on consumer ready products. There are no laws requiring cleaning chemical manufacturers to indicate it. Avoid cleaners that don’t specify pH strength. They could exceed the pH limitations and turn the dye blocker yellow.
While there are a few acid cleaners around, most, by far, are alkaline, because alkaline cuts soil more efficiently. Further, when one considers the very wide variety of soils that accumulate in carpeting one can well imagine that chemical strength can influence soil cutting efficiency. Some cleaning chemical manufacturers will boost pH to increase efficiency, making the product unsafe for stain-resist nylon. Others will add bleaching agents which can also lead to problems with damage to carpet dyes.
Just be careful of what products you use to spot clean your carpets and pre-test before you ever need to use said products.