Iron gall ink (also known as common ink, standard ink, oak gall ink or iron gall nut ink) is a purple-black or brown-black
ink made from
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
salts and
tannic acids from vegetable sources. It was the standard ink formulation used in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
for the 1400-year period between the 5th and 19th centuries, remained in widespread use well into the 20th century, and is still sold today.
Preparation and use
The ink was traditionally prepared by adding some
iron(II) sulfate (
Fe S O4) to a solution of
tannic acid, but any iron ion donor can be used. The
gallotannic acid was usually extracted from
oak galls or
galls of other trees, hence the name.
Fermentation or
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
Biological hydrolysi ...
of the extract releases
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
and
gallic acid
Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants ...
, which yields a darker purple-black ink, due to the formation of iron gallate.
The fermented extract was combined with the iron(II) sulfate. After filtering, the resulting pale-grey solution had a binder added to it (most commonly
gum arabic) and was used to write on
paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distribu ...
or
parchment
Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins ...
. A well-prepared ink would gradually darken to an intense purplish black. The resulting marks would adhere firmly to the parchment or
vellum
Vellum is prepared animal skin or membrane, typically used as writing material. Parchment is another term for this material, from which vellum is sometimes distinguished, when it is made from calfskin, as opposed to that made from other anim ...
, and (unlike
india ink or other formulas) could not be erased by rubbing or washing. The marks could only be erased by scraping a thin layer off the writing surface.
Chemistry
By mixing tannin with iron sulfate, a water-soluble
ferrous tannate complex is formed. Because of its solubility, the ink is able to penetrate the paper surface, making it difficult to erase. When exposed to air, it converts to a
ferric tannate, which is a darker
pigment. This product is not water-soluble, contributing to its permanence as a writing ink.
The darkening process of the ink is due to the
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
of the iron ions from ferrous (Fe
2+) to ferric (Fe
3+) state by atmospheric
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
. For that reason, the liquid ink needs to be stored in a well-stoppered bottle, and often becomes unusable after a time. The ferric ions react with the tannic acid or some derived compound (possibly
gallic acid
Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants ...
or
pyrogallol) to form a
polymer
A polymer (; Greek '' poly-'', "many" + '' -mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
ic
organometallic compound.
While a very effective ink, the formula was less than ideal. Iron gall ink is acidic. Depending on the writing surface being used, iron gall ink can have unsightly "ghost writing" on the obverse face of the writing surface (most commonly parchment or paper). Ultimately it may eat holes through the surface it was on. This is accelerated by high temperature and humidity. However, some manuscripts written with it, such as the ''
Book of Magical Charms'', have survived hundreds of years without it damaging the paper on which it was used.
History
The earliest recipes for oak gall ink come from
Pliny the Elder, and are vague at best. Many famous and important manuscripts have been written using ferrous oak gall ink, including the
Codex Sinaiticus
The Codex Sinaiticus ( Shelfmark: London, British Library, Add MS 43725), designated by siglum [Aleph] or 01 (in the Gregory-Aland numbering of New Testament manuscripts), δ 2 (in the von Soden numbering of New Testament manuscript ...
, the oldest, most complete
Bible
The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity
Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus ...
currently known to exist, thought to be written in the middle of the fourth century. Due to the ease of making iron gall ink and its quality of permanence and water resistance this ink became the favored one for scribes in the European corridor as well as around the Mediterranean Sea. Surviving manuscripts from the
Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
as well as the
Renaissance
The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ide ...
bear this out as the vast majority are written using iron gall ink, the balance being written using lamp black or
carbon black inks. Many drawings by
Leonardo da Vinci
Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested on ...
were made with iron gall ink. Laws were enacted in Great Britain and France specifying the content of iron gall ink for all royal and legal records to ensure permanence in this time period as well.
The popularity of iron gall ink traveled around the world during the colonization period and beyond. The
United States Postal Service
The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or Postal Service, is an independent agency of the executive branch of the United States federal government responsible for providing postal service in the ...
had its own official recipe that was to be used in all post office branches for the use of their customers. It was not until the invention of chemically-produced inks and writing fluids in the latter half of the 20th century that iron gall ink fell from common use.
Waning use
The permanence and water-resistance of the iron and gall-nut formula made it the standard writing ink in Europe for over 1,400 years, and in America after European colonisation. Its use and production started to decline only in the 20th century, when other waterproof formulas (better suited for writing on paper) became available. Today, iron gall ink is manufactured by a small number of companies and used by fountain pen enthusiasts and artists, but has fewer administrative applications.
Fountain pens
Traditional iron gall inks intended for dip pens are not suitable for
fountain pen
A fountain pen is a writing instrument which uses a metal nib (pen), nib to apply a Fountain pen ink, water-based ink to paper. It is distinguished from earlier dip pens by using an internal reservoir to hold ink, eliminating the need to repeat ...
s which operate on the principle of
capillary action. Ferro-gallic deposit accumulation in the feed system can clog the small ink passages in fountain pen feeds. Further, very acidic traditional iron gall inks intended for dip pens can corrode metal pen parts (a phenomenon known as
redox reaction/
flash corrosion). These phenomena can destroy the functionality of fountain pens.
Instead, modern surrogate iron gall formulas are offered for fountain pens, such as blue-black bottled inks by
Lamy (discontinued in 2012),
Montblanc (discontinued in 2012), Chesterfield Archival Vault (discontinued in 2016), Diamine Registrar's Ink, Ecclesiastical Stationery Supplies Registrars Ink, Hero 232, and Organics Studios Aristotle Iron Gall.
Other manufacturers offer besides blue-black other colored iron gall inks such as Gutenberg (certificate ink G10 black), KWZ Iron Gall inks, Platinum Classic inks, Rohrer & Klingner "Salix" and (purplish grey) "Scabiosa" inks, and Stipula Ferrogallico inks for fountain pens.
These modern iron gall inks contain a small amount of ferro-gallic compounds and are also more likely to have a formulation which is
stoichiometrically
Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions.
Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals ...
optimised. Historical inks often contained excess acid which was not consumed in the oxidation of the ferro-gallic compounds. Modern formulations also tend to use
hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dige ...
whereas many historical inks used
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
. Hydrochloric acid is a gas in solution, which will evaporate. As a result, modern fountain pen iron gall inks are less likely to damage paper than historical inks and are gentler for the inside of a fountain pen, but can still cause problems if left in a pen for a long period. Manufacturers or retailers of modern iron gall inks intended for fountain pens sometimes advise a more thorough than usual cleaning regimen – which requires the ink to be flushed out regularly with water – to avoid clogging or corrosion on delicate pen parts. For more thoroughly cleaning iron gall ink out of a fountain pen, sequential flushes of the pen with water, diluted vinegar or citric acid (to flush out residual iron gall compounds), water, diluted ammonia (if needed to flush out residual colour dye stains), then finally water are often recommended.
The colour
dye
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and ...
in these modern iron gall formulas functions as a temporary colourant to make these inks clearly visible whilst writing. The ferro-gallic compounds through a gradual oxidation process cause an observable gradual colour change to grey/black whilst these inks completely dry and makes the writing waterproof. The colour-changing property of the ink also depends on the
properties of the used paper. In general, the darkening process will progress more quickly and visibly on papers containing relatively high
bleaching agent residues.
Though not in mainstream 21st-century use like dye-based
fountain pen inks, modern iron gall inks are still used in fountain pens where permanence is required. In the United Kingdom the use of special blue-black archival quality Registrars' Ink containing ferro-gallic compounds is required in
register office
A register office or The General Register Office, much more commonly but erroneously registry office (except in official use), is a British government office where births, deaths, marriages, civil partnership, stillbirths and adoptions in Eng ...
s for official documents such as
birth certificate
A birth certificate is a vital record that documents the birth of a person. The term "birth certificate" can refer to either the original document certifying the circumstances of the birth or to a certified copy of or representation of the ensui ...
s,
marriage certificates,
death certificates and on clergy rolls and ships'
logbooks. In Germany the use of special blue or black or documentary use permanent inks is required in (
Civil law notary legal instruments).
German regulation for inks (1933)
* In a litre of ink there must be at least 27 g of tannic acid and gallic acid, and at least 4 g of iron content. The maximum iron content is 6 g/L.
* After 14 days' storage in a glass container the ink must not have stained the glass or show sedimentation.
* Eight-day-old writings, after washing with water and alcohol, must remain very dark.
* The ink must flow easily from the pen, and may not be sticky even immediately after drying.
U.S. government "standard ink" formula (1935)
* 11.7 g tannic acid
* 3.8 g
gallic acid
Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants ...
* 15 g
iron(II) sulfate
* 3 cm
3 hydrochloric acid (used to prevent sediment forming)
* 1 g
carbolic acid (phenol, ,
biocide) (preservative)
* 3.5 g
china-blue aniline dye (water-soluble)
* 1000 cm
3 distilled water
The ''
Popular Science'' iron gall writing ink article also mentions
methyl violet
Methyl violet is a family of organic compounds that are mainly used as dyes. Depending on the number of attached methyl groups, the color of the dye can be altered. Its main use is as a purple dye for textiles and to give deep violet colors in pai ...
dye could be used to make a violet iron gall ink without revealing the amount and soluble
nigrosine dye for an immediate black iron gall ink. To avoid the toxic carbolic acid biocide used as a
preservative
A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or b ...
in the U.S. government "standard ink" formula, 2 g
salicylic acid can be used as a safer biocide alternative to prevent
mold in the ink bottle. Both preservatives are enhanced by lowering the pH-value (acidifying the ink by adding hydrochloric acid).
Indian Standard 220 (1988)
In India, the IS 220 (1988): Fountain Pen Ink – Ferro-gallo Tannate (0.1 percent iron content) Third Revision standard, which was reaffirmed in 2010, is in use. This Indian Standard was adopted by the
Bureau of Indian Standards
The Bureau of Indian Standards (BIS) is the National Standards Body of India under Department of Consumer affairs, Ministry of Consumer Affairs, Food & Public Distribution, Government of India. It is established by the Bureau of Indian Standa ...
on 21 November 1988, after the draft finalized by the Inks and Allied Products Sectional Committee had been approved by the Chemical Division Council. IS 220 prescribes the requirements and the methods of sampling and tests for ferrogallo tannate fountain pen inks containing not less than 0.1 percent of iron.
Annex M stipulates that the IS 220 reference ink shall be prepared according to the following formula:
*4.0 g tannic acid
*1.5 g gallic acid
*5.5 g
ferrous sulfate crystals
*5.0 g concentrated hydrochloric acid
*5.0 g dye, ink blue (see IS 8642 : 1977)
*provisional dye (for inks other than blue black) As advised by supplier.
*phenol (see IS 538 : 1968)
*distilled water (to make the total volume one litre).
The IS 220 reference ink shall not be used for more than one month after the date of preparation and shall be stored in amber-coloured reagent bottles (see IS 1388 : 1959).
See also
*
Atramentum
*
Alizarine ink
*
Pen and ink
*
Oak marble gall
*
Ohaguro
*
Stark's ink
Stark's ink is one of a number of types of homemade inks whose recipes were widely available in the 19th century. People often made their own ink before
commercially available ink was inexpensively and easily obtainable.
Dr. James Stark was a che ...
References
External links
Iron Gall Ink – Traveling Scriptorium – A Teaching Kit by the Yale University Library 21 March 2013The Iron Gall Ink WebsiteForty Centuries of Ink by David Carvalho (Project Gutenberg)IRON GALLATE INKS-LIQUID AND POWDER by Elmer W. Zimmerman, U.S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS RESEARCH PAPER RP807 Part of Journal of Research of the National Bureau of Standards, Volume 15, July 1935
{{DEFAULTSORT:Iron Gall Ink
Inks