natural versus synthetic indigo

[Geowu]

maybe this effect - the color variation in the Edo Ai - could be achieved by mixing various batches after they are each dyed separately? (because each must have a slightly different hue) ?

Personally I prefer the darker black-blue which I believe is due to some kind of sulphur dye wash in addition to the indigo -- Pure indigo can be as dark as black (e.g. Studio D'artisan).

Edited by Geowu on May 16, 2006 at 10:54 AM

[ringring]

I've never taken the trouble to count the colours in the Edo's & Hawaii's. There's at least 3 different shades of blue. Then there's the variation of thickness of the warp yarns.

[giantreptile]

i wonder if whatever chemicals used to solubilize the indigo determines the final color, since the color we see depends on indigo's final redox state. just a thought.

[ringring]

Sure does.

Everything has an effect on indigo. That's also the beauty of it. Even just hanging your jeans up for a few months will effect the colour as the indigo oxidises more.

Consider this, modern denim mills will experience colour variation from lot to lot - and this is with using modern technology to regulate the dyes, temperature, PH balance, oxidation times, dip times, yarn circulation, number of dips and the pre-treatment of the cotton and the regulation of the spinning process.

[ringring]

Quote:

maybe this effect - the color variation in the Edo Ai - could be achieved by mixing various batches after they are each dyed separately? (because each must have a slightly different hue) ?

Personally I prefer the darker black-blue which I believe is due to some kind of sulphur dye wash in addition to the indigo -- Pure indigo can be as dark as black (e.g. Studio D'artisan).

Edited by Geowu on May 16, 2006 at 10:54 AM

--- Original message by Geowu on May 16, 2006 10:52 AM

True. You can achieve very dark colours without the use of sulphur.

eg. "Crows Wing" is a description of a colour achieved by French indigo dyers in the 18th century.

[spiveyt2]

There have been a number of remarks as to indigo oxidizing but what exactly happens to it when it does oxidize? I am not speaking chemically, I just want to know what the difference is to the eye. Does it turn a lighter blue, some other color, or what?

[ringring]

what exactly happens to it when it does oxidize?

It goes blue (from yellow straight from the dye vat). A pair of new jeans, even after having a strong industrial wash, will also darken through oxidation if exposed to air, but kept out of direct sunlight. (and, of course, away from any abrasion & washing)

[wild_whiskey]

To add, the oxidization is something any one can see. Put a white cloth in an indigo vat, pull it out, hang it in the air for a moment and watch it turn from a light yellow to an ochre to green to blue. I'm not sure of the chemical properties, but that's what oxidizing does.

[spiveyt2]

Thank you both for answering that question. I had no idea that indigo was yellow in a reductive state. Now, back to wild_whiskey's thoughts earlier on dipping times with jeans, since oxidation is merely a process that turns indigo into the desired color, the time taken in between dip times is more of an evaporative process than an oxidative one? What I mean by that is, according to w_w's experience with a lack of color deepening after 6 dips, it is more a matter of water/other elements evaporating from the denim after a certain time that allows for more indigo to be absorbed into the fabric to increase depth of color after 6 dips? I guess what I am trying to get at is a question I tried to ask in another thread was that at what point does more dipping cease to make a difference. I am sure that this differs based on weight of fabric and other absorbtion properties. I am just skeptical with the marketing of jeans as having "x" amount of dips necessarily being better based on a higher number.

[ringring]

Adding dips is just increasing the concentration of indigo on the yarn, so you're completely correct that it gets to a point of diminishing returns. I think the general concensus is that 6 dips gets a a pretty good quality denim and 16 dips gets you to a point whereby the indigo is actually around 30% of the yarn weight - ie very dark indeed.

As you have surmised, there will be many variables involved, so not every dye vat will ever achieve the same performance. So perhaps what can be achieved in 16 dips by some, is achieved in 20+ dips by others. For instance, the differences between a modern slasher dye set up and an artisan rope dyeing are so great that it would be perfectly reasonable to expect there to be significant variation.

If some marketing claims have been exaggerated then I guess it wouldn't be the first or last time in the world of fashion. After all, aren't all the shuttle looms in Japan supposed to have been bought off Levi's in the 80s?

Ultimately, most people don't get hung up on the dip count & just judge the denim on it's appearance, performance and if they represent value for money for their spending power.

Edited by ringring on May 17, 2006 at 02:50 AM

[Paul T]

Hi ringring,

There's a distinct difference between the looks of ealry 1900s denim, natural indigo, made by Amoskeag and others, and the late 20s denim, synthetic, made by Cone and others. Cone were certainly more mechanised (they were also more efficient, and they were closer to where the cotton was produced).

We're speculating here, but I wonder if

a) the Cone denim was darker because they'd started using sulphur in the process, or..

the Cone denim had more dips, simply because it was cheaper to do so, thanks to the lower cost of synthetic denim, plus other production efficiences.

What do you think?

Incidentally, do you have the Jenny Balfour-Paul book on Indigo? I've attempted ordering it and had problems, now it's pricey, is it worth the price of admission?

[ringring]

That's a very interesting question! I'd never given it much thought before. I wonder what the real answer is?

Yes, I have the JBP book and consider it absolutely brilliant. Just the bibliography in the back is a frightening resource. It's out of print now, so not that easy to get hold of, but I think the British Museum might have a few (literally) copies left.

[trinket]

Thanks ringring.

So the indigo doesn't bond well to the cotton because it's a big molecule and instead it forms a layer/coating over the thread? And multiple dips creates conccentric coatings.

Some manufacturers put the yarn through different dye variations to achieve a depth of color? Is this how sugarcane create the natural indigo/synthetic indigo mix? eg. 8 dips in natural indigo followed by 8 dips in synthetic.

This is all before weaving, so is there a lot of indigo loss during the weaving process?

Is there much indigo loss during sanforization?

(I'm full of questions)

_trinket

[Paul T]

I don't have time to check some of my documentation, and ringring will correct me, but I vaguely recall that an initial sulphur washdown makes the yarn less porous - and saves costs because less indigo soaks in.

Logically, this might be the cause of a lower-contrast fade. Without a sulphur washdown, the indigo adheres more and is harder to chip off.

[trinket]

Perhaps!

It's also possible that the indigo clings better to a porous surface, and flakes off the smoother surface more easily.

We need an electron microscope.

_trinket

Edited by trinket on May 17, 2006 at 04:16 AM

[Paul T]

?

"Without a sulphur washdown, the indigo adheres more and is harder to chip off" and

"the indigo clings better to a porous surface, and flakes off the smoother surface more easily"

mean the same thing...

[trinket]

Sorry for the confusion

Depending on the scale of the porosity (size of the pores) versus the behaviour of the indigo.

"high porosity" could result in less surface area for a molecule to adhere to (if the indigo cannot get into the pores).

_trinket

Edited by trinket on May 17, 2006 at 04:30 AM

[Paul T]

The theory (and it's only a theory, and there are a lot more variables in the process)...

No sulphur washdown = more porous, MORE surface area, more indigo soaks in, and better adhesion. So the indigo chips off less readily, and therefore we see a lower-contrast fade.

Sulphur washdown = less porous finish, the indigo, however dense, sits on the surface and chips off more easily, giving a higher-contrast fade.

trinket, sorry if I expressed this in a confusing way...

ringring, I found a new copy of JPB, thanks for the recommendation, and it's making its way to me from the Lebanon...

Edited by Paul T on May 17, 2006 at 05:13 AM

[ringring]

"So the indigo doesn't bond well to the cotton because it's a big molecule and instead it forms a layer/coating over the thread? And multiple dips creates conccentric coatings.

Some manufacturers put the yarn through different dye variations to achieve a depth of color? Is this how sugarcane create the natural indigo/synthetic indigo mix? eg. 8 dips in natural indigo followed by 8 dips in synthetic."

Hey Trinket. (I like your site BTW).

I'm not going to attempt to talk about molecules But yes, indigo sits on the surface of the yarn. You can easily verify this yourself by taking some indigo yarn from a sample of denim and seeing that the core of the yarn remains uncoloured.

That's not to say that it doesn't bond well with cotton. Is does, and as natural dyes goes, it is exceptional, as it dyes both animal fibre (eg wool) and vegetable fibre (eg cotton, flax etc) very well. In fact, on the subject of sulphur being used to 'bottom' out indigo dyeing - indigo was traditionally used to 'bottom' other natural dyes, to increase their colourfastness.

Indigo's characteristic, for better or worse, is that it rubs off.

"Some manufacturers put the yarn through different dye variations to achieve a depth of color? Is this how sugarcane create the natural indigo/synthetic indigo mix? eg. 8 dips in natural indigo followed by 8 dips in synthetic."

I have no idea how Sugarcane would do it, but there's a history of natural & synthetic dyes being mixed in the same vat - adding the synthetic stuff to give the natural dyestuff a boost (also economically). There's also prior to that, a history of mixing of woad and indigofera.

"This is all before weaving, so is there a lot of indigo loss during the weaving process?

Is there much indigo loss during sanforization?"

Some loss. As basically everything that touches the indigo yarn will cause some rub off. But nothing too serious.

""Without a sulphur washdown, the indigo adheres more and is harder to chip off" and

"the indigo clings better to a porous surface, and flakes off the smoother surface more easily"

mean the same thing..."

I'm not sure of the chemical details, but pre-dyeing with sulphur will indeed make the loss of indigo easier. Hence it's considered by denim purists undesirable. It will also effect colour.

Sulphur can also be added after the indigo dips (sulphur top) to darken the yarn at a lower cost.

Interesting discussion.

[john11f]

Interesting discussion indeed. Again, in lay man's terms is there any premium natural indigo dyed jeans deserve over synthetic indigo dyed? I was under the impression that this is what's supposed to separate japanese premium denim over other else. They just up the ante a step further that it even surpass Levi's' quality. (Not that there aren't any natural indigo dyed non-Japanese brand)

[Paul T]

Although Levi's and Nudie have both produced natural indigo jeans, I believe that the denim for both is produced in Japan. I know Kurabo specialise in it - I'd love to know who produces Sugarcane's Edo Ai and other specialist denim...

[ringring]

" in lay man's terms is there any premium natural indigo dyed jeans deserve over synthetic indigo dyed?"

Where natural indigo has it's value is it's historical heritage. You're directly connected with probably the most important dye ever discovered, with a deep and widespread history from ancient Egypt to the present day. Natural indigo will have graced Viking raiders to Napoleon's armies, Persian rugs to Medievel tapestries, the Emperors' of China to the blue collar (term derived from indigo) workers that made Levi Strauss his fortune. So if you have an historical and/or botanical interest in plant derived indigo, then the premium may be worth it.

That's not to say that synthetic indigo doesn't have a fascinating history of it's own - albeit much, much shorter. And of course there are plenty of jeans that use fantastic quality, synthetic dyed denim.

Again, many brands may use their natural indigo jeans as their flagship styles - so they make take extra care over them - again adding perceived value.

But if you're not interested in indigo's provenance, then I'm not convinced that natural indigo will have necessarily a better colour or fade better than synthetic indigo. (the extra care taken to produce some natural indigo denim notwithstanding).

Edited by ringring on May 17, 2006 at 07:50 AM

[derdankhund]

well damn...score another point for Ring Ring...

You have managed to disabuse me of two apparent myths I had long held dear; natural indigo produces a better fade and that selvage denim, with its cherished inconsistencies, was somehow better...

what i have gathered is that neither of these elements necessarily makes a jean better than its synthetic/non-selvage counterpart; it is the level of craftmanship that will make a jean come out superior in the end. If the oft-lauded japanese repro companies of this board were using non-selvage or synthetic dyes, I have a feelings their products would still be the ones I gravitate to, because they put the most time and quality control into the construction (obviously since most if not all steps are manual...at least for sugar cane and 45rpm).

to give a concrete example, i'll cite a detail that sugar canes possess that was already mentioned in the sugar cane post:

"If you look at those 'Canes - you will see only one stitch on the underside of the felled denim. This indicates that the fell seams have been single stitched then folded together by hand and then edged stitched. A much, much longer process.

On the yoke and crotch, you'll still see a double row of stitching on the outside - and another giveaway is that the stitches on the double row don't run identically parallel stitch for stitch.

It's a detail that you won't find even in the most expensive jeans. It's a 'homemade' way of doing fell seams, that's totally not viable for large production. It's amazing that Sugarcane went to the trouble"

Now hopefully Ring Ring you won't talk me out of the belief that craftmanship is what matters...I think that might be a little more difficult

[sneakeraddict]

presumably Levis no longer make any models with natural??

[Paul T]

not at the moment. THe early 501 reissues, with lighter denim, use Japanese-sourced fabric, but it's synthetic indigo to my knoewledge. AFAIK, only the Nevada Jeans and the so-called 1880 reissues used natural indigo.

[minya]

ringring, what's your background? I've always been curious, since you display an extremely large knowledge of denim that goes beyond what a "consumer" would know. Do you own a denim mill?

[tweeds]

on that note, it would be fantastic if a 45rpm or sugarcane employee turned up on the boards.

believe me guys i'm keeping this particular thread bookmarked.

[minya]

Well, we do have a denim engineer from Levis on the board... I certainly wouldn't be surprised if there were representatives from other companies lurking and reading.

[cheapmuthafukr]

minya, you should sticky this thread. invaluable knowladge here.

If you've lost your faith in superfuture, Oh the end won't be long

Because if it's gone for you then I too may lose it, And that would be wrong

I've tried so hard to keep myself from falling

Back into my bad old ways

And it chars my heart to always hear you calling

Calling for the good old days

Because there were no good old days

These are the good old days

[minya]

Quote:

minya, you should sticky this thread. invaluable knowladge here.

--- Original message by cheapmuthafukr on May 17, 2006 09:09 AM

I'll definitely add it to the list of "denim bible" threads featured in the stickied topic we have above.