Red insect dyes

The red insect dyes from Dactylopius coccus COSTA (American cochineal), Kermococcus vermilio PLANCHON (kermes), and Kerria lacca KERR (lac dye) can also be readily distinguished by thin-layer chromatographic comparison. 

Figure 9. TLC comparison of the red insect dyes in the Karabagh carpets, figures 7 and 8, after dissolving the dye extracts in different organic solvents. 1 and 2, extracts of the Karabagh carpet (figure 7) 1, soluble in ether 2, soluble in ethyl acetate + methanol 3 and 4, extracts of the Karabagh carpet (figure 8) 3, soluble in ether 4, soluble in ethyl acetate + methanol 5 and 6, extracts of Armenian cochineal S, soluble in ether 6, soluble in ethyl acetate + methanol 7, Polish cochineal 8, American cochineal 9, kermes 10, laccaic acids (XXVIII - XXXII) 11, erythrolaccin (XXXIII) 12, deoxyerythrolaccin (XXXTV).

Dyeings with the red insect dyes cochineal (C.I. Natural Red 4), kermes (C.I. Natural Red 3), and lac dye (C.I. Natural Red 25) bleed an orange shade. After shaking with ethyl acetate and pentanol (1 1), the dye solutions can be used for TLC comparisons. 

Hydroxyanthraquinone from Red Insect Dyes Figure 3 shows how to distinguish among the three red insect dyes cochineal (C.I. Natural... 

Table II. hRf Values of Hydroxyanthraquinones from Red Insect Dyes...

Figure 3. TLC of hydroxyanthraquinones from red insect dyes. I, cochineal 2, lac dye and 3, Kermes vermilio.

Kermesic acid an anthraquinone, m.p. 250 °C (d.), which occurs naturally as a bright red insect dye. It is structurally closely related to Carminic acid (see) it possesses the identical structure of a tetrahydroxyla-ted methylanthraquinone carboxylic acid, but there is no C-glycosidic glucose on C2. K.a. makes up 1-2% of kermes, the dried bodies of female scale insects Kermococcus ilicis. Kermes is one of the oldest known dyes and was used in ancient times as a scarlet mordant dye (Venetian scarlet), It was supplanted in the 16th century by cochineal. 

Oaks and especially Quercus coccifera are host plants for Kermes ilicis, producing the red kermes pigment. In Asia, the Laccifer lacca insects that grow on trees like Schleichera oleosa, Ziziphus mauritiana, and Butea monsperma are the sources of the red lac dye. - ... 

Schweppe, H. (1989), Identification of red madder and insect dyes by thin layer chromatography, in Historic Textile and Paper Materials II Conservation and Characterization, ACS, pp. 111-219. 

Identification of Red Madder and Insect Dyes by Thin-Layer Chromatography... 

Besides indigo and Phoenician or Tyrian purple, the red madder and insect dyes were of particular importance for the dyeing of textile materials in earlier centuries. These dyes were used to produce the highly prized red and violet dyeings with outstanding fastness to light and... 

When the historic textile material to be investigated contains a red that has hardly faded, we should start by testing this red dyeing, because this is the simplest and quickest way to obtain a result. In the first place, we need a smaller sample for the identification of red anthraquinone dyes than for identifying yellow flavone dyes, and in addition, it is then usually possible to identify the dyer s plant or dye insects that have been used for the red shade. 

Significant progress has recently been made in the identification of red madder and insect dyes on historic textile materials (2,7,8,9). As the most of these natural dyes are mixtures, chromatographic methods such as TLC and HPLC are the preferred techniques. 

Figure 12. Identification of the insect dyes in the Sicilian coronation robe (figure 10) and in the Tunicella (figure 11) by TLC comparison. Solvent butanone-2 - formic acid (7 3) 1-3, extracts of the three samples of dyeings of the coronation robe 1, red silk 2, lining material, filling threads 3, lining material, warp threads 4, red silk from the border material of the Tunicella 5, kermes 6, Polish cochineal 7, American cochineal 8, laccaic acids from lac dye.

Figure 7 shows a piece of 16th century Mameluke carpet from Cairo. The red threads in this carpet were dyed with the insect dye lac dye (C.I. Natural Red 25). The mordant was identified as aluminum and a small amount of iron and copper compounds. However, as copper also was... 

In the past, it was assumed that Tyrian purple was used for dyeing this coronation robe. However, Max Saltzman (University of California, Los Angeles) doubted that it was a purple dyeing. He obtained a small piece of a thread from the coronation robe in the Weltliche Schatz-kammer of the Vienna Hofburg. In my laboratory and in that of Max Saltzman, by means of several color reactions, we were able to prove that this dyeing was produced with a red insect-derived dyestuff. 

NATURAL DYES The red dragonfly may be one of several insects that produce the red cochineal dye, a tricyclic compound with many multiple bonds. 

Carminic acid Aluminum and calcium salts give red/purple dyes called carmine derived from the cochineal insect... 

Raw lac is first treated to remove water-soluble carbohydrates and the dye that gives lac its red color. Also removed are woody materials, insect bodies, and trash. It is further refined by either hot filtration or a solvent process. In the heat process, the dried, refined lac is filtered molten through cloth or wine screens to produce the standard grades of orange shellac. In the solvent process, lac is dissolved and refluxed in alcohol solvents, filtered to remove dirt and impurities, and concentrated by evaporation. The lac can be further decolori2ed in this process to produce very pale grades. Bleached shellac is prepared by treatment with dilute sodium hypochlorite and coalesced into slabs. 

Cochenillen-farbstoff, m. cochineal dye. rot n. cochineal red. -scharlach, m. cochineal scarlet, -schildlaus, /. cochineal insect. Cochenillesaure, /. cochenillic acid. 

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