your essay is excellent, clear and perfectly documented. We do need
scientists on board of Turkotek, I am sure that Steve emphatically shares
I like very much Moshe Tabibnia's
scientific approach and do wish that all important and serious dealers
would emulate him, even at the risk of contradicting rug lore from time to
Your conclusion that the Chinese/Ningxia dyers perhaps
preferred sophisticated, delicate shades and were therefore ready to
compromise with borderline lightfastness, when necessary to achieve them,
seems highly credible to me.
It could also be that these dyers were
more focused on dyeing textiles (silk for example) and less sensitive to
the specific requirements of wool rugs (perhaps a secondary market for
them), in terms of resistance to light-induced fading.
As far as
the rarity of safflower yellow
on rugs is concerned (while much
used on textiles according to your sources), one could suggest that the
Chinese / NingXia dyers were perfectly aware of its obvious, extremely
poor lightfastness and judged it much too poor for rugs. Besides, the
beautiful safflower red
(which was known to Tibetans, thus probably
to their Chinese-and Uyghur- neighbors too), has a much better
lightfastness than the yellow component, but still an inferior one to
madder-, lac- or cochineal (mordant-) dyeings.
That gromwell was
found by the Bergamo team in purple shades is very interesting. Roots from
this botanical family give very strong shades on wool, ranging from dull
purple to purplish- or bluish grey and even black shades. However this
strong dye must be applied either from a fatty emulsion or dispersion in
water (no piece of cake), or from an alcohol/water solution (a trifle
stronger than rice wine if possible (it would enhance the dyer's mood if
it were more tasty too
), but this recipe surely was suspect to
pious ulemas. The Bergamo finding might indicate that Chinese / NingXia
dyers were not necessarily Muslims (Uyghur etc..).
If the Bergamo
scientists have serious clues that a lac (mordant-) dyeing is showing an
abnormal fading, I would suggest to them a determination of the mordant
(by plasma spectra for example). Lac (lacca´c acid) gives a lightfast
(Bordeaux-wine-) shade on wool when mordanted with alum, but I am not
aware that the lightfastness with other mordants has ever been tested. It
is perfectly possible that lacca´c acid would have poor lightfastness when
mordanted with these metal ions, or of course when applied un-mordanted.
The dyers may have accepted, again, what they saw as a nicer red shade
despite its poorer light fastness. Tin- and zinc salts come to mind
(copper and iron can be excluded, because they lead to brownish shades
with lacca´c acid).
Vis-Rs is not a very selective method, even
when backed by a complete data-base of reference curves and the ad-hoc
software. As you rightly mention, it is only a useful auxiliary
Did your Bergamaschi friends already play with the
fluorescence methods which are routinely used for analyzing pigments in
old paintings by labs working with Museums? According to literature the
fluo emission spectra of various mordanted madder pigments, for example,
are quite specific.