Lightfastness of Dyes – an Historical Perspective

A dear friend recently put a small booklet into my hands: Fast Dyeing and Dyes by James Morton.  It is the bound proceedings of a lecture that Morton delivered to the Royal Society of Arts in London, 1929. 

Morton’s father, Alexander Morton, founded the weaving company of Alexander Morton & Co, in England in the late 19th century.  The son, James was trained as a chemist and specialized in the use of permanent lightfast dyes for cellulose textiles. In the narrative, James recounts work that he  accomplished in 1903 to develop a palette of lightfast dyes for textiles. It was an interesting time in the development and use of textile dyes.  Up until the second half of the 19th century, natural plant and insect dyes were the source of all textile colors, but by the early 20th century chemical dyes were quickly replacing the natural dyes in industry. 

Morton’s company specialized in producing woven furnishing fabrics for curtains, carpets, upholstery and tapestries.  He spoke of observing one of the company’s tapestries in a store window display. After only a week’s time, the colors had faded dramatically. This led him to question the dyes they were using. He commandeered his family greenhouse (which had previously contained tomato plants) to set up a series of lightfastness tests. He tested fabrics from his own company as well as those from others. The results he described as “staggering”. Even deep shades of color applied to expensive fabrics became almost white after only a week’s time. He made detailed notes and documented each sample. 

After making these careful observations, his goal became one of identifying a few colors (produced by chemistry) that could be relied upon and that performed well. Morton believed that even a limited range of colors that would remain on the textile over time was far preferable to a large palette of color that would degrade quickly. The company trademark Soundour was born – a combination of the word “sun” and the Scottish word “dour” meaning stubborn or hard to move. He identified the Alizarines as “good friends” which kept their shades. This was a class of chemical dye, based on the synthetic manufacturing of alizarin, the primary red colorant in madder root.  In 1869 it was the first natural dye to be produced synthetically. Colors derived from minerals were acceptable as sources for light browns.  Indigo was deemed unsatisfactory for longevity on cellulose but Indanthrene vat dyes, new to the market, served as a good source of yellows, blues and greys. (These are the same vat dyes that I previously used in my own work.)

All the chosen chemical dyes were tested thoroughly, both in the greenhouse and on rooftops in India, where the sun was hot and intense and the humidity was high. The result was a carefully chosen palette of color that could be advertised as reliable and be priced accordingly – significantly higher priced than other fabrics on the market. The goal was to have colors that would last as long as the textile itself.

What strikes me about this story is the recognition of lightfastness being of value at a time when there was such excitement about the ability to easily produce almost any color through the use of the new “chemical” dyes. Morton changed the industry’s awareness of and approach to the use of synthetic dye color.  Interestingly, he stated that “Some manufacturers questioned the wisdom of raising the standards so high…”

I can’t help but see a parallel to today’s re-discovery and excitement about natural colors. That excitement often causes a “blind spot” when it comes to objectively looking at the longevity of some dyes. If the experience of making color is the singular goal then it doesn’t matter so much how long the color will ultimately last, but if there is a customer with an expectation that the color will last as long as the textile, then colorfastness is a different and critical matter. 

Professional natural dyers have made decisions over the centuries to provide customers with the best quality colors possible. The Dyer’s Handbook: Memoirs of an 18th -century Master Colourist, by Dominique Cardon makes the following statement about testing for “false” colors: “It is not enough for the dyer to have acquired knowledge on the drugs that are necessary to him and on their properties, and to have managed to employ them with success. He must also distinguish the fast colors from the false ones…”

All dyes fade – that’s a fact. And all textiles will deteriorate. My colleague, Joy Boutrup, says that acceptable fading of a dye results in a lighter version of the original hue while the integrity of the original color is maintained: a lighter indigo blue, a softer madder red etc. – not an “ugly beige color” that has no relationship to the original. And the ultimate goal is that the color last as long as the textile.

My own current study of “fast” and” fugitive” dyes on wool yarn: Indigo over-dyed with cochineal vs. logwood. Original colors (left) and after 3 weeks of direct sun exposure (right)
“Fast” and” fugitive” dyes: Cochineal vs. Brazilwood. Original colors (left) and after 3 weeks of direct sun exposure (right)