Talk:Indigo dye

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Dying Process[edit]

  • Should something be mentioned about how fabric is dyed? Indigo is insoluble in water...I believe it is reduced into something water soluble (it's yellow in color at that point), applied to fabric, then oxidized back to indigo. Just a thought :-) 71.242.135.83 05:20, 29 June 2006 (UTC)
  • Indigo is slightly soluble in hot water. To dye with indigo place the indigo powder in the bottom of a large pot of water. Add the item to be dyed and barely simmer until the desired shade is produced. Stirring the item helps keep the dying even. Please note that, in use on fabric, indigo wicks moisture. It helps make cloth cooler. It works well on white cotton to speed the cotton drying in the sun without lowering the cooling properties of cotton fabric. However, it does make white cotton warmer in the sun. On wool, it makes the wool more cotton-like in properties. The indigo covers the surface of the wool fibers and destroys the natural qualities for which wool is praised. If you want your wool to be warm and at the same time not white, use natural colored wool from dark colored sheep. Dying wool with indigo will make the wool a bit cooler to wear. When indigo dyed wool is wet, it holds the moisture and is cold. My Flatley (talk) 23:39, 29 November 2010 (UTC)

Page move[edit]

  • I suggest moving Indigo dye to Indigo and the color article from Indigo to Indigo (color). Whether this is done or not, the dis-ambiguation page will remain at Indigo (disambiguation). At this moment, take, for example, Gold, which isn't titled "Gold (element)" despite the color, Gold (color), that was named after it. 66.245.1.229 20:02, 6 Nov 2004 (UTC)
    • Good as it is, IMO; colors and underlying substances are too much of a mixed bag for a consistent naming formula; in this case the color is what most people think of first, if only because of Mood Indigo. --Jerzy(t) 05:00, 2005 Feb 9 (UTC)

Chemistry[edit]

Why just an empirical formula, which is of little interest? I don't know that we need a structure diagram (tho i dare say we could get one drawn for the article), but even if it's one of those multi-ring structures where an "edge" is shared between two ring polygons (something that i'm not sure i could grasp in a structural formula) it shouldn't be that cryptic to count the rings and specify their individual structures. --Jerzy(t) 05:00, 2005 Feb 9 (UTC)

FD&C Blue 2[edit]

The FD&C regulation lists CAS numbers for the different forms of indigotine that are allowed in food, but when I tried to find them, all except for 860-22-0 drew a blank. What is going on here? Did the FDA screw up here, have the numbers changed, or does PubChem just not have the others? Here is the quotation from the page:

(a) Identity. (1) The color additive FD&C Blue No. 2 is principally the disodium salt of 2-(1,3-dihydro-3-oxo-5-sulfo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid (CAS Reg. No. 860-22-0) with smaller amounts of the disodium salt of 2-(1,3-dihydro-3-oxo-7-sulfo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid (CAS Reg. No. 54947-75-0) and the sodium salt of 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indole-5-sulfonic acid (CAS Reg. No. 605-18-5). Additionally, FD&C Blue No. 2 is obtained by heating indigo (or indigo paste) in the presence of sulfuric acid.

Also, I will be adding a section on the food use of the dye here. --Slashme 07:36, 23 December 2005 (UTC)


That same link from the FDA says specifically that FD&C Blue No. 2 (the above mixture) is obtained by sulfonation of indigo dye - i.e. indigo carmine. these are distinct compounds; this should be corrected. looks like there are a few different compounds and mixtures we should distinguish here; the plant extract, the synthetic mixture, and the sulfonated versions thereof. 66.253.2.98 (talk) 21:24, 13 May 2009 (UTC)

History[edit]

Can someone tell me why my edit in this section was removed which was "In literature, the drama NIldarpan (the blue mirror ) by Dinabandhu Mitra is based on the indigo slavery and forceful cultivation of indigo (nil ) in India. It played an essential part in so called indigo revolt (nil bidraha ).Often this work is compared to Uncle toms cabin." ? Dinabandhu Mitra's drama nildarpan was very essential in what is called the indigo revolution in Bengal. Calling it substandard or unknown only shows the closedness of mind.Jeroje 03:29, 19 July 2007 (UTC)jeroje

I am not the one who removed it originally, but it is unlikely that the book should only be mentioned here on the indigo article and no where else. I am making no claim as to the merit of the book, but if it is as notable as you say it should have its own article, which could them link to this article. If the book was instrumental in a revolt regarding indigo trade that could be explained in the article on the book, and maybe we could have a section in this article about the revolt (depending on its importance to the global history of indigo). - cohesion 00:30, 21 July 2007 (UTC)
As you know that wikipedia India and in particular wiki Bengal is still a long way behind. There are plenty of issues to be documented. Probably an article for Dinabandhu Mitra should be requested but ignoring this important bit of history is regretable. Its very funny that there is no mention of the region which produced the most amount of indigo in india and hence world (refer to the article ) and no comment on the indigo production process before the laboratory process was invented. Jeroje 10:53, 22 July 2007 (UTC)jeroje
Now the article is linked with Dinabandhu Mitra, if you have any comments about the article please write to me, thanks Jeroje 12:26, 22 July 2007 (UTC)jeroje
I didn't mean no article in the Indian or Bengali wikipedia, I meant in english. I see you have created a nice article at Dinabandhu Mitra! Thanks!. I went ahead and cleaned up that section in this article a little. You are right the history section could definately be improved, probably we should break it up into subsections since a megalith "History" is a little difficult. - cohesion 15:17, 22 July 2007 (UTC)
I was talking about the wiki project India and wiki project Bengal, there are only about 8 members who are listed under wiki project Bengal. Its not atall enough compared to the importance of the region. I was simply refering to this. But thanks for editing the section, Although nilbidraha is about the indigo trade it does not tell the full sotry if we insist on mere trade. it was more political at that time,There was a popular saying in Bengal that traslated into english means "the indigo was more red than blue with the blood of the poor", its surely an important history. I am working on the article I hope to clear this.

Surely the history section can be broken up into subsections, I will be glad to help. Jeroje 04:19, 23 July 2007 (UTC)jeroje

The Blues?[edit]

Perhaps readers could be told of the comment of the Father of American Psychiatry, Benjamin Rush, who, when discussing the effect of odours on mental illness on page 32 of his book, Medical Inquiries and Observations upon the Diseases of the Mind (1812) said: "From among many other facts that might be mentioned, to show the connection of odours with a morbid state of mind, I shall mention one more. An ingeneous dyer, in this city, informed me that he often observed the men who were employed in dying blue of which colour indigo is the basis, to become peevish, and low spirited, and never even to hum a tune, while engaged at their work." -Chris Brown, http://ages.ca

I don't believe an observation like this will stand up to scientific rigours of today. It may warrant a mention as trivia, but not really a subheading under mental effects. --Meekywiki 14:53, 25 August 2007 (UTC)
Thousands of scientific articles would show you are wrong, but I am tired of dealing with Wikipedia bullies. Your removal of this information adds to the argument that a substantial number of ignorant and presumptuous contributors to Wikipedia inviziblize the ongoing injury and killing of persons who are adversely affected by chemicals. - Chris Brown.

—Preceding unsigned comment added by 216.106.110.100 (talk) 16:59, August 25, 2007 (UTC)

Hi Chris, I think your accusation of bullying is unwarranted. If you would kindly provide links to any recent (last 50 or so years?) papers published in reputable sources that show that indigo dye is linked to serious illness or death then we would be happy to include your information in the article. Also, please sign your posts using four tildes(~). Thank you, Capuchin 09:32, 29 August 2007 (UTC)

In music the term “blues” originally derived from the fact that persons turn the color blue when they are poisoned to death with cyanide. The music term “swing” originally derived from lynching. The term “rock and roll” originally referred to hitting someone over the head with a rock and stealing their bankroll. I have no published source for this; take it anyway you like. Joni Mitchell’s song “Blue” makes light reference to the original meaning of “the blues”. This has little to do with dying cloth. But that is how the term originated. My Flatley (talk) 23:59, 29 November 2010 (UTC)

Blue 2 in sweets.[edit]

Does anyone happen to have a list of sweets containing Indigotine? —Preceding unsigned comment added by Leviathan207 (talkcontribs) 21:55, 5 June 2008 (UTC)

Content removed without comment[edit]

In this edit a few paragraphs which seem reasonable at face value were removed without so much as an edit summary. Was it really bad copy? Was it incorrect? Was it POV? --Slashme (talk) 06:42, 12 August 2008 (UTC)

Tyrian purple[edit]

I am going to remove the following sentence in the history (classical antiquity) section:

"The Phoenicians were particularly famous for their mass production of these dyes in classical times, and gigantic mounds of the discarded seashells are still to be found near the ancient cities of Tyre and Sidon They so dominated production of the dye that it was often referred to as "Phoenician (or Tyrian) purple".[2]"

Tyrian purple was not made from the indigo plant, it was made from the murex snail. Even the chemical structure is a bit different. The Phoenicians were certainly famous for dye, just not dye made from indigo the plant.

AllGloryToTheHypnotoad (talk) 22:12, 4 January 2009 (UTC)

That's been a niggle for some time: go on, quick as you like! --Old Moonraker (talk) 22:24, 4 January 2009 (UTC)

Corrections and updating[edit]

This entry on indigo needs correcting, for example, indican is the precursor of indigo found in leaves; and not as stated in the second sentence. The entry also and needs updating - for example we now know how indigo was reduced and thus dissolved in the medieval woad vat, and there are more useful references than some of those provided. I agree with the suggestion that this entry be entitled indigo, and the other be entitled indigo (color). —Preceding unsigned comment added by Ymlaen (talkcontribs) 15:17, 27 May 2009 (UTC)

Well, editing by knowledgeable folks is the way that articles improve. So go for it. If you are a new at editing, then it is usually a good idea to make small edits vs a major rewrite. I think that the second sentence is not meant to be taken literally as becomes clear at one reads the rest of the article. Sometimes, efforts to be highly explicit can detract or distract. But good luck.--Smokefoot (talk) 00:17, 30 November 2010 (UTC)
I agree completely about renaming the articles. - PKM (talk) 03:09, 30 November 2010 (UTC)

Chemical properties[edit]

What is the reference for this section? "The molecule absorbs light in the orange part of the spectrum (λmax = 602 nm)." seems to be incorrect, or at least inexact. The reference I have, J. Wouten and A. Verhecken, JSCD, 107, (1991), p266-269 has λmax = 613 nm, though I suspect it shifts in different solvents, pH etc.Rgbutler (talk) 03:54, 21 April 2011 (UTC)