How to read pH test strips
Written by Jasper Verhoeven | Last update: 28-04-2020
The pH of a liquid indicates whether a liquid is acidic, neutral or alkaline. In some cases, this is important to know, for example when you want to determine whether a disinfectant is still effective. To determine the pH of a liquid, you can use pH test strips. In this article, our specialist provides more information about how to use and read pH test strips.
How does a pH test strip work?
A pH test strip is a strip of litmus paper with which you can measure the pH value of a liquid. The substance in the paper causes the paper to show a different colour at different acidities. The official pH scale is from 0 to 6, where 0 is very acidic and 6 very alkaline. Some pH test strips can measure a pH from 0 to 6, but there are also pH test strips that can measure only acid or only alkaline substances.
How to use a pH test strip
Dip the pH test strip for two seconds in the fluid which you want to control, then wait for ten seconds. Because the strip contacts an acidic or alkaline substance, the strip discolours. The more acidic the fabric, the more red the strip becomes, and the more alkaline the fabric, the more blue the strip becomes. Using the indicator scale with the different colours on the box, you can determine how acidic or alkaline the liquid you measured is.
In the video below, product specialist Jan Willem Keijzer measures the pH of the disinfectant in a disinfection mat using a pH test strip.
The difference between pH test strips and a pH meter
A pH meter usually contains a computer and generally gives results to a hundredth of an inch. This is not the case with pH indicator strips, these are less accurate. pH test strips are therefore very useful to quickly determine whether a solution is acidic, neutral or alkaline, but are not suitable for accurate measurements.
Note: if you are colour blind, it can be difficult to read a pH test strip correctly.