The Abbey pH testing pen was developed over 15 years ago by Ellen McCrady as a simple tool to easily and instantly spot test books, documents, paper and card for acidity. Using chlorophenol red as the pH indicator agent because it provides a consistent colour response to a given pH level regardless of the concentration of the agent found in the pen's nib. Some other products are not as accurate when the agent concentration is variable.
This formulation of chlorophenol red therefore provides very accurate and reliable test results. It is used by archivists, librarians and conservationists to identify acidic or alkaline paper.
Another major benefit of this pH testing pen over other pH pens is that the lighter shade of the line or spot makes the test as inconspicuous as possible.
We have even supplied these to
the British Museum in London!
The acid content in paper determines its life expectancy. The acid content is measured on a pH scale:
- pH 3-6 very acidic with a short life expectancy
- pH 7 neutral and classed as acid free - lasts 200 years
- pH 14 alkaline with a very long life expectancy - 500 years or more
Acid free paper (pH 7.0 and above) has a high degree of durability and permanence and will last for up to 200 years under normal use and storage conditions. It will not discolour or become brittle with normal handling.
How to use the Abbey pH testing pen:
Draw a small line or place a spot in an unobtrusive area of the material being tested. Dries in seconds.
If the result indicates pale yellow (below 6.5), the paper is acidic.
If the result indicates pale purple, (above 6.8) the paper is neutral or alkaline. This is the result required for long term conservation.
If the result indicates a tan colour (combining yellow and purple) the paper is of intermediate acidity.
Please note: unreliable results may occur on coloured or coated paper. | 
