The condition of ancient manuscripts can become compromised due to a variety of reasons. In this brief article, we want to explain some of the reasons that manuscripts deteriorate. Keep in mind that the Center for the Study of New Testament Manuscripts (CSNTM) strives to use high-resolution digital photography to preserve the exact contents of manuscripts like these before degeneration prevents readability. It’s a reason CSNTM does what it does!
Iron Gall Ink
Iron gall ink deterioration is one of the most troublesome problems in the conservation of ancient manuscripts. Iron gall ink was in wide use between the 9th and 19th centuries. The deterioration is produced by the reaction of tannic acid with an iron salt, such as ferrous sulfate. The solution oxidizes and turns brown when it is applied to manuscripts and exposed to air. Iron gall ink can cause severe degradation in parchment. Almost all ink used on parchment manuscripts was of this variety because the ink adhered to the parchment well. Unfortunately, it also degrades the text and can be difficult to read.
Burnthrough, Haloing, and Lacing
Burnthrough, haloing, and lacing are other kinds of deterioration. “Haloing” is when a light brown halo spreads out from the inked area. “Burnthrough” is when the ink appears to sink through the manuscript and become increasingly visible on the reverse side. Higher-grade parchment, known as vellum, is especially susceptible because such leaves were prepared to be ultra thin. Sometimes burnthrough is so bad that the text actually eats away at the parchment, leaving holes in the manuscript. “Lacing” is when inked areas become so weak and brittle that they crack, crumble, and fall out.
Smoke & Water Damage
Some manuscripts have been damaged by fire and smoke. When they were rescued with water, the leaf itself could be compromised, and water can cause planar distortion in the parchment.
When manuscripts were left in a warm, humid environment for too long, mold can take hold and cause severe damage. Active mold can secrete an enzyme that breaks down the cellulose fibers of paper. The affected areas can be powdered away, becoming thin and particularly weak.
Flaking Ink and Pigment
Compared to paper, parchment is not porous on the surface as it is made of stretched animal skin—such as calf, goat, or sheep—treated with an alkaline solution. Humidity may constantly cause inks and pigments to crack and flake off.
Red Rot Leather
Some manuscripts’ leather covers display damage called “red rot” that produces a powdery red layer of rotted leather.
Some aging leathers may be deteriorated by sprinkled acid that cause the leather to darken in areas exposed to the acid. Others had been torn away or partially missing.
The pigment used in illuminated manuscripts and hand-colored maps is a copper corrosion product treated by copper with vinegar. It becomes dark, turns brown, and shows through to the other side of the page.
Much of this information on manuscript deterioration was taken from the University of Chicago Library’s work: “Under Covers: The Art and Science of Book Conservation.” To listen to a podcast on photographing the “Wee Beastie,” click here.