The term pH refers to the negative logarithmic concentration of the positive hydrogen ion (H+). The “p” stands for potential or power like power of ten, which an exponent, in this case a logarithm. The “H” stands for H+, which really has reference to the hydronium ion (H3O+) formed by an H+ combining with H2O.
Using a pH pencil gives you a way of measuring the acid concentration of the base surface with the term "acid" referring to a compound that lowers the pH of the solution by donating a hydrogen ion/proton (H+), and the term "base" referring to a substance that accepts a hydrogen ion/ proton (H+).
These pencils can be used to measure the pH of...
Any surface, be it porous material or impervious solids, pH pencils will give you an accurate reading of the surface pH.
Please note: The water you use MUST BE DISTILLED WATER! Not tap water, not spring water, not bottled water... only use distilled water available at most grocery and hardware stores.
To measure the surface pH..