Question: Why are certain (carpet) cleaning agents buffered and others are not? What, in your opinion, is the role of a buffer in cleaning chemicals? Is it:
- to stabilize the pH to enhance the cleaning power of the chemical;
- to stabilize the pH to improve the shelf life of the chemical;
Answer from Jeff Bishop, SCRT Technical Director:I’m not a chemist, so this is a better question for someone like Dr. Al Luedtke but my impression is that buffers both stabilize pH to make the cleaning detergent more reliable, and also less subject to factors that might affect detergent performance. For example, a product built with volatile ammonia, for example, might not have as long a shelf-life as a buffered product built with STP or TSP.
- to change the pH of the material to be cleaned so it cleans better;
When the pH of a material, such as carpet or upholstery fabric, is high or low (normal pH of wool fiber is between 3 and 5), it can affect the performance of a cleaning chemical. Further, if there is a chemical residue in a carpet, that also can affect the pH and performance of a cleaner. Thus, the need for buffering.
Changing the pH of a carpet or other material really isn't the issue. It’s the soil suspension process that’s enhanced with judicious use of built products. In fact, if the pH of wool or cellulosic fiber is changed, browning, dye migration or fiber degradation can be an issue. That’s why WoolSafe specifies no built products.
The problem with buffered products is that the pH can’t be changed significantly. As they dry, they tend to concentrate, and, as you know, the strength of a solution is really a function of both pH and concentration. During that drying process, the buffered and concentrated pH acts on dyes and fibers to cause migration or deterioration. Not good. Moreover, there is no way to neutralize a built product with an acid rinse.
Personally, I prefer non-buffered products, such as those approved by the WoolSafe Organisation in England. They give me the ability to move the pH up, or more often, down the scale, especially when neutralizing alkalinity, minimizing the incidence of browning, controlling dye migration, or preventing fiber degradation.
Again, I yield to Dr. Luedtke’s far superior knowledge in this area.
Comment from Dr. Al Lueftke
Your comments well capture the key elements in address this person’s questions. It’s my view that the chemistries functioning as buffers contribute a variety of attributes to the cleaning product and the extent of their role (or their need) in any one area depends a fair amount on the characteristics of the surfactant system employed and what you want the product to do.
