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Tannic acid (Acidum tannicum), a commercial form of tannin
Tannin

Tannins are astringent, bitter plant polyphenols that either bind and Precipitation or shrink proteins. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of red wine or an unripened fruit....
, is a polyphenol
Polyphenol

Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol unit or building block per molecule....
. Its weak acidity (pKa
Acid dissociation constant

An acid dissociation constant, Ka, is a quantitative measure of the strong acid in solution. It is the equilibrium constant for a chemical reaction known as Dissociation in the context of acid-base reactions....
 around 10) is due to these phenol
Phenol

Phenol, also known as carbolic acid, is a toxic, white crystalline solid with a sweet tarry odor, commonly referred to as a "hospital smell"....
 groups in the structure. Tannic acid is a basic ingredient in the chemical staining of wood
Wood

Wood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of woody plants, notably trees but also shrubs, etc....
. The tannic acid or tannin is already present in woods like oak
Oak

The term oak can be used as part of the common name of any of about 400 species of trees and shrubs in the genus Quercus , which are listed in the List of Quercus species, and some related genera, notably Lithocarpus....
, walnut
Walnut

Walnuts are plants in the family Juglandaceae. They are deciduous trees, 10–40 meter s tall , with pinnate leaves 200?900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnut but not the hickory in the same family....
, and mahogany
Mahogany

The name mahogany is used when referring to numerous varieties of dark-colored wood, originally the wood of the species Swietenia mahagoni, known as West Indian or Cuban mahogany....
.






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Bottle of Tannic Acid
Tannic acid (Acidum tannicum), a commercial form of tannin
Tannin

Tannins are astringent, bitter plant polyphenols that either bind and Precipitation or shrink proteins. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of red wine or an unripened fruit....
, is a polyphenol
Polyphenol

Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol unit or building block per molecule....
. Its weak acidity (pKa
Acid dissociation constant

An acid dissociation constant, Ka, is a quantitative measure of the strong acid in solution. It is the equilibrium constant for a chemical reaction known as Dissociation in the context of acid-base reactions....
 around 10) is due to these phenol
Phenol

Phenol, also known as carbolic acid, is a toxic, white crystalline solid with a sweet tarry odor, commonly referred to as a "hospital smell"....
 groups in the structure. Tannic acid is a basic ingredient in the chemical staining of wood
Wood

Wood is an organic material; in the strict sense wood is produced as secondary xylem in the stems of woody plants, notably trees but also shrubs, etc....
. The tannic acid or tannin is already present in woods like oak
Oak

The term oak can be used as part of the common name of any of about 400 species of trees and shrubs in the genus Quercus , which are listed in the List of Quercus species, and some related genera, notably Lithocarpus....
, walnut
Walnut

Walnuts are plants in the family Juglandaceae. They are deciduous trees, 10–40 meter s tall , with pinnate leaves 200?900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnut but not the hickory in the same family....
, and mahogany
Mahogany

The name mahogany is used when referring to numerous varieties of dark-colored wood, originally the wood of the species Swietenia mahagoni, known as West Indian or Cuban mahogany....
. Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react.

Tannic acid is the most common mordant
Mordant

A mordant is a substance used to set dyes on fabrics by forming an insoluble compound with the dye. It may be used for dyeing fabrics, or for intensifying stains in cell or tissue preparations....
 for cellulose
Cellulose

File:Cellulose Sessel.svgCellulose is an organic compound with the chemical formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand ? linked D-glucose units....
 fibers such as cotton
Cotton

Cotton is a soft, staple fiber that grows in a form known as a boll around the seeds of the cotton plant a shrub native to tropical and subtropical regions around the world, including the Americas, India and Africa....
. Tannin is often combined with alum
Alum

Alum, refers to a specific chemical compound and a class of chemical compounds. The specific compound is the hydrated aluminum potassium sulfate with the chemical formula KAl2.12H2O....
 and/or iron
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
. The tannin mordant should be done first as metal mordants combine well with the fiber-tannin complex.

The presence of tannic acid in the bark of redwood (Sequoia)
Sequoia

Sequoia sempervirens is the sole living species of the genus Sequoia in the cypress family Cupressaceae . Common names include Coast Redwood and California Redwood ....
 is a strong natural defense against wildfire
Wildfire

A wildfire is any uncontrolled, non-structure fire that occurs in the wilderness, wildland, or The Bush. Synonyms such as wildland fire, forest fire, brush fire, vegetation fire, grass fire, Peat#Fires, bushfire , and hill fire are commonly used....
, decomposition
Decomposition

Decomposition refers to the process by which tissues of dead organisms break down into simpler forms of matter. Such a breakdown of dead organisms is essential for new growth and development of living organisms because it recycles the finite chemical constituents and frees up the limited physical space in the biome....
 and infestation. It is found in the seeds
SEEDS

SEEDS is a voluntary organisation registered under the Societies Act of India.SEEDS was formed in 1994 as an informal group of students and pedagogues of the School of Planning and Architecture, New Delhi, whose common interests brought them together and made them carry human habitat environment related exercises beyond set academic target...
, bark
BARK

BARK was an early Electromechanics. BARK was built using standard phone relays, implementing a 32-bit binary machine and could perform addition in 150 ms and multiplication in 250 ms....
, cones
Conifer cone

A cone is an organ on plants in the division Pinophyta that contains the plant sexuality structures. The familiar woody cone is the female cone, which produces seeds....
, and heartwood.

The chemical formula for commercial tannic acid is often given as C76H52O46, but in fact it contains a mixture of related compounds. Its structure is based mainly on glucose
Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
 ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
s of gallic acid
Gallic acid

Gallic acid is an organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants....
. It is a yellow to light brown amorphous powder which is highly soluble in water; one gram
Gram

The gram , ; symbol g, is a Physical unit of mass.Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre, and at the temperature of melting ice" , a gram is now defined as one one-thousandth of the SI base unit, the kilogram, or Scientific notation kg, which itself is...
 dissolves in 0.35 mL of water.

A popular home remedy to stop the bleeding after wisdom tooth extraction is applying tea bags (Lipton's or green tea) in the back of the jaws and biting down, given that the tannic acid in tea helps to clot blood.

It is said that soaking feet in tannic acid (or strong tea) can help prevent blisters.

But the use of tea for toughening skin appears to be apocryphal, in as much as tea is said to be incapable of tanning leather.

Tannic acid was once used as a treatment for strychnine
Strychnine

Strychnine is a very toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents....
 poisoning in the late 19th and early 20th centuries.

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