The Hydrion pH test pencil measures the pH of any surface, usable almost anywhere. Handy for spot checks on solid or porous material and surfaces to be painted such as drywall or concrete block. Also useful to determine pH of a cosmetic product on skin.
First, wet the surface or area with distilled water. Stroke the surface several times with the pH pencil. After 30 seconds compare resulting color with the color chart. Contents of tap water can distort the result, so use distilled water.
Pack contains 3 pencils, 3 color charts and directions.