The Peter Quiz
Joseph Crea Joseph.Crea@worldnet.att.net
Mon, 15 Feb 1999 04:05:16 +0000 (00919073116, 19990215040516.BZGL18996@LOCALNAME)
Hello, Joe!
At 06:54 PM 2/14/99 EST, JAlw@aol.com wrote:
>In a message dated 99-02-14 18:37:08 EST, you write:
>
><< Or another way to put it: the most accurate translation of both words, in
> order to translate what they would have DENOTED at the time they were used
>might
> be "deep red-purple". And since Crea seems to have sufficient authority on
>the
> subject that there I will let rest unless and until I see some information
>from a
> reliable source to the contrary. If the words are synonyms, at the time and
>place
> they were used, then there simply isn't a discrepancy worth arguing about, at
> least not to me. >>
>====================
>Joe Alward:
>
>First, thanks for the well-written clarification of Crea's point.
>
>However, you said, "And if it was the SAME color", but don't make it clear
>that you or Crea are not just conjecturing that they were the same color, but
>just called by different names. Did I overlook something?
CREA
Yep, human curiosity (and the stubbornness of some quasi-Luddites).
While Tyrian purple and kermes scarlet are no longer commercially used,
there is still a small but thriving arts & crafts community which actually
prefer the natural dye stuffs over the synthetic. As a result, there are
works which include color plates illustrating something of the range of
colors attainable with such natural dyes.
While much of the material has been done by anti-technology advocates,
strangely enough, dye chemists (from time to time) also poke their noses
into these most unlikely corners. According to C.E. Pellew in his 1928 work
__Dyes and Dyeing__, sometime around 1908 a German dye chemist named
Friedlander spent his summer in Naples collecting approximately 12,000 Murex
snails in order to obtain a useable quantity of Tyrian purple. Upon
extraction he obtained approximately three-quarters of a gram of the "pure"
dye. Upon analysis it proved to be 6,6 dibromoindigotin. His interest had
been aroused by his earlier synthesis of thio-indigo Red B, but the analysis
showed that what he had synthesized was not Tyrian purple. Subsequently
Tyrian purple was successfully synthesized and produced for a short period
of time, but it offered no real advantages over the other contemporary
synthetic violet and purple vat dye stuffs and soon disappeared from the
marketplace.
More than half a century later, in 1971, another German dye chemist,
Helmut Schweppe, experimented with both natural and synthetic (pure 6, 6
dibromoindigotin) Tyrian purple and published his findings. The color
plates which accompanied his article, "Testing of Old Textile Dyeings",
__The B.A.S.F. Review__ no. 26, pp 29-36, show something of the range of
colors which can be achieved with this material. Since all the natural
material consisted of both indigotin and 6,6 dibromoindigotin, it was found
that the higher the percentage of the brominated derivative, the greater the
tendency toward a reddish purple or what was termed "scarlet".
The other dye, "scarlet", is essentially an anthraquinone derivative
named kermesic acid (C18-H11-O9). Unlike "purple", there is only a single
dye stuff involved here, but it is essentially polychromic, with the actual
colors produced depending on the presence (or absence) of various metallic
ions derived from the dye-kettle (typically iron, copper & tin), the use of
mordants like alum, and the pH of the dye bath (think of litmus paper, for
example). Color plates which show something of the range of colors
available can be found in such works as Rachel Brown's __The Weaving,
Spinning, and Dyeing Book__ (Knopf, 1983, 2nd edition, 0-394-71595-0).
Again, the range of colors includes the reddish-purples which are also
typical of some shades of Tyrian purple.
Hope that this helps.
With Mettaa,
Joseph Crea
<Joseph.Crea@worldnet.att.net>