Editing Ink (section)

== Health and environmental aspects ==
{{See also|Environmental issues with paper}}
{{More medical citations needed|section|date=June 2018}}
There is a misconception that ink is non-toxic even if swallowed. Once ingested, ink can be hazardous to one's health. Certain inks, such as those used in digital printers, and even those found in a common pen can be harmful. Though ink does not easily cause death, repeated skin contact or ingestion can cause effects such as severe headaches, skin irritation, or nervous system damage.<ref>{{Cite web|url=https://www.dovemed.com/healthy-living/first-aid/first-aid-ink-poisoning/|title=First Aid for Ink Poisoning|website=www.dovemed.com|year=2018|access-date=2019-01-18}}</ref> These effects can be caused by solvents, or by pigment ingredients such as [[p-Anisidine|''p''-Anisidine]], which helps create some inks' color and shine.

Three main environmental issues with ink are:
* [[Heavy metal (chemistry)|Heavy metals]]
* Non-renewable oils
* [[Volatile organic compound]]s

Some regulatory bodies{{Specify|date=June 2023}} have set standards for the amount of heavy metals in ink.<ref>[https://web.archive.org/web/20070508062911/http://cpima.org/HeavyMetals.pdf Canadian Printing Ink Manufacturers' Association]</ref> There is a trend toward [[vegetable oil]]s rather than [[petroleum oil]]s in recent years in response to a demand for better [[sustainability|environmental sustainability]] performance.

Ink uses up non-renewable oils and metals, which has a negative impact on the environment.<ref>{{Cite news|url=http://tenrandomfacts.com/ink/|title=Ink – Ten Random Facts|date=2013-07-15|newspaper=Ten Random Facts|language=en-US|access-date=2016-11-29}}</ref>

=== Carbon ===
[[File:Inkstick.jpg|right|thumb|Chinese [[inkstick]]; carbon-based and made from [[soot]] and [[animal glue]]]]
Carbon inks were commonly made from lampblack or soot and a binding agent such as [[gum arabic]] or [[animal glue]]. The binding agent keeps carbon particles in suspension and adhered to paper. Carbon particles do not fade over time even when bleached or when in sunlight. One benefit is that carbon ink does not harm paper. Over time, the ink is chemically stable and therefore does not threaten the paper's strength. Despite these benefits, carbon ink is not ideal for permanence and ease of preservation. Carbon ink tends to smudge in humid environments and can be washed off surfaces. The best method of preserving a document written in carbon ink is to store it in a dry environment (Barrow 1972).

Recently, carbon inks made from carbon nanotubes have been successfully created. They are similar in composition to traditional inks in that they use a polymer to suspend the carbon nanotubes. These inks can be used in inkjet printers and produce electrically conductive patterns.<ref>{{Citation|last1=Simmons|first1=Trevor|year=2007|title=Large Area-Aligned Arrays from Direct Deposition of Single-Wall Carbon Nanotubes|journal=J. Am. Chem. Soc.|volume=129|issue=33|pages=10088–10089|url = http://pubs.acs.org/cgi-bin/article.cgi/jacsat/2007/129/i33/html/ja073745e.html|doi=10.1021/ja073745e|pmid=17663555|last2=Hashim |first2=D |last3=Vajtai |first3=R |last4=Ajayan |first4=PM |bibcode=2007JAChS.12910088S |postscript=.|url-access=subscription}}</ref>

=== 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>