An understanding of pH can put a stop to costly mistakes
January 1st 2006

Measuring pH and understanding what chemical to use on a particular carpet can reduce the potential for damaging carpets. But what is the best way to get a reliable measurement of pH? Extech Instruments developed a meter that is able to have direct contact with the carpet and give accurate results

The process of carpet fibre analysis and cleaning, in both residential and commercial applications, has grown more scientific, relying more heavily on advanced methods and sophisticated cleaning agents to remove dirt, spills and stains. Because of the complex fabrics being used in today's floor coverings, as well as their highly developed stain-resistant properties, the process of cleaning and restoring carpets has become more of a science. The growth of the scientific side of this business has occurred for two reasons:

• To reduce the potential damage that can arise from using improper cleaning methods or materials.

• To reduce the corresponding liability of commercial carpet cleaners and to a growing degree, residential carpet cleaners.

At the heart of this push is the use of pH analysis as a guide toward more efficient cleaning methods. pH is a unit of measure, ranging from 0 to 14, that indicates the degree of acidity or alkalinity of a solution. Solutions with a pH less than 7 are considered acidic, solutions with a pH higher than 7 are known as bases, and solutions with a pH of exactly 7 are neutral.

With this explanation as a backdrop, it is easier to understand why the selection of cleaning or restorative chemicals is pH dependent. If the pH of the cleaning or restoration chemicals is not in the correct range, they can seriously or even irreparably damage the carpet.

Consider: If the pH of a carpet fibre is 10 or 11, meaning that it is 'basic' - cleaning personnel will not want to select a highly alkaline or basic chemical to treat it. An acidic detergent should be used to neutralize the stain. What's more, stain-resistant treatments on carpeting can be removed if the pH is too high during and after cleaning and wool carpet dyes could start to bleed if the pH rises over 7.0 during the cleaning process.

With the value of pH measurement now firmly established, all that remains is the identification of an effective pH testing method. The market now offers a wide spectrum of sophisticated pH meters that are affordable, accurate and easy to use. In the early years it was either the bulb-type pH meter or pH paper that was employed, yet each had certain disadvantages, particularly for carpets. The bulb-type pH meter was ill-suited for a smooth carpet; it is only truly functional for carpets where the user can actually get the bulb surrounded by carpet fibre - as with shag, for instance. The shortcomings of pH paper are inaccuracy and potential carpet staining.

What the industry needed was a pH meter with a surface that could make good, solid contact with carpet fibre, yet was far more durable than the glass bulb. Consequently, about three years ago, Extech Instruments decided to invest in developing its own pocket-sized, stick-style series of water quality meters incorporating a flat surface electrode module. The result was the Waterproof ExStik pH Meter.

The ExStik pH Meter offers 1-, 2- or 3-point calibration and features a built-in smart chip that offers advanced functions and features not found in any other pH stick meter. From a straight liquid application, there are stick meters available that are equally accurate. However, the major advantage of the ExStik is its flat surface electrode, a design not incorporated into any other stick-style pH meter. Having the ability to make direct contact between the electrode surface and the material being measured presents a huge benefit when measuring pH. There are several companies that produce stick-style meters with the traditional glass bulb electrode, but Extech is the only one with the flat surface electrode.

This flat surface also makes the ExStik more durable than bulb-type meters, as there is minimal breakage. Additionally, the replacement modules are less expensive. Furthermore, the ExStik is infinitely more accurate than pH paper. The ExStik automatically tells the user through an on-screen message when it's time to re-calibrate and when it's time to replace the electrode. No competitive products on the market today have these capabilities, nor do they feature memory, which allows the ExStik to retain multiple data points.

Without question, the emergence of pH as a significant test has radically changed the way carpet cleaning is performed. What's just as clear is that an accurate, portable and highly functional pH meter like Extech's ExStik is critical in ensuring that the science side of this process is well represented.