Pierre Galafassi

Hi all,

Mike’s post and his remark «The Mordant is the key. Aluminum for crimson, Tin for bright scarlet, iron for violet, grey, and black» is a welcome pretext for me to mention another, very rare, Turkmen (Salor?) shade: grey.

But first please allow me a short general remark about pre-industrial black and grey shades on rugs and textiles.
It is highly unlikely indeed that black and grey shades were ever made with a recipe using cochineal, for two main reasons:
It would be very wasteful indeed to use expensive cochineal and iron mordant to make a black or a grey.
Besides, it would not even be easy to achieve these shades with this recipe (1). Cochineal/iron is only a sensible choice to make subdued purple and violet shades.

Pre-industrial dyers achieved black and grey with one of the following recipes, mostly using natural grey of brownish wool as a base:

- Un-dyed natural grey wool, shaded if necessary. (But, apparently, not natural black wool (5))
- Tannin and iron salts. (The cheapest way for a black shade but potentially leading to wool degradation. The range of black shades achievable is a bit limited).
- Tannin and iron salts on wool previously dyed with indigo in a deep blue (More expensive, but giving a large range of black shades. Due to the more limited usage of iron salts the risk of wool degradation was much lower too. This was the recipe agreed by King Louis XIV’s nosy bureaucrats for «Grand Teint» black shades (High fastness quality). Similar regulations applied in other countries as well.
- Wool dyed with indigo in a very deep blue (surmey), then «shaded» in a second dyeing operation with madder and / or a natural yellow. The most expensive recipe.

However, a few modern Afghan Turkmen dyers still know that a natural dyestuff which they call "ela-rang" , Alkanna tinctoria in Europe (2), yields beautiful grey shades with bluish or violet cast (3). FIG A shows two examples of shades dyed with alkanna root-chips on alum-mordanted wool.
FIG A.


I would not be surprised if the analysis of the Salor rug below (published in Opie’s «Tribal Rugs») and of some of his extant friends would reveal that the dye used for the pile of the gul was alkanna. IMHO this particular shade of grey would be difficult to obtain with any other natural dye recipe. Proof of the contrary is much welcome.



Neither would I be much surprised if the main users of Alkanna would have been central Asian Jews: The dye is poorly soluble in water (thus difficult to use from an aqueous dye-bath) but very soluble in alcohol / water mixtures. Jews were often the only central Asian ethnic group allowed to make alcoholic beverages. For their own consumption only (at least officially ). This was the case in nineteenth century Bokhara for example. And of course they also were often mentioned as competent dyers, especially involved in the indigo business.

(1) The Turkmen weaver who complained to Madame Moshkova that he would only obtain grey shades with cochineal was probably merely «dyeing» his wool with a dirty component extracted from the insect shell, while all the red carminic acid was precipitated and made unusable by the calcium present in his hard water.
Many users of cochineal dried insects know that during the initial minutes of the dyeing operation this impurity comes out, quickly goes on wool and soils it. Therefore, pre-industrial dyers often sacrificed a few skeins of low-quality wool in the dye-bath to get this dirty «dye» out of it. When this purification was completed they introduced the wool they wanted to dye bright red.
(2) Source: Marc Roy. Private communication.
(3) The roots of Alkanna tinctoria (Anchusa tinctoria, Dyer’s bugloss) and a number of other Boraginaceaes (4), contain a high concentration of a strong dye («alkannin», a naphtoquinon) which on alum-mordanted fibres yields a variety of grey shades on wool and subdued violet shades on cotton. I have seen «bishop violet» shades achieved on wool too (but I haven’t yet found the trick). The light fastness is not good while probably still sufficient for rugs.
(4) D. Cardon . Natural Dyes. Pages 60-66.
(5) Natural black wool is said to have poor light fastness. I have not yet verified this information.

Best regards
Pierre

Steve Price

Hi Pierre

The gray/purple color of two large medallions in the Salor trapping aren't piled in wool, they're silk that's either corroded or abraded down to the knot heads. Does that make any difference in your thinking about the nature of the dye? I was going to ask whether it colors your thinking, but you know how much I dislike word play.

Regards

Steve Price

Pierre Galafassi

Hi Steve,

Whether the pile is wool or silk makes little difference on the shade in this case. The light fastness which is a bit weak on wool could be either worse or better on silk, this can't be predicted and must be tested.
If what we see on the picture is mainly (grey) warp and weft structure with little silk pile left or even the grey wall of the museum behind the rug, yes, that would change the "color of my thoughts".
Could anybody post a closer view of that gul?

Best regards
Pierre

Dinie Gootjes

Hi Pierre,

Dyer's burgloss, typo for bugloss?

I don't know much about dyeing, but I love to read about it. Fascinating what those dyers knew. Thanks for sharing your specialized knowledge again.

Dinie

Joel Greifinger

Hi Pierre,

As per your request



Joel Greifinger

Pierre Galafassi

Yes Dinie it is "Bugloss".
Indeed, the knowledge of the old dyers is fascinating. In many cases one wonders how they could discover a particular process. For exemple several civilizations discovered, independently, that a local plant contains aluminum salts and could be used for mordanting the fibre. A particular anatolian process for making a saturated and wash-fast red on cotton is incredibly complex and the recipe uses a high number of weird components which "raison d'être" is never obvious.

Thanks Joel. Steve was right (a rather frequent occurrence) , the pile is totally corroded and its original shade is now very difficult to tell. Dull bluish red or aubergine perhaps? Such a strong corrosion suggests a dyeing recipe using iron salts as mordant. The ela-rang hypothesis seems quite unlikely in this case.

Best regards
Pierre

Marvin Amstey

A more accurate picture of the corroded silk color should be available by looking at the back. Has anyone seen the backside?

Pierre Galafassi

Steve,

Thanks for having reminded me that parts of the gul were knotted with silk in many Salor rugs. I tend to forget too many things lately (Age-related synapse decay).
I never realized though that so many of them were showing such strong "corrosion" or abrasion of the silk pile.

It would be interesting to find out whether the pile abrasion is "normal" (silk pile has less resilience and resistance to abrasion than wool pile and every genuine Salor rug has been around for at least 150 years) or due to the fibre degradation caused by the mordanting/dyeing recipe (high iron salt content for example).
In the examples below it is sometimes difficult to tell the original shade of the silk, in one or two cases (upper right and left) we can guess a pinkish (cochineal) shade which surely did not use any iron mordant.
As Marvin suggests it could be very interesting to see pictures of the back of some of these rugs.

Steve Price

Hi Pierre

The word "pink" is never used in Rugdom except in a derogatory sense. Every auction catalog and publication I can recall refers to the most common color of silk in Turkmen pile woven stuff as "magenta."

It always looks pretty pink to me, but I'd never admit to that.

Regards

Steve Price

James Blanchard

Hi all,

I have no problem calling this colour "pink". It's better than "fuchsia", which my daughters like to use.

However, I am intrigued that it shows very little sign of corrosion. Was this corrosion strictly a matter of the silk material, or the dying process?

James

Filiberto Boncompagni

One of the things I do remember from my studies on conservation and restoration is that silk is damaged by light. I think the fibre is mostly vulnerable to the UV component.
Regards,

Filiberto

Lloyd Kannenberg

Hello Pierre, Filiberto and all,

The Smithsonian Institution has a site about conservation of silk textiles - concentrating on "crazy quilts", but relevant to all silk textiles. Here's the link:

http://www.si.edu/Encyclopedia_SI/nmah/vicquilt.htm

I think that some Central Asian silk textiles (ikats, for example) are sturdier than American silks of the Victorian Age because they are not so impregnated with mineral salts.

Cheers to everyone!

Lloyd Kannenberg

Steve Price

Hi

Does anyone here know that it's corrosion? I see the same loss thing with silk pile of every other colors, too, and not only in Turkmen textiles. Doesn't matter whether it's magenta, blue, yellow, green - the silk pile has always lost more height than the surrounding wool. My thinking is that it probably reflects the fact that silk has poor abrasion resistance.

Regards

Steve Price

Marvin Amstey

Interesting that you should pose such a question, Steve. I hadn't noticed if all silk pile was lower than wool in the same piece, but it seems to be true in my stuff also. I have a Turkmen (probably Tekke) band that was probably used as a horse necklace for decoration. It is about 6 ft long and 8 in. wide. There are five colors of silk in this piece: yellow, blue, green, light rose (pink?) and magenta. The band was never walked on or physically abraded. The kilim ends and edge finishes are untouched. Everywhere there is silk, the pile is 1-2 mm. lower. Either the dyeing process or perhaps sunlight corroded the silk IMHO, and it must have taken some time. There are a number of new pieces in a shop here in town with varying amounts of silk in the pile from at least three different countries, with 5-10 different colors of silk and this phenomenon is not evident. The silk pile is the same height as the rest of the rug.

Pierre Galafassi

Hi all,
Interestingly your observations point the finger rather to a weakness of the silk fiber (compared to wool).
Light-induced degradation, as suggested by Filiberto is a serious possibility. Another one could perhaps be the fiber pre-treatment: I do not know whether Turkmen (1), Persan or Bokharan weavers used to treat silk in a hot alkaline bath to eliminate non fibrous material and enhance fiber brightness (it is likely though), but 20th century textile plants surely did a preliminary hot soaping (alkaline) which must have impaired somewhat the long term resistance of the polymer.
There is no reason to think that normal alum mordanting and madder- or cochineal dyeing would cause any significant silk degradation. The other mordants (probably) known in 19th century Central Asia (iron, tin and copper) could all be suspected of wreaking havoc in the silk polymer in some cases.
Regards
Pierre

1) Whether Turkmen were active silk dyers is highly debatable, but some Amu-darya Ersari certainly were involved in silk skein production as several 19th century visitors noted.

Steve Price

Hi Pierre

I'd give fiber pre-treatment first place on my list of probable reasons for silk pile wearing or corroding more rapidly than wool.
1. Marvin's piece showing that it happens independently of abrasion reduces silk's poor abrasion resistance to a low probability of being the explanation.
2. The fact that it seems to be independent of the color of the dye reduces the likelihood that it's a result of the dyeing process. It also reduces the likelihood that it's a result of silk's photolability - the dyes would reduce the amount of light reaching the silk itself, and not all to the same extent.

Of course, it could be the result of more than one factor.

Regards

Steve Price

Pierre Galafassi

Hi Steve,

You could be right. I would not exclude photo degradation though:
a) There is a fair probability that relatively high energy UV radiations, if adsorbed by the fibre) would cause more damage than (lower energy-) visible light and
b) The adsorbtion spectrum of visible light by the dye (responsible for the fiber coloration) does not allow to predict in any way the adsorbtion spectrum of UV radiation by the same dye (1), thus the potential damage by UV light.

As mentioned by Lloyd and Filiberto the conservation people seem to think that UV light is their main enemy. I would put my 50 cents on degradation being the result of more than one factor, including poor resistance of silk to UV light.

Best
Pierre

(1) the un-dyed silk polymer itself has a limited adsorbtion of light, be it UV or (obviously) visible light.

Steve Price

Hi Pierre

I understand, although if the dyes are aromatic compounds they probably absorb much more in the UV than they do in the visible range.

I am confused by the footnote on your last message: the un-dyed silk polymer itself has a limited adsorbtion of light, be it UV or (obviously) visible light. I'm assuming that you meant absorption, not adsorption, so that's not an issue. But if undyed silk doesn't absorb UV very strongly, it isn't possible for UV light to do much to silk, not so? My simpleminded understanding of photochemistry includes
1. the notion that photodegradation is a chemical reaction initiated by the action of light on a molecule, and
2. light can only initiate a reaction in a molecule that absorbs it and, therefore, absorbs the energy of the photons. What am I missing?

Regards

Steve Price

Pierre Galafassi

Yes Steve "ab", not "ad", sorry

If silk is victim of light-induced degradation, the odds are for a reaction initiated in the dye since the colorless fibre does not absorb visible light and only little UV, while the dye always absorbs both.
There are several possibilities for such a reaction to "jump" from the dye molecule to the fibre.
The key is how the energy (light) absorbed by the dye is dissipated:
The energy of light can for example be dissipated by inducing a chemical reaction in the dye molecule itself (poor light-fastness), by phosphorescence (delayed re-emission of light), by fluorescence (simultaneous re-emission of light), under the form of heat etc... In some photo-reactions "free radicals" are generated in the dye. These can move from the dye molecule to the fibre and initiate in it a further chemical reaction.
Many cases of "photo-tendering" of fibers in which dyes or other chemicals are the indirect culprits for a fiber degradation are documented.
Best regards
Pierre
P.S. Are we not trying the patience of the many Turkotekers allergic to chemistry?

Steve Price

Hi Pierre

Are we not trying the patience of the many Turkotekers allergic to chemistry?

No pain, no gain.



Regards

Steve Price

Rich Larkin

Hi Pierre,

Don't stop. This is marvelous stuff.

Rich Larkin

Steve Price

Hi Pierre

The free radical route makes sense to me. In phosphorescence and fluorescence, the emitted light is always longer wavelength than the absorbed light. Thus, it's never (almost never?) in the UV range and can't cause any mischief in a colorless molecule like silk.

Regards

Steve Price

Yohann Gissinger

Hello to all,

One of my sciences professor was used to tell us short stories to introduce the lessons and to familiarize us with the subject.
Pierre's lesson could have begun like this:

"Genghis Khan was once said to have issued all his horsemen with silk vests, as an arrow hitting silk does not break it but ends up embedded in the flesh wrapped in silk, allowing the arrow to be removed by gently teasing the silk open, as opposed to the usual method of removing barbed arrows, cutting them out or pushing them right through an injured limb and out of the other side.
These silk vests functioned much like the padded armour used by European and Byzantine soldiers of the era, such as the gambeson (1)"

...then disgressing about the silk degradation under the "attack" of light.

Thank you Pierre,
Y
(1) picked from:http://en.wikipedia.org/wiki/Mongolian_armour

Pierre Galafassi

[quote=Steve Price]

The free radical route makes sense to me. In phosphorescence and fluorescence, the emitted light is always longer wavelength than the absorbed light. Thus, it's never (almost never?) in the UV range and can't cause any mischief in a colorless molecule like silk.

Hi Steve,
You are absolutely right.
I was not suggesting that phosphorescence, fluorescence (or heat) are causing any harm to the fiber or the dye. I was merely listing some of the main possibilities for the dye to dissipate the photo-energy absorbed. Unlike these three rather harmless ways, the formation of free radicals or singulet oxygen (and a few more) dissipate this energy in a potentially destructive way (for the dye or for the fiber).

Hi Rich,
Should I conclude that you enjoy suffering very much?

Hi Yohann,
This is a wonderful story. I suppose that Mr G. Khan had easy access to freshly spun/woven, un-degraded silk. He was said to be very persuasive.

Best regards
Pierre

Steve Price

Hi Pierre

My favorite photochemistry historical tidbit: Alexander the Great knew about photochromic dyes (dyes that change color on exposure to light). He would have his soldiers impregnate strips of cloth with a photochromic dye, wrap it around one wrist, then take their positions the night before a raid. The rising sun changed the colors simultaneously on all the strips, and the color change was the trigger for the perfectly coordinated attack.

This invention has been celebrated in song ever since: Alexander's Rag Timeband.


Regards

Steve Price

Alex Wolfson

Hi Pierre,

A fascinating salon - bravo!

I had a slightly different question about silk pile. On many pieces I have observed a pronounced tip-fading, as well as abrasion.

The received wisdom about woollen pile is that heavy tip fading likely indicates the use of certain synthetics.

I am not so sure about silk though. The silk highlights often appear suspiciously bright on the reverse of the pile (predominantly bright shades were preferred), but we also find very bright shades of silk on textiles such as suzanis, which are commonly held to have been made before the advent of synthetic dyes.

My question is: Does photo-sensitivity make silk more prone than wool to tip-fading, even when organic dyes are employed?

Pierre Galafassi

Hi Alex,

Assuming that we both define tip fading as the loss of color strength (and often of brightness) of the upper part of the pile, its most frequent cause is light-induced fading. Heavy tip fading is mostly a sign of very poor light-fastness (or sometimes of chemical treatment).
Some of the earliest synthetic dyes, the wrongly called "anilin dyes" , (chemically speaking triphenyl-methan cationic dyes) like Victoria Blue, Malachit Green, etc.. had extremely poor lightfastness on wool and silk. Much worse than any other type of dye, natural or synthetic, normally used for rugs. Their bright violet, green or magenta shade typically turned to beige or grey. Significant changes of shade could be seen (comparing tip and roots or pile and back) after a very short time. A few days of exposure outside on a sunny day was all it took.
If we except this specific group of very early synthetic dyes, the light fading of the other nineteenth century synthetic wool- and silk dyes was not, on average, any worse than the average of the few natural dyes selected for wool- or silk rug pile.
Some old synthetic "acid" dyes had a barely acceptable light fastness, (especially some orange and red dyes) but no worse than some natural rug dyes, especially than many yellow and golden-yellow dyes.
A natural red dye quite frequently found on Safavid rugs, for example on so-called "Polonaise rugs", (Safflower red, Carthamus tinctorius) was just as bad (1).

Then we must remember that the lightfastness of a given dye depends also on the fiber on which it is applied: Some early synthetic triphenyl-methan magenta dyes have a reasonable light fastness on cotton but a truly lousy one on wool or silk.

IMHO the fact that madder is relatively less frequent than insect dyes (like cochineal or lac) on silk is not only due to the brighter shades of the latter but, at least in part, also to the fact that madder has a poorer light fastness on silk than on wool.

I am not sure to be able to answer well your last question. I can only say that light-induced fading, in general, impacts both the strength (saturation) and the brightness of a coloration, but I have no clear explanation of any difference of behavior of old silk suzani and silk pile.

(1) The red component extracted from Carthamus tinctoria is another amazing proof of our ancestor's ingenuity mentioned by Dinie in another thread. The plant (flowers) contains mainly a yellow dye of extremely poor lightfastness and only traces (nearly 100 times less) of a beautiful bright red dye. One can wonder how the old dyers discovered the existence of this red dye and found a way to separate it from the useless yellow!

Marvin Amstey

Pierre,
Thanks for your helpful and useful explanations, particularly the points about tip fading from natural dyes. Too often collectors and some arrogant dealers accuse a rug of poor dyes and late age when, in fact, they are uneducated about dyes and their effects on materials. Your 101 and 201 classes here on Turkotek may help improve their knowledge.