Thanks for the flowers, I am
1.1. Yes, indeed wool can be
«whitened» (with so-called «optical brighteners»: blue-violet fluorescent
molecules which make a yellowish textile seem whiter) and wool can be
«bleached» (As a first step by properly scouring the wool, then, if
required, by extracting and destroying its natural yellow-ivory tint with
a chemical process).
Actually, a large percentage of the wool
production is bleached before dyeing.
Although some natural optical
brighteners are known, I do not know whether they ever were used by our
ancestors on rug wool. I doubt it though .
1.2. I cannot comment
much on «wool fermentation». Actually I did not believe Dr. Bieber’s
theory (Dr Böhmer seems skeptical too (*)), until a friend, owner of a
wool-dyeing and carpet-weaving company and expert user of natural dyes,
managed to convince me of its validity. Apparently, the old trick was
never completely forgotten by some Turkomans. Amazing!
The wool is
left in a vat with some alum and enough acidity to avoid fouling, during a
week or more, at ( Afghan summer-) room temperature. Some fermentation
takes place and apparently does open the wool scale structure, making a
subsequent «cold» mordant dyeing possible. «Cold» meaning some 50° or 60°
C, I guess. The dyeing time is obviously much longer than when using a
conventional process. Clearly it has a favorable impact on both shade and
strength (Shade of madder red is quite sensitive to dye-bath
2. With «small» and «bulky» dyes, I was referring to
the dimension of their molecule. In order to obtain a true dyeing the dye
must penetrate into the fibre (just sitting on its surface would never
give the necessary «fastness». For example light-, wet-, rubbing- or wash
fastness). Unfortunately, the channels through which the dye must diffuse,
in order to penetrate the wool, are rather narrow compared to the size of
some dyes. To use an image, some dyes are like bikes and others like
20-ton lorries: guess which one is quicker in the narrow, crowded and
winding streets of Samarkand ? (I am positive: there are bikes in
3. I fully agree, it must be a rare occurrence: The
main natural dyes used for rugs (Alum mordanted madder, insect reds and
flavonoid yellows, as well as the vat dye indigo) are good dyes, perfectly
suited for any normal usage of a rug.
Madder and insect reds probably
do bleed in some rare accidental cases (traces of running red can be
spotted because the eye is so sensitive to it).
Judging from their
chemical structure one would expect the main natural yellows (mostly alum-
or tannin mordanted flavonoid dyes, like luteolin) to bleed a trifle more.
However the small quantities of yellow which can be expected to bleed,
even under rather unusual rug conditions, will probably nearly always be
mistaken for natural variations of the wool shade or dirt.
4. I am
not familiar with the brand name RIT. Some modern wool dyes (leveling acid
dyes) are not suitable for rug wool, they are too keen to bleed. To make
quite sure that a dye is ok, one can use a very simple test. Make a
sandwich of cotton, (deep-) dyed wool, un-dyed wool and cotton again, wet
it, press it, put it in a small plastic bag, near the heating (say at
around 25-30°C, no more!! ) and forget it there for a couple of hours. If
the colored fibre has not bled at all, the dye is probably OK. (Madder or
chrome dyes would not bleed at all under these conditions).
Koekboya. Dr H Böhmer.