pH Measurement and Meters
July 12, 2007
It has been a few years, but I can still remember when my parents gave me my “Junior Scientist” chemistry set. It included both red and blue litmus paper that would change color when dipped in various solutions. Neat! It was my introduction to the principles of pH balance, knowledge I’d be using for the rest of my life.
With the passage of time came progress. By the time I attended my first carpet-cleaning class, you only needed a single roll of pH paper to perform the same tests that had required two kinds of litmus paper. I had a great time checking out the pH of my current cleaning solutions. Things began to click and I started to realize why different solutions worked better on different soils.
No longer limited to creating vinegar and baking soda volcanoes, I found more constructive uses for pH paper and acid/base (alkaline) reactions. Checking the pH of a spot or stain helped me decide on the most effective way to remove that stain. Neat! Acid stains were best neutralized and removed with an alkaline cleaner. Alkaline stains could be made to disappear with an acid-side spotter.
With experience and further training, a pH reading proved helpful in identifying the sources of various stains. Customers were pleased that not only could the stain be removed, but I could educate them on how to avoid future stains. I remember feeling warm, fuzzy, and pretty smart when I checked out the dark spot on the carpet and told the customer that, based on an alkaline residue, foam, and the slick feel (builders) when wet with water, I believed her spot was attracting soil because of residue left from some type of alkaline cleaner. She blamed it on the previous cleaner, but for all I know her husband tried to clean out a chili-dog spill with his engine degreaser from the garage.
Of course, pH paper did have its drawbacks. If your fingers touched the paper strip it could alter the reading, reducing your chance of success on the spot and your finger tips looked like you had gotten into the cheese puffs. Color from the strip could also transfer to the carpet and add to the problem you were seeking to correct.
Cleaners needed to be sure the pH strips were fresh. With age and exposure to humidity, the accuracy could degrade. If the roll of pH paper had been open for a while, you would need to be prepared to purchase a new package.
It was hard to tell the difference between a reading of 4 and 5, and forget being able to distinguish between 5.0 and 5.5. If you suffered from any form of color blindness, efforts based on your interpretation of the strip could make the problem worse.
Electronic pH meters were first introduced to our industry more than a decade ago. These meters eliminated many of the problems with standard pH paper, but few could afford or justify the expense. Over the last few years, prices have tumbled while precision, accuracy, and ease of use have increased.
Older style pH meters required the staining material be dissolved in water before being tested. So the cleaner would use his bone scraper or a spatula to remove some of the staining material. This needed to be transferred to a small container and mixed with water before taking a reading.
Current models of the pH pen only require the spot to be damp. Then you just touch the tip of the meter to the stain. After several seconds the meter displays a digital reading. They’re more accurate and they save you time compared with taking a reading the old-fashioned way. With a three-point calibration, you can get a reading correct to .01. Neat!
Of course, this is more accuracy than a cleaner needs. But for those of us raised with a “Junior Scientist” chemistry set, and for other anal-retentive types, it is nice to know you can get such accuracy. The additional accuracy is also welcomed by carpet inspectors, whose work often requires precision.
Your customer (or prospect) points out a spot on her carpet that concerns her. You kneel down nearby, pull your pH pen-type meter from your shirt pocket and proceed to analyze her stain. What a professional image you have presented. A positive moment of truth that builds her confidence in your ability not only to remove this spot, but to thoroughly clean all the carpet and furnishings in her home.
A quality pen-style pH meter now costs about what half a dozen rolls of pH paper would cost. Given all the technical value and marketing value for this meter, isn’t it time you moved up to the “Senior” chemistry kit? Neat!