Foxing is an age-related process of deterioration that causes spots and browning on

paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, Textile, rags, poaceae, grasses, Feces#Other uses, herbivore dung, or other vegetable sources in water. Once the water is dra ...

document A document is a writing, written, drawing, drawn, presented, or memorialized representation of thought, often the manifestation of nonfiction, non-fictional, as well as fictional, content. The word originates from the Latin ', which denotes ...

s such as

book A book is a structured presentation of recorded information, primarily verbal and graphical, through a medium. Originally physical, electronic books and audiobooks are now existent. Physical books are objects that contain printed material, ...

postage stamp A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail). Then the stamp is affixed to the f ...

s, old

paper money Paper money, often referred to as a note or a bill (North American English), is a type of negotiable promissory note that is payable to the bearer on demand, making it a form of currency. The main types of paper money are government notes, which ...

and certificates, and on textiles such as clothing and artists' canvasses. The name may be a variant form of the English

West country The West Country is a loosely defined area within southwest England, usually taken to include the counties of Cornwall, Devon, Dorset, Somerset and Bristol, with some considering it to extend to all or parts of Wiltshire, Gloucestershire and ...

dialect term ''foust'' and Scots ''foze'', to become moldy. Alternatively, it may derive from the fox-like reddish-brown color of the stains. Paper so affected is said to be "foxed". Foxing is seldom found in

incunabula An incunable or incunabulum (: incunables or incunabula, respectively) is a book, pamphlet, or broadside (printing), broadside that was printed in the earliest stages of printing in Europe, up to the year 1500. The specific date is essentiall ...

, or books printed before 1501. Decrease in rag fibre quality may be a culprit; as demand for paper rose in later centuries,

papermakers Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a special ...

used less water and spent less time cleansing the rag fibres used to make paper. An early work of art to have been affected by foxing is the '' Portrait of a Man in Red Chalk'', a drawing on paper by

Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 1452 - 2 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 o ...

. Foxing also occurs in biological study skins or specimens, as an effect of chemical reactions or

mold A mold () or mould () is one of the structures that certain fungus, fungi can form. The dust-like, colored appearance of molds is due to the formation of Spore#Fungi, spores containing Secondary metabolite#Fungal secondary metabolites, fungal ...

melanin Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes. There are ...

. Textiles, such as articles of clothing, so affected may also be said to be foxed. Aside from foxing, other types of age-related paper deterioration include destruction of the

lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidit ...

sunlight Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...

and absorbed atmospheric pollution, typically causing the paper to become brown and crumble at the edges, and

acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

-related damage to cheap paper such as

newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has ...

, which manufacturers make without neutralizing acidic contaminants.

Causes of foxing

The causes of foxing are not well understood. One conjecture is that foxing is caused by a

fungal A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as one of the tradit ...

growth on the paper. Another is that foxing is caused by the effect on certain

s of the

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

iron Iron is a chemical element; it has symbol Fe () 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, forming much of Earth's o ...

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

, or other substances in the pulp or rag from which the paper was made. It is possible that multiple factors are involved. High

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

may contribute to foxing.

Repairing foxed documents

Foxed documents can be repaired, with greater or lesser success, using

sodium borohydride Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula (sometimes written as ). It is a white crystalline solid, usually encountered as an aqueous basic solution. Sodi ...

, proprietary bleaches, dilute

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

lasers A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

. Each method risks side effects or damage to the paper or ink. Another method is to scan the image and process that image using a high-level

image processing An image or picture is a visual representation. An image can be two-dimensional, such as a drawing, painting, or photograph, or three-dimensional, such as a carving or sculpture. Images may be displayed through other media, including a pr ...

program. This can usually remove the effects of foxing while leaving text and images intact.

In biological specimens

It is generally not advisable to repair study specimens, except perhaps for mechanical damage.

Type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

s should – if at all possible – not be altered in any way. If foxing affects the study value of a specimen (e.g. in

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

or mammal skins or in

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

, where it may affect diagnostic coloration), this might rather be remarked on the specimen label. Color standards can provide a means of documenting coloration before or in the early stages of foxing.

References

Cited Sources

Related Works

* Smithe, Frank B (1974): ''Naturalists' Color Guide Supplement''. American Museum of Natural History, NYC. . * Smithe, Frank B (1975-): ''Naturalist's Color Guide''. American Museum of Natural History, NYC. . * Smithe, Frank B (1981): ''Naturalist's Color Guide Part III''. American Museum of Natural History, NYC. . *

External links

The Library of Congress: 'Preserving Works on Paper'

Foxing
{{Paper Book collecting Materials degradation Papermaking Philatelic terminology