ABBEY Pen pH test pen

Pen for randomly checking the pH value of paper, cardboard and paperboard.

The pH indicator used is chlorophenol red.

This is how it works:

• Mark the test material with a line and observe the color change.

• If the marking is light yellow, the material contains acid, the colour beige indicates a medium acid content, and if it is light purple, the material is neutral or alkaline.
• For archiving photographic materials, the materials used should ideally be neutral or slightly alkaline.