To accompany her experiment in The Hunterian Art Gallery, Katie McClure, a PhD candidate at the University of Glasgow’s Kelvin Centre, discusses the vulnerability of historical textiles to fading and her research into ‘unfadeable’ dyes made in Scotland.
Have you ever noticed that some rooms in museums are very dark whilst others are rely on large windows for illumination? Have you wondered why textiles are usually in the darker rooms?
Some historical textile dyes are very chemically sensitive. This means that exposure to radiation (from the sun or indoor lighting) can cause their molecules to break down. These chemical transformations can cause their colours to change or disappear.
Museums and galleries have to bear these sensitivities in mind when displaying textile artefacts. This means weighing up decisions between access and visibility of collections with potential irreversible damage.
Usually, by controlling lighting (using low-energy bulbs and covering or filtering windows), even sensitive textiles can be displayed for a limited amount of time without noticeable changes in colour.
However, different types of dye can tolerate different amounts of light exposure – so each textile has individual requirements.
Fading Tests
There are a few different methods for studying how textile dyes fade under exposure to light. Some methods use very intense lighting conditions to accelerate the degradation of dye molecules.
Other methods involve exposing dyed textiles to real, everyday lighting conditions over long periods of time and monitoring the colour change regularly using scientific analysis.
These natural ageing tests take much longer (typically 3-12 months) but are more representative of what a historic object might really experience in storage or on display.
The problem with these tests is that to understand how textiles fade, we have to let them fade. For most methods, this means that they can’t be ethically applied to real historic objects because they would cause irreversible visible and chemical changes.
For this reason, modern-day reconstructions of historical dyed samples are often made. These can then be experimented upon without the risk of damaging a historical object.
Making these reconstructions involves deciphering historical dyers literature to recreate their recipes.
One such study on a selection of important twentieth century dyes is currently underway in the Hunterian Art Gallery, with four test panels placed in various lighting conditions.
One panel is placed in a dark cupboard (unexposed), the second in an unfiltered window, the third in the museum stores, and the last in a low-light space in the art gallery. These reconstructions will be measured every two weeks for a number of months to assess whether their colours fade over time.
The ‘unfadeable’ dyes under study
The dyes being analysed by this experiment are an important and understudied group of synthetic dyes, the anthraquinoid vat dyes, first discovered in 1901.
In the 45 years prior, the textile dyeing industry had undergone major changes – beginning with William Henry Perkin’s discovery of the first synthetic dye in 1856. Before this, all dyes were derived from natural resources (plants, animals and lichens).
Perkin’s discovery birthed a new industry of chemists trying to make new exciting textile dye colours in the lab. These lab-made products could be produced more cheaply and reliably than natural dyes.
However, many early synthetic colours faded quickly when exposed to light or when washed, leaving manufacturers and consumers dissatisfied.
In 1903, a weaver and businessman from the Ayrshire village of Darvel resolved to fix this problem after he saw the faded state of his tapestries in the window of Liberty, the luxury department store in London. In 1929 he recalled:
“…they had changed so radically, that I scarcely recognised my own handiwork. Certain colours had gone so much that the balance of my schemes had been completely upset, and I went in to enquire what had happened to these goods. I was told they had only been in the window for about a week.”
– Morton, J., ‘A History of Fast Dyes and Dyeing’, Royal Society of Arts, 1929
Morton set about testing as many commercially dyed fabrics as he could by exposing them to sunlight in his home greenhouse. Very few passed his tests, with most fading significantly after just a week or two. The best performing dyes by far were the recently discovered anthraquinoid vat dyes from Germany.
The anthraquinoid vat dyes were expensive and complicated to apply so were yet to find a market, but Morton recognised their potential. He built his ‘Sundour’ (stubborn to the sun) brand, based in Carlisle, around their fade-resistance.
The company sold their Sundour fabrics with a guarantee that the colour would last as long as the textile itself. These new fabrics impacted public perception around the longevity of textiles.
During the First World War, Morton began making these dyes in-house – first in Carlisle and then in their own dedicated site in Grangemouth, which later became ICI. Between these two sites several new colours were developed. The most important was Caledon Jade Green, the first fade-resistant green dye for cotton.
The dyes were used in everyday household fabrics; book covers; military supplies; and artist-designed Arts and Crafts and Modernist textiles, many of which are in museum collections today.
This fading experiment tests three important anthraquinoid vat dyes and compares them to indigo, a well-studied historic dye with a reputation for good stability.
It seeks to understand whether these textiles are as ‘unfadeable’ as the primary sources say, and to ask what their fade-resistance means for collections care.
To hear more about Katie’s research on the anthraquinoid vat dyes, visit her Linktree.
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