When cleaning carpets, it is important to know the type of carpet fiber and the type of soils present to choose the right chemistry for the job. One of the factors that affects carpets over time is the pH of your carpet cleaning chemicals. This determines how effectively the chemical can remove the spots or soils present, and can potentially damage carpet fibers in some cases. In addition to the pH, you should also consider the other ingredients in the product that can impact the carpet’s pH, which includes stabilizing solutions known as buffers.
How a High pH Affects Carpet
The pH scale ranges from 0-14, with 7 being neutral. A pH under 7 is more acidic, while a pH over 7 is more alkaline. Very alkaline carpet cleaners, meaning those with a pH of more than 9.0, can have an impact on carpet color. According to WoolSafe, high alkalinity can cause multi-colored patterns with multiple dyes and pigments to bleed, and natural wool fibers may yellow.
With wool, sisal, cotton, or jute-backed carpets, a high pH cleaner can worsen cellulosic browning, which causes brown spots to arise after cleaning.
When a carpet is repeatedly cleaned with high pH chemicals, a sticky residue is almost always left behind. These residues trap soil, hurting the carpet’s appearance and making it more difficult to clean. In some cases, the carpet will actually reach a pH as high as the chemical residue left behind limiting the release of soil during cleaning.
Stick With a pH Near Neutral or Slightly Acidic
Chemicals with very low and very high pH levels are corrosive and can even release toxic fumes into the air. Cleaners with a pH closer to neutral are safer for cleaning employees and building occupants
The Impact of Buffers
Although the overall pH is important, choosing a carpet cleaning solution solely on the basis of pH alone is not good enough. Carpet cleaning solutions include many ingredients, and these ingredients called buffers can contribute to raising or lowering the pH of your carpet over time.
Buffers are used to stabilize the pH of the carpet cleaning mixture. If, for example, that mixture has been buffered to a pH of 8 and is used on a carpet at pH 4, that mixture will cause the carpet pH to drift upwards and become more alkaline, eventually damaging the carpet. On the other hand, carpet cleaning solutions like our CRYSTAL DRY® EXTRA and CRYSTAL® QUICK RESTORE™ are largely unbuffered. The pH of carpet cleaned with these products will tend to drift downwards because the carpet is more highly buffered after dyeing than CRYSTAL DRY® EXTRA or CRYSTAL® QUICK RESTORE™.1
In order to protect your carpet appearance and your facility, stick with neutral or slightly acidic chemicals in the pH range of 5.0-9.0 and with few buffers like Whittaker’s Crystal® chemistry products.
1"The Wool Carpet Cleaner's Manual, Eric Brown, WoolSafe Organization.
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