Editing Ink (section)

=== Iron gall (common ink) ===
{{main article|Iron gall ink}}
Iron gall inks became prominent in the early 12th century; they were used for centuries and were widely thought to be the best type of ink. However, iron gall ink is corrosive and damages paper over time (Waters 1940). Items containing this ink can become brittle and the writing fades to brown. The original scores of [[Johann Sebastian Bach]] are threatened by the destructive properties of iron gall ink. The majority of his works are held by the German State Library, and about 25% of those are in advanced stages of decay (American Libraries 2000). The rate at which the writing fades is based on several factors, such as proportions of ink ingredients, amount deposited on the paper, and paper composition (Barrow 1972:16). Corrosion is caused by acid catalyzed hydrolysis and iron(II)-catalysed oxidation of cellulose (Rouchon-Quillet 2004:389).

Treatment for preservation is a controversial subject. No treatment undoes damage already caused by acidic ink. Deterioration can only be stopped or slowed. Some{{who|date=March 2011}} think it best not to treat the item at all for fear of the consequences. Others believe that non-aqueous procedures are the best solution. Yet others think an aqueous procedure may preserve items written with iron gall ink. Aqueous treatments include distilled water at different temperatures, calcium hydroxide, calcium bicarbonate, magnesium carbonate, magnesium bicarbonate, and calcium hyphenate. There are many possible side effects from these treatments. There can be mechanical damage, which further weakens the paper. Paper color or ink color may change, and ink may bleed. Other consequences of aqueous treatment are a change of ink texture or formation of plaque on the surface of the ink (Reibland & de Groot 1999).

Iron gall inks require storage in a stable environment, because fluctuating [[relative humidity]] increases the rate that formic acid, acetic acid, and furan derivatives form in the material the ink was used on. Sulfuric acid acts as a catalyst to cellulose hydrolysis, and iron (II) sulfate acts as a catalyst to cellulose oxidation. These chemical reactions physically weaken the paper, causing [[Brittle Books Program|brittleness]].<ref>Henk J. Porck and René Teygeler, Preservation Science Survey (Washington, D.C.: Council on Library and Information Resources, 2000).</ref>