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-   -   Notes on indigo and green abrash (http://www.turkotek.com/VB37/showthread.php?t=3576)

Filiberto Boncompagni2 April 16th, 2016 08:59 AM

Notes on indigo and green abrash
I had an exchange of opinions with Pierre Galafassi on the age of a Caucasian rug posted in the Show and Tell section. I think it is interesting to keep his comments here for future reference, independently of the rug in question.

(Pierre): I would guess that this rug is fairly recent, say 50 years or less, since the green, either has been dyed on the basis of modern wool dyes (most probably of the 1/1 Cr complex family) or, if Indigo was still the base, then a modern dyeing machinery was used for both the indigo dyeing and the yellow dyeing.
There is much too little abrash for such a shade: Sure, Imperial manufactures of the Safavids or Moguls, for example, or perhaps a good industrial dyehouse of the end of nineteenth century Russian era in Caucasus, could have obtained a nearly abrash-free green with indigo too, but only if the dye master would have handpicked dyed skeins with quasi identical indigo blue shade, from the extensive stock of skeins such a manufacture probably would have carried.

(me): Well, it seem a rug of the first quarter of XX, so it should be a "kustar" product and they DID give to weavers dyed wool in the kustar organization, it seems.
So, would it fit with your judgment?

(Pierre): Perhaps yes.

I have noted that Indigo dark blue, and bluish black, became very frequent in Caucasian rugs by early XX century, assuming that Azadi’s / Kerimov’s « Azerbaidjanisch-Kaukasische Teppiche » book is representative for the period.

Probably because synthetic indigo became so much cheaper than the natural stuff.
Expertise with this difficult dye must therefore have existed in Kustar dye houses.

It seems also indeed possible, as you suggest, that the Kustar organization regrouped the dyed skeins of each shade in uniform lots before dispatching them to the weavers. Russians were rather rational Europeans after all, well some of them at least. Lack of abrash might have been a key requirement of European customers back then.

I am presently browsing through my Kerimov copy and, while much less frequent than dark blues shades, dark green is well represented too. However, imho, more in borders and in medium/small-size motifs. The definition of the pictures in my book does not allow to make a judgment on the abrash though.

Perhaps a last point about this indigo / green discussion.
What most differentiates an abrash in green shades made with indigo from an abrash with most other shades dyed with other natural dyes (and without indigo), is a strong micro-abrash (from one knot to the next one) in addition to the usual macro-abrash (differences of shade between full areas, from line to line for example) which is of course frequent on cottage or village rugs.
- Macro-abrash being evidently due to the facts that under these basic dyeing conditions the dye concentration can’t be measured and reproduced well from batch to batch.( No precise scale in use, heterogeneous dye content of the dried plants or insects, etc…) , that each batch is small and not always sufficient for providing all the dyed wool necessary for a given rug, that the dyeing properties of the wool itself can vary from batch to batch (spring wool vs. fall wool, wool taken from different body parts of the sheep, more or less well de-greased wool, various degree of whiteness of the wool, etc…) and that the basic dyeing vessels and auxiliary material make it difficult to expose each skein to the same dyeing conditions batch to batch as well as in the same batch (only manual agitation of the dye-bath, no thermometer, etc…
- While micro abrash is due to the peculiar behavior of the indigo dye in its typical dip-dyeing process. In particular to a premature formation of some pigmentary (insoluble) dye in contact with air (which is nearly impossible to avoid in pre-industrial dyeing vessels) which leaves, locally on the skeins surface, « scales » of insoluble indigo pigment which « reserve » the fiber underneath it and thus block the access of this little places to the soluble form of the dye with is supposed to penetrate it and dye it. Thus leaving, after the final wool washing and elimination of the pigmentary surface scales, much paler and yellower random spots on each skein.

While the normal macro abrash can be quite easily limited by sorting and grouping lots of skeins with similar shades, such an operation is much more difficult with micro-abrashed wool since the spots most probably affect all skeins in all dye batches.

Many thanks to Pierre,

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