Hi Chelsea,
Yes it is good practice to periodically refresh the chemicals used for testing. But there are also a couple other reasons you may be getting the results from your Abbey Pen that you describe.
In the 1990s paper mills broadly moved from an acidic manufacturing process to an alkaline process. They moved away from the old alum rosin sizing (acidic) and substituted newer neutral or alkaline sizes. Even more significantly they began loading paper with synthesized calcium carbonate. The highly alkaline calcium carbonate is cheaper than fiber, so it makes sense for the paper manufacturer to use as much as possible in the mix. It also imparts opacity to the paper (making it possible to print both sides even on a thinner paper) and contributes to a smooth surface for crisp printing. Today I find it difficult to find a common office or printing paper--book paper, printer paper, sticky notes, envelopes--that does
not test alkaline because of the heavy calcium carbonate loading. Even boxboard and other products made from recycled paper often test alkaline if they are made from recycled papers loaded with calcium carbonate.
Another point to be aware of, there is often enough calcium carbonate on the paper to brush off onto the tip of the Abbey Pen. That means that if you test a paper that is heavily loaded with calcium carbonate then immediately test another paper that is not, you may still get an initial purple (alkaline) reading. I've learned to always wait a minute or two and watch to see if the color changes as it sits on the paper. If leaving marks on the paper doesn't matter, I might rub the tip a few time to dislodge any calcium carbonate from the previous test before making a determination.
I still find the Abbey Pen a useful rough-and-ready tool for testing older enclosures and paper and for finding the occasional contemporary paper that is not alkaline. So do keep testing!
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Shannon Zachary
Head, Preservation and Conservation
University of Michigan Library
Ann Arbor MI
(734) 358-1367
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Original Message:
Sent: 01-26-2023 13:10
From: Chelsea Sigourney
Subject: Abbey pH Pen
Hello all,
I noticed that the Abbey pH pen we've been using at my institution is marking everything except cardboard as neutral or alkaline. Printer paper, post-it notes, and note cards all appear purple. The pen predates me, so I'm guessing it's at least 7 years old. I assume it has expired, but I had no idea that could happen. Has anyone else come across this?
cheers,
Chelsea
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Chelsea Sigourney
Curator of Exhibits & Collections
Columbia SC
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