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Salon du Tapis d'Orient

The Salon du Tapis d'Orient is a moderated discussion group in the manner of the 19th century salon devoted to oriental rugs and textiles and all aspects of their appreciation. Please include your full name and e-mail address in your posting.

The Natural Colors Itch

by Vincent Keers

I was reading an old study book from the Textile School.  There I found some different chemical dyes, like: basic-, acid-, salt-, mordant-, vat-, ice dyes.   I.G. Farben, Bayer, etc. all made their own special dyes.  The book is from 1949, so the text deals with a time frame that can be of interest: 1857 up to 1940.

Most old rugs that we see in our everyday life are from this time frame.  And the most heard claim nowadays is: All natural dyes.

I'm taking the position that if anyone claims "all natural dyes" he must have been living his life in another world. The "invention" of chemical dyes in the turmoil of industrialization had its impact.  So, what to do?  We must find a way to establish some kind of basic standard per color.

Color is the reflection of light. What is light?  Light is energy formed by electromagnetic radiation; radiation in the form of waves.  Each colour has it's own wavelength.  Light is all possible colors (all wavelengths) within the range, approximately 400 to 700 nanometers (violet to red, respectively).

White is all colors, the total spectrum (from red up to violet) is reflected.    Black is 0; nothing is reflected, all is absorbed.

What is color?  Colour is the result of reflection of electromagnetic radiation.  So all the colors are already available in sunlight that reaches a surface.  The pigmented surface of an object reflects some colors and absorbs some colors.
A lemon is yellow because the skin's molecules only reflect the yellow part in the total light spectrum.  All the other colors are absorbed, and do not reach our eyes.

The retina (the light detecting part) of the human eye has three kinds of cones.  One kind that is most sensitive to red light, one most sensitive to green, and one most sensitive to blue.  Depending on the properties of a surface, different percentages of red, green and blue light are reflected.  So the cones receive the reflected combination and are stimulated accordingly.

What our brain does with that information can be different from person to person.  Even the left and right eye can make different combinations.

I think natural impurities and the cross contamination between colors in the spectrum is why we like natural colors better.  The molecules in the pigment used to make a natural dye are never precise.  For instance, how pure was natural indigo?  It's been said that synthetic indigo was better, more pure.  But the more perfect the indigo, the less red and green our cones receive.  If our cones receive less red and green because it's pure blue, the blue will act like black versus white.

About the color orange:  in the color spectrum we can see that orange has a very narrow wavelength range.  Maybe the reason that we do not like orange in our rugs is because this orange color is difficult to get with natural (not pure)
ingredients and easy to produce synthetically.  A dye master could have had a lucky hand in his color-composition, but the change is only 0.25% to get pure orange and 1% to get a greenish orange and 1% to get a reddish orange.

In the end, all we think we see is only in our mind.   An orange isn't orange.  It reflects orange to our eyes, the cones send the information to our brains and we name it orange.   I'm no specialist on this subject. That's why I'm trying to get some standard by which I can differentiate between natural and chemical dyes.  I think natural dyes mingle better because of the natural cross contamination.  The modern quest for natural dyes, perfection (lab conditions), may be too perfect.   Perhaps that's why most new natural colors clash.

We must find a way to establish some kind of basic standard for natural color.  A silly notion?  Maybe, but all of you must have some basic standards by which you try to distinguish chemical from natural dyes.  I hope some experts out there are willing to show us their expertise/experience on this subject.