pH (potential for Hydrogen)

A measurement of the acidity or alkalinity of a solution or material. The pH scale runs from 0 to 14, with pure water being neutral at 7.0. Less than 7 is acidic, over 7 is alkaline. The pH scale is logarithmic, where the difference between pH 7.0 and pH 8.0 is ten-fold, and the difference between pH 7.0 and pH 9.0 is a hundred-fold. Typical litho fountain solutions are moderately acidic, being between 4.0 and 5.5 pH.