The pH paper is either dipped in the sample or a drop of the sample is placed on the paper. The color of the pH paper changes immediately, and it can then be compared with the colors of the chart.
The pH paper is not made to be used more than once. Do not reuse the same strip of paper, because your results will not be accurate.
PH paper can contain a mixture of different reagents. Sometimes these reagents are mixed in the paper, while in other cases they are separated in several strips, with each strip containing a different chemical compound.
It is not necessary to use a large piece of pH paper to perform a test. A small piece, one that can be grabbed between your thumb and index finger, will suffice.
Take note of the pH value you obtained immediately after you do the test. Do not keep the pH paper as a record of your test, because colors will change with time.