Michael Bischof

First of all I appreciate the subtle politenss of the author:
,,Another well known blogger once claimed that a Persian master-dyer told him that the secret of the bright Salor red was in using madder with a very alkaline desert plant in the dye bath that affected the color and made it bloom (3). Something must have been lost in translation:..."
I would express it stronger. This claim is pure nonsense and the fact that it is apparently impossible to get the name of this ,,Persian master-dyer" makes one suspicious. Yes, one may use some alkali to establish the right pH of a madder dye bath - but together with a surplus of some acid so that the dye bath retains a slightly acidic pH value. Any other thing is just a waste of valuable madder dye stuff.

Second I applaud the empirical approach of Pierre Galafassi. To dye material, publish the essence of what he had done and show the result, instead of decades of meaningless talking and discussions without substance.
Unfortunately he was a bit too careful. With such low amounts of madder he cannot come closer to Salor red.

Third: his essay is, according to my knowledge, the first one which emphazises the importance of ,,minor" mordant auxilliaries like calcium or magnesium (or tin) for the final nuance of the dye lakes. It makes me laugh to see how long it took, as it is so obvious for people who have a practical approach to natural dyes because they make them (as opposite to just talking about them, even if supported by analytical tools).

,,Occam's razor would, therefore, suggest that tin mordanting was the secret of Salor dyers. In order to confirm this theory, an analytic assessment of tin in bright red shades would be necessary. Unless I err, so far only an assessment of the dye was performed in a few cases and madder was found."

So what is the conclusion? If only madder was found in Salor red shades it means that any hypothesis based on insect dyes is wrong within this context.
In the sense of Occam's razor I would state that this bright Salor red is nothing ,,out of this world". It is a very carefully done madder only dye, executed in such a way that one has only alizarine and pseudopurpurine as constituents of the final dye lake (and nothing else from madder!) - and to obtain that I would use 250% of the wools weight of the best available (Anatolian; it is better than Turcomanian) madder.
Not impossible to dye the same quality today; but economically this would make no sense. People like to talk about excellent rugs but when it comes to action they prefer to buy cheap. The claim that the secret of Salor red is lost appears to be a kind of ,,Lebenslüge" of antique dealers, kind of unfounded fairy tales.

Hard or soft water is unimportant. A master dyer knows how to get soft water out of hard water in case he needs that and vice versa.

I would continue to talk about insect dyes as part of the Salor red (on wool!) in the very moment when somebody can show analytical results proving that they had been applied to get that nuance.

The following I would reject as being unsound:
,,(13) Tin salt used as mordant tends to build unevenly on wool and therefore may lead to abrash; it can also make wool brittle. A reasonably low concentration of tin salt in the mordanting bath (2-5% wof of SnCl2) and a very thorough rinsing after dyeing appear to be sufficient cure for the latter inconvenient. (% wof means weight of mordant as a percentage of weight of fiber)."
First of all: SnCl2 cannot be dissolved in water in a proper way. It immediately starts to form a milky sediment. When the wool is immersed one has to rise the temperature over 60°C to get a mentionable mordanting effect. But then, second argument, the wools integrity is destroyed and cannot be recovered by rinsing. If one does not heat, however, there is no mordanting effect. To mordant with SnCl2 in such a way that the wool is not brittle and will corrode is a very, very tricky task. And the dyers responsible for the dyes of Turcoman weaves (do we have real evidence that they were Turcomans?) did not master this process. This is obvious by the fact that all wool or silk in early Turcoman weaves that were dyes using tin mordants are corroded, brittle, feeling like metal wire, not like wool or silk.
Outside of the world of hobby dyers I first heard about the importance of tin as a subtle nuancing help (when mordanting wool with alum in a tin-lined copper pot) in 1982 from Josephine Powell. As she worked together with Harald Böhmer for DOBAG at that time I do not know whether this aspect came from Mr. Böhmer or not.

In the eighties, before we had introduced the use of HPLC with Diode Array UV/Vis detection, I once saw an Anatolian yastik with the most stunning red that until now I ever saw in an oriental weave and at that time I came to the conclusion that in addition to madder they must have had used tin - but in a successful, not corroding way. It was most likely just a kind of happy happening as a twin piece of it, from the same location (both were A-pieces in my terminology) did not show this quality of red, though it was of the same age in any other respect. This yastik ended in the leading yastik collection of Keith Holmes and was exhibited in the frame of ICOC in the USA.
I have to admit that the picture will not display its beauty - for technical reasons.



And, as a proof of concept, another picture of scarlet (Cochineal on a tin mordant) on Mohair: old, not antique, Karapınar ceğiz corap (socks) dyed by Memduh Kürtül in the nineties for a leading German collector of kilims. No corrosion at all, of course.

Pierre Galafassi

Hi Michael,
Thank you for your very interesting comments.

Unless I err, there is only one major point on which we fully disagree: The use of tin (or tin and alum mixes) as being the «little secret» of the bright Salor red.
Your hypothesis is that by increasing the madder concentration of the dye-bath from 100% wof (as in the few examples shown in my essay) to, say, 250% wof, one would obtain a bright Salor red with alum, without the need of any tin mordant. Right?

Let’s first agree about which kind of Salor red we are discussing. My essay targeted specifically those reds featuring a much brighter and saturated red shade than usual for Turkmen and not the various saturated but dull ones which are much more common on Turkmen rugs of all origin, including Salor.

From previous posts of yours, I take it that you have knowledge of dyeing, thus you must know by experience (and from the knowledge of the basics of colorimetry) that increasing the concentration of a rather dull chromophore (or mix thereof) in the dye-bath will of course lead to a more saturated shade (under the same and proper dyeing conditions), [b]but it will also always make the shade duller. The only way to achieve a saturated and bright shade is to use a brighter chromophore to start with.

Every single component of madder on alum-mordanted wool leads to various but invariably relatively dullish shades (from «tomato» to «brick»), and of course, their mixes make the shade, if anything, even duller.
Every single component of madder on tin-mordanded wool are significantly brighter than (the same) alum-mordanted ones.

Although the usual laws of colorimetry apply to all dyes, -natural & synthetic- you will perhaps find solace in the fact that I did not rely only on theory or experience, but did include various dye concentrations (roughly between 10% wof and 200% wof in my little experimental program and that it confirmed the rule mentioned.

It is true (as I mentioned earlier in an answer to Marla) that increasing the dye concentration in the madder dye-bath changes their relative concentration on the fiber, thus influences a little the shade, but it does not help much the brightness and IMHO it cannot be the «little secret» of the Salor. I do of course respect your opinion, but allow me to argue my point a little more.

These changes (as I mentioned in the post to Marla) are due to two main reasons:

a) The various red components of madder do compete with each other for an access to the fiber. Without going into too many boring details of the mechanism of wool-dyeing, each of these red molecules feature somewhat different levels of «hydrophoby», «affinity» and even «molecular size» (dimension), since some are still in glycosidic form (linked to a sugar to make it simple) while others are already aglycones (freed from the «sugar»), some contain a carboxylic acid substituent and some don't. Thus they are not perfectly «compatible» as we say in our obscure dyer’s jargon.

b) Some dye components (most prominently pseudo-purpurine ) are not very stable and can incur in reactions of «decarboxylation», «hydrolysis», etc.. In the case of pseudo-purpurine, (which, together with alizarine, you suppose to be the key for the making of a bright Salor red) it tends to transform itself into purpurine, this chemical change being rather quick in a hot dyeing bath and being influenced as well by the pH.
Focussing on your hypothesis: : «In the sense of Occam's razor I would state that this bright Salor red is nothing, out of this world". It is a very carefully done madder only dye, executed in such a way that one has only alizarine and pseudopurpurine as constituents of the final dye lake (and nothing else from madder!) - and to obtain that I would use 250% of the wool’s weight of the best available (Anatolian; it is better than Turcomanian) madder.», I am sorry to say that I disagree with this statement:
1) A dye-bath with «only alizarine and pseudo-purpurine» implies, in my modest opinion, a cold dyeing operation (I believe that in any «normal», hot-dyeing with madder you would inevitably have a large concentration of purpurine and much less pseudo-purpurine, would you agree?).
2) My own lab trials (still, about a dozen so far) with high concentrations of madder in the bath and various cold dyeing conditions (thus with probably the closest possible composition to the one you expect to be favorable for a Salor bright red, yielded significantly more yellow shades (dullish coral to dullish orange) than the usual turkmen brick to tomato shades obtained with alum mordants in various hot (and therefore poor in pseudo-purpurine) conditions. Thus things aren't quite going the right direction, are they?

Besides, making a very saturated shade in a cold dyeing process is not a piece of cake (very long operation!!).

I happen to have at least one rug in my collection in which the madder dye was applied in what the dyer describes as a «summer fermentation» process, meaning a very long process (several weeks) at an average temperature probably close to 40-50°C. The shade was, I suppose, likely to have been more influenced by pseudo-purpurine than the average hot dyeing process, but the shade, while superbly saturated, is not in any way a bright «Salor red».

Let’s agree to disagree on this will you?: I do believe that madder mordanted with alum has little or no chance to achieve the bright Salor red shades discussed in this thread and that tin is still the more likely «culprit».

Now for a couple of minor details:

1) I haven’t spoken in my thread of cold mordanting with tin, did I? It is true that tin chloride (which, as such, is water soluble, by the way) converts (in a few minutes) in a poorly soluble white hydrate suspension. But, this suspension lends itself quite well to a normal mordanting, under any usual hot conditions (Tests run between 60° and 90°C were all OK, please note also the use of the «cream of tartar» buffer in the mordanting recipe ).

2) Having tested my tin-mordanted, madder-dyed wool samples with various ISO and AATCC -normed fastness tests (competently run by my former company’s lab) and having done a few more tests which were the fruit of my own hardly limited phantasy (like long exposure outside, including months on the roof, rubbing fastness, etc..), I feel confident that the wool was not damaged by the tin mordanting & rinsing treatment. It did not come as a surprise to me though, since contrary to your informations, tin-mordanting on wool is not a process recently introduced by hapless hobby dyers, but was well known and much used by pre-industrial eighteenth century European dyers, was well documented and was «sanctified» as the only accepted method to obtain the «grand teint label» for bright reds. There is no reason to believe that this process could not have been discovered, even earlier perhaps, in other parts of the world.
Anyway my opinion is that tin-mordanting might be, potentially, a threat to the stability of the wool polymer, but avoiding corrosion is not such a « very very tricky task» after all, if only wasting some good fresh water for a very thorough rinsing is sufficient (I swear I did nothing more complicated than that, neither do the eighteenth century recipe books mention any Harry Potter trick). Then, Michael your flashing bright red socks do not feature any suspect hole do they? Unless the dyes were synthetic or Einstein’s cleverer brother was the madder/tin dyer......

3) The fact that tin chloride (probably because of the imperfect solubility of its hydrate) tends to distribute itself more unevenly on wool than alum is very easy to verify. I invite you to try it by yourself. It would never be a problem in any modern industrial dyeing machine of course, but an abrash is more difficult to avoid in my old AHIBA lab dyeing machine. It would be even worse in any pre-industrial or tribal «equipment». But then Salor Turkmen never had the reputation of being incompetent dyers, did they?

4) As you have surely understood while reading my paper, my point was that madder & tin is sufficient to obtain brighter reds, of the Salor type, but would these guys also have mastered the use of cochineal (thus understood the necessity of using soft water for it), they could have done even better (a brighter red still). As I wrote earlier, there is no experimental proof yet that they did so, but, to my very limited knowledge, very few Salor bright reds have been tested sofar. So, IMHO, «it does not prove that any hypothesis based on insect dyes is wrong within this context», it rather means that there is no experimental proof yet to a reasonably credible hypothesis. Do you agree?
Like you , I am also quite content with leaning back in my rocking chair and wait for somebody's hard work to bring any evidence, pro or contra.

5) Thanks for the flowers Michael, but I would never undully claim that I am the first one who «emphasises the importance of minor mordants like calcium, magnesium or tin». In fact I know of a handful of good university papers which explored their influence on cotton- and wool dyeing. Including one from Marmara University, therefore surely well known to Prof. Böhmer too. Although these students were usually virgin of any knowledge of dyeing science (this is no oxymoron!) or of industrial dyeing, some of these papers are very interesting indeed.


I apologize to the other Turkotek readers for being such a monomaniacal serial bore.

Pierre

Michael Bischof

Hi Pierre,

nice to be in a vivid communication.

Yes. To put it strict: ,,...one wone would obtain a bright Salor red with alum, without the need of any tin mordantould obtain a bright Salor red with alum, without the need of any tin mordant." Whether ,,one" would I do not know but I am sure ,,one could", as we have done it often. See below on how our approach was.

Let me try to separate some issues here more clear:
- the use of madder only in combination with a tin mordant (substantial, measurable amount of tin in the dye lake)
- the use of insect dyes to ,,highlight" the vividness of the nuance in addition to madder
- the planned use of tiny amounts of tin only to add a desired ,,fire red nuance" to a madder-only red based only on alum
(The socks are Cochineal only on a kind of tin mordant without any alum, the yastik is in my opinion an alum-based madder red topped by a tin mordant and using Cochineal then: but I could not do any analysis and come to this opinion only by comparison with own practical work!)


Indeed, I meant what the experienced collectors would call ,,early Salor".

This statement I would question. In my experience alizarine and pseudopurpurine are bright enough. The culprits for dullness are other ones. But of course it is true that above a certain concentration any chromophore will give a dull result, even luteoline.

This I do not know as I never tried tin on more or less pure purpurin and the other, less significant minor dye stuffs in madder. Purpurine and a collective that we call ,,dirt" in our practice of dyeing make certain madder lakes dull.


Why cold? You could as well try

* to use a clean madder extract (rich in alizarine, pseudopurpurine, poor in purpurine and ,,dirt"). But then the ,,secret" moves from your dye lab to the lab of the person who makes such an extract...
* establish conditions so that purpurine and ,,dirt" do not much contribute in forming a dye lake

But of course to work cold might be easier.

Indeed, therefore costly.

I know only one person who works like this. But in this case the will be virtually no pseudopurpurine at all, but a lot of purpurine and ,,dirt". No wonder that the result is dullish. Some more words about how you could obtain knowledge of how the dye in your particular rug was done? Nice, but quite unusual, isn't it?

Well, this difference of opinion we will not be solved within this thread as it is not possible to prove results by digital photos. My own way of ,,testing" it was different: take own dye samples or, even better, weaves to opportunities where collectors show and tell their best pieces. Then manage to view their beste ,,Salor reds" in the same illumination together with your sample. I did this many times; the last event that I remember happened at the Hammelessen-event in Graz/Steiermark in Austria, when a collector from Linz showed some striking early Salor cuvals. We compared them with fire red samples done from madder only (without any tin). They were identical, at least for the viewers, the collector and for me.

Well, I saw no mordanting recipe. But a hydrate suspension in a mordanting solution I would call a technical mistake (until it is dissolved again).

Well, I did not state that tin-mordanting of wool is a recently introduced thing. And the many pre-industrial European dye books were well aware that very often the tin mordanting process resulted in corrosion. And, yes, they liked it nevertheless as it was sometimes striking, especially with insect dyes. Madder on tin mordants I rarely found there.

No, Einstein's cleverer brother was Memduh Kürtül who did not do such things a lot, but at least more than about 10x. The corap are without holes from the dyeing process. Happy you: I could not find thorough rinsing to be enough in case the wool was once damaged by wrong tin mordanting.

How do you know who made the dyes? That they appear in Salor weaves must not mean that members of the Salor tribe did the dyeing operations. My own field work in Turkey suggests that all ,,great" dyes have been done by professional dyers in some townships, not by villagers, especially never by nomadic people. ,,Flowers of the yayla" are - flowers.

Michael Bischof

(Sorry, my answer was apparently too long for the system here)

I dislike the rocking chair but I have no access to the necessary apparatus and no funding for doing such research. What should be done is easy, as I guess:

* HPLC with UV/Vis diode array detection of more Salor reds. In this way one can either confirm or discharge the assumption that insect dyes played any role, the tin hypothesis is not affected
* to research, whether one can find enough tin the dye lake of a Salor red to speak of a ,,tin mordant" (alone or in addition to alum)

If these 2 questions are solved one ,,hypothesis" may remain to be an open question: the suggestion of Josephine Powell that the tiny amounts of tin that dissolve when one mordants wool with alum in a tin-layered copper pot are enough to produce a desired fire-red, vivid shade on a madder-only red dye lake on wool. Whether it is analytically possible to witness such tiny amounts of tin against a relatively huge amount of alum you will most likely know better than I do.

Could you be so kind to publish the source of such papers here? I did not hear of such papers, which must not mean much.

Äh, pretending to be modest. Have you often visited Iran? This type of ,,display" I remember from there. As long as you continue to found your theoretical considerations by own practical work that one may visualize you are sufficiently above the level of the crowd.

A Turcomaniac who would not be interested in lifting the secret of Salor reds should change his hobby. Such people would read even longer stuff with ease.

Pierre Galafassi

Hi Michael,

I do not see much fun at further discussing differences of opinion except when new facts are involved. I believe that I did describe my base of information already, as you have yours.
As I said, let’s agree to disagree on the main issue. Nothing wrong with that.

Thus, this post will focus only on answering a couple of open questions of yours:

Tin chloride hydrate: The white dispersion is poorly soluble but not insoluble. Under normal mordanting conditions the solubility is largely good enough for allowing the tin salt to exhaust on wool. The «percentage of exhaustion» is comparable with the one of alum. Nothing strange or exceptional about a dispersion «exhausting» properly on a fiber, believe me Michael. For example the apptly called «disperse dyes» which are the only way to dye polyester, have a very low solubility in water too (a few mg/l at 20°C) but are nevertheless perfectly suitable for dyeing this fiber. Dyeing wool with the so-called «2/1 chrome complexes» (again the most used range for this fibre) is a very similar case.

To call applying tin chloride in its hydrate form a «technical mistake» is your very personal opinion to which you have an imprescriptible right. I do not share
it.

The eighteenth century «grand teint» standard implied sufficient wet-and light-fastness but required also that the dyed textile would not self destroy. A «corroding» process (like tanin/iron for black shades) was not acceptable for the «grand teint label». Tin-based recipes (with both cochineal and madder) were evidently perfectly under control of those dye masters. You may have noticed that a few experiments of mine do confirm the suitability of tin, did you?.

The reason why I know which natural dyes are present in my rugs and some tiny details about the process to boot, is because I work since over 25 years with a friend of mine who operates a rug dyeing- (natural dyes) and weaving operation in central Asia. He is kind enough to create special pieces for me. It’s tremendous fun for both, by the way. This friend has a truly unique practical knowledge of the matter.

Even if you would start with pseudo-purpurine of pharmaceutical purity, any hot dye process would convert it largely to purpurine. (Do you believe that this is not the case?).
This is why, especially for any normal pre-industrial dyer (who was perfectly unable to get pure pseudo-purpurine, or pure alizarine for that matter) a cold dyeing process is the best ( the only?) way to lure at least some pseudo-purpurin on the wool, a dye which in your opinion is the key to bright Salor reds
Even this will not be very successful when one wants to achieve very saturated shades (thus using a very long process).Quite understandably, since the decarboxylation of pseudo-purpurine is only slowed down in a cold dye-bath
not stopped.

To check whether and how the various components of madder change shade when using tin salt instead of alum as a mordant is surely better done by
separating the dyes quantitatively, (various physical processes including LC are suitable, as you know), but much simpler qualitative tests (a «dip test» for example) give reasonably accurate indications too.

University papers dealing with various mordants, including calcium-, magnesium- and tin-salts: I suggest googling, «metal complex of alizarin», «fastness of natural dyes», « alizarin/calcium/ aluminum metal complex» and «structure of turkish red». This should yield a pretty large number of leads to follow and further expand from. A copy of the «bible» written by my former competitor (and nevertheless outstanding analytical chemist ) Schweppe, would give you some mileage too.
Besides, calcium complex of dyes and pigments had their (short) period of glory around 1910-1930. Does "Fanal" ring a bell?

Well, that’s it I guess.

Best regards
Pierre