Here is still another reason for making digital copies or photocopies of old documents: iron gall ink was the standard writing and drawing ink in Europe, from about the 5th century to the 19th century, and remained in use well into the 20th century. Many of our most valuable documents were written with iron gall ink. However, the ink slowly destroys itself and the paper on which it sits. Words are literally eating themselves into oblivion.
Iron gall ink worked well on parchment, the most common writing material for centuries. However, when the world started moving to paper, problems arose. According to Wikipedia:
“Paper has its own special problems with iron gall ink. The iron-tannic pigment does not make chemical bonds with the cellulose fibers. The ink sticks firmly to the paper, but largely by mechanical bonding; namely, the dried ink penetrates the spaces between the fibers and, after drying, becomes entangled in them. The process of decaying the writing surface is accelerated on paper when compared to parchment, doing the damage in decades or years that could take more than a millennium on parchment.”
The Untold Lives Blog of the British Library describes the damage inflicted by iron gall ink and the describes the (unsuccessful) efforts of the Library’s Conservation Team to stabilize, treat and better understand iron gall ink.
You can read the article at http://blogs.bl.uk/untoldlives/2016/07/words-will-eat-themselves.html.
My thanks to newsletter reader Robin Gruner for telling me about this article.