Pre-reduced indigo: natural versus synthetic

Name: Jen

Country or region: US

Message: I’m doing research on pre-reduced indigo crystals. I’m finding that they’re being called everything from freeze-dried to instant and claims of them being ‘natural’, extract, etc. This flies in the face of what I’ve also been told directly by an importer- if it comes from India it’s all synthetic. Even the stuff one seller is claiming produced in Japan has an import label from India! So you can see confusion.
Any information or insight you’d be nice enough to share is most appreciated.

Hi Jen,

I believe that I’ve NEVER encountered pre-reduced indigo that was not synthetic. Those who wish to use only plant-derived indigo must do more work to reduce their indigo themselves.

I suspect that there is no difference at all between pre-reduced indigos that are listed as being freeze-dried, dried, or instant, merely different ways of describing the same product. Indigo “extracts” appear always to be the normal oxidized form which must be reduced by the dyer before use. Note that pre-reduced indigo is not 100% reduced; the various retailers all specify that their pre-reduced indigo is 60% reduced. The remaining 40%, which is in the oxidized form, is unusable unless the dyer chemically reduces it in the indigo dyeing vat. (Both synthetic indigo vats and natural fermentation indigo vats produce chemical reduction.)

Often a retailer’s advertising copy reads as though their pre-reduced indigo is natural, but if they are both reputable and careful you can see that it is not. For example, Dharma Trading Company, which is good about what claims they make, says:

As an alternative, try this Pre-reduced Indigo. Synthetic Indigo (chemically identical to natural Indigo) has been pre-reduced chemically, then dried, so it dissolves in water right off the bat….This all makes it have a lower environmental impact for the dyer than taking the original natural or synthetic Indigo from start to finish with all the chemicals involved.

Jacquard Products starts off saying “This natural vat dye exists in plants all over the world”, but concludes clearly with “Jacquard’s indigo is a synthetic organic and comes pre-reduced 60% for unprecedented ease of use.” (source)

“Organic” is a difficult word for the dyer, because an organic chemical is any chemical that contains carbon; it has nothing to do with organic farming. All dyes, whether natural or synthetic, are organic chemicals, aside from a few mineral colors that are not really of interest. However, many dyers mistake claims that a dye is organic, thinking it means it is a plant-derived dye when in fact it is not. Dye sellers sometimes purposefully exploit this confusion.

Jacquard pre-reduced indigo is available through Amazon, as well as other sources; a supplier on Amazon currently selling Jacquard pre-reduced indigo, “The BT Group”, provides misleading information claiming that what they are selling is naturally occurring. There’s an issue with resellers on Amazon, which can post wrong information about their products; it’s likely that The BT Group doesn’t know anything about what they are selling, and merely selected several phrases from the Jacquard copy without paying attention to how they have changed the meaning by omitting a key word. Similarly, Etsy sellers give blatantly false information about whether the pre-reduced indigo dye they sell is from natural sources, when what they are selling is obviously synthetic, given their suppliers.

Earth Guild makes an error, showing instructions for using natural indigo on a page whose title is “PRE-REDUCED INDIGO INSTRUCTIONS”, but I don’t think that the title of a web page amounts to a claim, given that many people who edit web pages don’t even know how to alter the titles of their pages. (source) In corroboration of this interpretation, they have a page on Lanaset dyes with this same webpage title, so it’s just a mistake.

George Weil helpfully says that pre-reduced indigo is used as “an alternative to Natural Indigo”. (source)

There are blogs that have instructions for using pre-reduced indigo which assert that the dye is natural, but in every case it seems that the blogger was insufficiently knowledgeable. Since they’re not selling the dye, they’re not legally liable for their claims in the same way that someone who is selling a pre-reduced indigo is.

If you find any additional information, I will be interested in learning about it!

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Are “Greener Shades” dyes really safer than other acid dyes?

Name: Kathe

Country or region: Denmark

Message: Hi Paula, I would like to read your article on Greener shades dyes vs acid dyes, but it not available on your site, can your help, please? I have been looking for MSDS on these dyes online, with no luck. The dyes are not available in Denmark, but I would like to find out if they really are safer than other acid dyes.

Hi Kathe, I was able to find the article you were looking for. Unfortunately I have never been able to resurrect the Dye Forum, but the Internet Archive has, wonderfully, made a record of its old postings. Here is the original query, followed by my lengthy response, and another dyer’s followup message….

Greener Shades vs Acid dyes

Hey all, I am a professional dyer who has been dyeing with Acid dyes for years with wonderful results. All my colorways are based on these Acid dyes. Recently, I have begun to wonder about the impact of what I do on the environment and so have looked at Greener Shades dyes. After reading the instructions, I see they are actually very similar to the Acid dyes (in processing the color). That makes me wonder if they are really substantially better for the environment or if they are just saying that to sell the product. The label says they do not release heavy metals but I was wondering which class of dye does? Do Acid dyes release these heavy metals or are they referring to vat dyes or Lanaset dyes or what? I want to be sure, before I go to all the time and expense of completely changing my line, that I am in fact doing something to help the world and not just falling for an advertising gimmick. Could anyone one who has looked into the facts please tell me what they have discovered? I would greatly appreciate it. Gale

By gale evans at 2011-08-09 06:24

Greener Shades not so impressive

The Greener Shades dyes are chrome-free acid dyes, but, 1, that’s true of many dyes already on the market, and 2, chrome-containing premetalized dyes are not all that bad, at least when used in the small quantities needed for hand dyeing. The fact that the Greener Shades company does not give any Colour Index names or any other generic names for their dyes makes it impossible to know whether to trust their MSDS forms (which incidentally, are very confusing, apparently ranking midnight black as both severely hazardous and perhaps not hazardous at all – very bad MSDS writing!).

Apparently the Greener Shades do not have Colour Index names at all, which makes me suspect that they might be too new to have had thorough safety testing. They list their Organic Processing Compliance Testing Results, but apparently these refer only to heavy metal content, and say nothing else about the safety of these dyes for the environment! There are plenty of dyes which are free of significant metal content but which will kill fish if they get into streams. If a dye persists in the environment and is toxic to animals, plants, or microbes living in it, it would be no better than a dye that contains a little heavy metal.

What bothers me the most about their claims is that, while their MSDS pages give too little information to reassure me, they have no safety testing certification at all. I need to know what the generic names for dyes are, so that I can look them up elsewhere to find out whether they pose any particular hazard. Since Greener Shades does not give this information at all, we can have no idea how safe these dyes really are to use.

Chrome dyes, by the way, are a class of synthetic dyes that are mordanted, as natural dyes can be, with dangerous carcinogenic hexavalent chromium (sold as potassium dichromate). They have both better leveling AND better washfastness than other classes of wool dyes, where normally a wool dye’s leveling is inversely proportionate to its washfastness, and vice versa. However, I do not recommend the use of chrome dyes by artists (not that any of us have a good source for buying them), just as I do not recommend the use of natural dyes that are mordanted with chrome. There’s too much risk of exposure to the hexavalent chromium, and such a large amount of the hexavalent chromium in the mordanting process is used that it’s bad for the environment, as well. Metal complex dyes, or premetalized dyes, which includes many of the Lanaset dyes, are NOT dangerous like the chrome dyes and the natural dyes that are mordanted with chromium. Metal complex dyes have a smaller number of chromium atoms included in their molecular structure, and they are in the vastly safer trivalent form. Only the hexavalent form of chromium is a known human carcinogen. Incidentally, most exposure to hexavalent chrome occurs in applying industrial processes that do not include textile dyeing.

My conclusions for now:

1. Go ahead and use those of the Lanaset dyes or other premetalized dyes that contain chromium, in small quantitities, mixing up no more dye than you are likely to use, and disposing of them as per EPA regulations, which require that the dyes be diluted if they are put down the sewer (household waste water being suitable for this purpose). (As I explained in my All About Hand Dyeing Blog here, “a dye painting solution of 1 teaspoon of Jet Black Lanaset dye that contains 2.5 grams of dye, dissolved in one cup (250 ml), contains 0.08 grams (which is equal to 80 milligrams or 80,000 micrograms) of chromium. After being diluted with 50 gallons of uncontaminated water, this dye concentration would meet the US EPA standard for chromium content of drinking water in the US, which is 100 micrograms per liter.”)

2. If you want to avoid heavy metals, use only those Lanaset dyes which are metal free (see my page, Which Lanaset dye colors are pure, rather than mixtures?), or use other classes of acid dyes which do not contain heavy metals, such as most of the WashFast Acid Dyes (with the exception of the Jet Black, which is a premetalized dye).

3. If you order from Greener Shades, insist that they give you certification of environmental safety testing, not only for lack of heavy metals, as provided by a named third party company, but also for the potential environmental dangers of the specific dye molecules used. Do not ever accept vague claims of safety that are not backed up by a certification and the contact information for the company that did the testing, because it’s so easy for a company to make claims that are not backed up by any proof.

To find out whether the acid dyes you use contain heavy metals, check the MSDS information for them. Your dye supplier should give you this information; both ProChem and Dharma make things easy by supplying them on their website, but others will send you the MSDS with an order, or following an order, for whatever you have purchased from them. You could also post about your favorite dyes here, so we can discuss their safety.

If a dye contains a heavy metal in its chromophore, it’s probably only a problem when it is used in large industrial quantities. There is absolutely no reason, for example, for a hand dyer to worry about the 2% of the weight of turquoise dyes that is present as copper; almost all good bright turquoise dyes contain a copper atom in their chromophore. (This is true of the Greener Shades aqua color, as well!) The copper ion remains bound in the dye molecule until it is broken down, and it is not present in harmful quantities unless you are running a large dyeing factory. The salt used with the dye is probably of larger concern, environmentally.

You mention vat dyes. The environmental and safety aspect of using vat dyes, such as natural indigo, is that you must use significant quantities of lye and other chemicals, unless you are using one of the very slow and less predictable fermentation baths; however, these chemicals are not bad once their pH has been neutralized. Vat dyes do not require mordants.

In most lines of dye, a few colors contain small amounts of heavy metals such as copper. Other colors often do not.


By pburch at Tue, 2011-08-09 07:11

Greener Shades Coral Reef Agua

This color does contain copper and does not meet organic specs. This info is buried on the Greener Shades FAQ page, But this info is hard to find and not front and center on the main page. Further if their non-toxic quality is the reason for selling them as “Greener shades” why is it being sold at all? Many dyers are shocked to get this info after using them.

“Why do you carry a dye, Coral Reef Aqua, that does have a heavy metal in it?”

“To get a really true and bright aqua or turquoise color, it is extremely difficult to do so without the introduction of some sort of metal compound. Our customers demanded a turquoise color, so we had to compromise on this one color. The heavy metal used is copper and the dye analaysis is listed in the “Dye Info” section of our website. This color does not meet the requirements of the Organic Trade Association for organic textile processing, but it is still manufactured with the same high quality performance and sulfonation balance as our other colors.”

By brigidsfarm at Tue, 2011-08-16 09:18

I can’t, as I write this, view the Greener Shades website because for some reason my web browsers are telling me that the site is not safe to connect to, so I can’t see if their current claims have changed at all. However, the Greener Shades Dyes FAQ is printed on the website for the C & M Acres Fiber Mill; it claims that the dyes are safer solely because they do not contain metals, although in fact one of them does, and metals are not always a significant danger for dyers. Furthermore, there are many dyes which are quite dangerous to use, in spite of their being free of heavy metals, such as some of the Naphthol dyes; I’m sure that the Greener Shades dyes are much safer to use than the more dangerous of the Naphthol dyes, but the fact that they are metal-free is irrelevant with respect to the many dangerous organic chemicals that exist. We need Greener Shades to supply more proof of the safety of their dyes, before we can have any reason to believe their claim that their dyes are safer.

There is one group of acid dyes that are probably safer than other acid dyes, which are the food coloring dyes. Unlike (as far as we can tell from the information they supply) the Greener Shades dyes, food coloring dyes have been proven to be quite safe to work with, because they have been tested for being reasonably safe even when eaten (though I confess to feeling that people should not eat them often, and certainly never in the quantities found in a confection called Red Velvet cake). See my page, “Using Food Coloring as a Textile Dye for Protein Fibers“.

You can browse the Internet Archive’s copy of the Dye Forum at their website at

You are also always welcome to ask me to help track down any information I can find.

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Bleaching a black t-shirt is producing orange – How can I get white?

Hi Paula,

I have a project that I am trying to achieve a certain garment treatment. I am attaching an image of the design. I have tried using bleach on a black garment but end up with an orange under-color and my client is looking to get it as close to white as possible – see picture. Do you have any other treatment suggestions on how to achieve this look?

Best regards,


Hi Tim,

t-shirt print with white sections

Your picture of the desired results [shown to the right] appears to show the use of an opaque white screen-printing ink. The white is so bright and so devoid of variation that it doesn’t have the look of bleached-out dye, to me.

Discharging black garments is a perennial problem. Most commercially-available black garments are dyed with unidentified dyes that will discharge unpredictably.

The spider-web pattern on this navy blue shirt discharged with bleach to a pink color.

Unless a shirt is sold with specific claims as to dischargeability, you never know whether it will discharge to white, or to an aged-looking orange or brown, or even refuse to discharge at all, remaining black. Some dyes cannot be discharged at all. Black garments may have been originally intended to be black, or they may have been overdyed with black dye after dyeing with another color produced undesirable results; if the other colors are non-dischargeable, you could get an entirely unpredictable color. A supply of black blanks may discharge well and then suddenly, after many successful uses, be replaced, with absolutely no notice from the manufacturer, by black shirts that do not discharge acceptably!

To complicate matters, while results will be pretty much the same with one reducing-type discharge as another, the results may be very different from those obtained by discharging with an oxidative discharge such as chlorine bleach or dichloroisocyanurate. Bleach may produce an entirely different color than a reductive discharge. For more information on this, see my page, “What chemicals can be used to remove dye?”. If you ever use Procion dyes yourself before discharging, also check out my page “Which Procion MX dyes discharge the best? Which are good at resisting chlorine bleach?”.

I recommend that you search specifically for a dischargeable black blank t-shirt for dyeing. There are some on the market. Ask your current suppliers if they can supply you with some, or do a search including the word “dischargeable” to locate another supplier. Alternatively, consider the use of an opaque white screenprinting ink. For example, Jacquard Professional Screenprinting Ink in the color “Super Opaque White” gets good reviews for being very opaque, though I don’t have personal experience with it.

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