C.I. natural red

Some natural dyes are coming back into use and amongst these is one called Dragon s Blood (C.I. Natural Red) which consists of the flavenes dracorhodin (134) and dracorubin (135). 

Rubia tinctorum L. (Rubia tinctoria SALISB.) (C.I. Natural Red 8)... 

Result The warp and filling threads are composed of natural silk, grounde with the lichen dye orchil (C.I.Natural Red 28) and dyed with madder (Rubia tintorum). 

The glacial acetic acid extract can be stained by indigo (C.I. Natural Blue 1) in a blue shade, by berberine (C.I. Natural Yellow 18), the only basic natural dye, and sometimes by madder (C.I. Natural Red 8) in a yellow shade. 

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. 

Dyeings with orchil (C.I. Natural Red 28), the natural dye obtained from lichens, become colorless when they are treated with sodium dithionite the original magenta red shade returns when they are aired. 

Testing of Red Natural Dyeings. Of the red dyeings made with natural dyes, those produced with safflower (C.I. Natural Red 26) can be identified in the extraction tests with water and with ammonia (colorless), as indicated earlier. Dyeings with sandalwood (C.I. Natural Red 22) can also be identified at this early stage because they turn dark violet when they are boiled in ammonia. When they are washed with water, the original red shade returns. 

If the violet dyeing becomes only somewhat paler when treated with 102 sulfuric acid, the specimen is washed out with water and vatted with sodium dithionite and ammonia. If the dyeing then turns yellow and is reoxidized in the air to a blue, this dyeing is one with alkanna (C.I. Natural Red 20) on alum mordant. 

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... 

The threads on the face of the carpet that have faded (because of their moderate lightfastness) become colorless when they are vatted with sodium dithionite and ammonia, and they turn magenta upon subsequent reoxidation in the air. This dyeing is, therefore, one made with orchil (C.I. Natural Red 28). This dye was known as French purple , and very often it was used in tapestries in the 16th-19th centuries despite its poor lightfastness. 

Materials. The wool fabric was a plain-weave worsted wool, style 6561, from Burlington Industries. The silk fabric was a degummed silk crepe, style 601, from Testfabrics, Inc. The dyes were >95% pure and were from the following sources alizarin (C. I. Mordant Red 8) from Aldrich Chemical Co. brazilin (C. I. Natural Red 24) from J. T. Baker Chemical Co. and carminic acid (C. I. Natural Red 4) from H. Kohnstamm Co., Inc. The five reagent grade metal salts used were aluminum potassium sulfate, stannous chloride, cupric sulfate, ferrous sulfate, and potassium dichromate from J. T. Baker Chemical Co. 

The flavonoids, derivatives of flavone (353) and of isoflavone (354), are widely distributed among plants of many kinds. They provide colour (from pale yellow to orange) in flowers and their potential as dyes is being revived now that awareness of the toxicity of some synthetic dyes is increasing, for example morin (355 C.I. Natural Red) is one of many possible hydroxylated flavones with dyeing properties. 

Carniinic acM (7-C-glucopyranosyl-3,5,6,8-tetra-hydroxy-1 -methyl-anthraquinone-2-carboxylic acid, E 120, C. I. natural red 4, C. 1. 75470). 

Laocaic adds (C. I. natural red 25). A group of red an-thraquinone pigments excreted from glands of scale insect species (e.g., Laccifer lacca, Tachardia laced) living in South East Asia on Butea monosperma (Fabaceae) and Zizyphus mauritiana (Rhamnaceae) as host plants and used as pigments for cosmetics and foods. 

CA Index Name Orcein Other Names C.I. 1242 C.I. Natural Red 28 Merck Index Number 6863 Chemical/Dye Class Phenoxazine... 

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