Difference between revisions of "Indigo"

Revision as of 11:39, 27 April 2013

Pieced quilt American United States, New York, late 18th century Printed cotton plain weave; pieced and quilted 238 x 183.5 cm (93 11/16 x 72 1/4 in.) Museum of Fine Arts, Boston: Gift of Mrs. Edward E. Harkavy 49.414 for more information see: MFA Online Collections Database

Description

Synonyms and Related Terms

2,2'-biindolinyliden-3,3'-dion; Indigofera tinctoria; Natural Blue 1; CI 75780 (natural); Vat Blue 1; CI 73000 (synthetic); Pigment Blue 66; indigotin; indicum (Pliny); indigo (Esp. Fr., Dan., Ned., Port., Sven.); Indigo (Deut.); anil (Esp.); Indiko (Gr.); indaco (It.); aneel; anile; ai (Jap.); rams (Tibetan); blue ynde; blue inde; anneil; India blue; intense blue; rock indigo; stone blue; indigo carmine; intense blue; indico; indicoe; indego; nil

Photomacrograph of a piece of indigo. Photo credit: Keith Lawrence, Museum of Fine Arts, Boston

Other Properties

Soluble in nitrobenzene, phenol, chloroform, glacial acetic acid. Insoluble in water, ethanol, acetone, ethyl acetate, pinene. Absorption max = 599 (in xylene). ISO R105 Lightfastness Classification = 3-4 Microscopically, indigo has fine, translucent dark blue, rounded particles that are weakly birefringent and appear red under Chelsea filter.

Photomacrograph of indigo powder from the Botanical Museum, Harvard University. Photo credit: Keith Lawrence, Museum of Fine Arts, Boston

Composition	C16H10N2O2
CAS	482-89-3
Melting Point	390-392
Molecular Weight	mol. wt. = 262.26
Refractive Index	>1.662

Brightfield transmitted light photomicrograph of paper dyed with indigo at 50X. Sample provided by the Asian Conservation Laboratory, MFA. Photo credit: Keith Lawrence, Museum of Fine Arts, Boston

Hazards and Safety

Discolored by reducing agents and bleaches. Fisher Scientific: MSDS

Photomacrograph showing paper dyed with indigo. Sample provided by the Asian Conservation Laboratory, MFA. Photo credit: Keith Lawrence, Museum of Fine Arts, Boston

Additional Information

H.Schweppe, "Indigo and Woad", Artists Pigments, Volume 3, E. West FitzHugh (ed.), Oxford University Press: Oxford, 1997. Pigments Through the Ages: Indigo

Normal (left) and UV (right) reflected light images at 100x of pigment/collodion mixture on glass slide to illustrate pigment color along with presence or absence of autofluorescence. Normal light = Halogen lamp (100 W, no filter); UV light=Mercury gas discharge lamp (100W, excitation filter=340-380nm, suppression filter=425 nm). Image credit=Scientific Research lab, Museum of Fine Arts, Boston.

Comparisons

Characteristics of Common Blue Pigments

@@ Line 10: / Line 10: @@
 == Description ==
-A natural dark blue dye obtained from ''Indigofera tinctoria'' plants native to India, Java, Peru, and other tropical areas. The use of indigo was first mentioned in Indian manuscripts in the 4th century BCE. It was exported to Europe in Roman times but did not become plentiful until sea routes opened up in the 17th century. The natural material is collected as a precipitate from a fermented solution of the plant. The coloring component, indigotin, is extracted as a colorless glycoside, but turns blue with oxidation. Synthetic indigo was first produced in 1880 by Adolf von Baeyer. Made from anthranilic acid, the synthetic colorant is chemically identical to natural indigo and has almost entirely replaced the natural dyestuff. Indigo is a fine, intense powder which may be used directly as a pigment in oil, tempera, or watercolor media. The exposed pigment can fade rapidly in strong sunlight. Indigo is still used to dye jeans, where its fading and uneven coloring have become favorable characteristics.
 [[File:indigo tinctoria t.jpg|thumb|]]
@@ Line 20: / Line 20: @@
 == Other Properties ==
-Soluble in nitrobenzene, phenol, chloroform, glacial acetic acid. Insoluble in water, ethanol, acetone, ethyl acetate, pinene.   Absorption max = 599 (in xylene).  ISO R105 Lightfastness Classification = 3-4  Microscopically, indigo has fine, translucent dark blue, rounded particles that are weakly birefringent and appear red under Chelsea filter.
+Soluble in nitrobenzene, phenol, chloroform, glacial acetic acid. Insoluble in water, ethanol, acetone, ethyl acetate, pinene.
+Absorption max = 599 (in xylene).
+ISO R105 Lightfastness Classification = 3-4
+Microscopically, indigo has fine, translucent dark blue, rounded particles that are weakly birefringent and appear red under Chelsea filter.
 [[File:indigo_powder.jpg|thumb|Photomacrograph of indigo powder from the Botanical Museum, Harvard University.
@@ Line 46: / Line 49: @@
 == Hazards and Safety ==
-Discolored by reducing agents and bleaches.  Fisher Scientific: [https://fscimage.fishersci.com/msds/62055.htm MSDS]
+Discolored by reducing agents and bleaches.
+Fisher Scientific: [https://fscimage.fishersci.com/msds/62055.htm MSDS]
 [[File:dyed indigo.jpg|thumb|Photomacrograph showing paper dyed with indigo. Sample provided by the Asian Conservation Laboratory, MFA.