Prevent dyes and a cultural tradition from fading

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This article originally appeared in Yale Engineering Magazine.

Each work of art presents its own set of challenges for restorers and conservators, not the least of which is curbing the effects of time. To that end, a device known as a microfading tester (MFT) gives art curators a much better idea of ​​where and how long they can safely display a particular work before a irreversible discoloration does not occur. At Yale, researchers are working to make this technology not only more accessible to museums around the world, but as a way to preserve cultural heritage in other parts of the world.

Developed by Paul Whitmore, now retired director of the Aging Diagnostics Lab at the Yale Institute for Cultural Heritage Preservation (IPCH), the MFT device predicts the rate at which dyes, such as pigments and dyes, will fade under normal gallery display. . Using fiber optics, the device shines an intense beam of light onto a microscopic patch of material, measures the reflected light, and triggers the photochemical reactions that would cause light-sensitive colors to fade. Every minute the light shines on the material equals approximately one year of aging. Researchers typically use it for up to 5 minutes at a time, allowing them to see five years into the material’s future.

MFT allows us to monitor the fading of dyes or pigments in real time, predicting fading behavior under gallery conditions,” said Katherine Schilling, associate researcher in chemical and environmental engineering and associate conservation researcher at the ‘HICP. Since the microfading test leaves essentially no trace of faded color, objects can be quickly examined for lightfastness, that is, how long dyes can withstand the effects of fading. This helps determine future storage or display needs.

The software can measure how long specific dyes can resist the effects of fading.

With the MFT, researchers can obtain information about the light sensitivity of everything from sloth fur and bird feathers to paintings, drawings, photographs and textiles. More recently, IPCH used the technique to test dyes used in rugs from an indigenous weaving community in Afghanistan, supporting a collaboration between Yale researchers and a non-governmental organization (NGO) that supports Afghan artisans, mostly women. (Due to political instability in Afghanistan, one representative requested that the name of the NGO not be used).

The project aims to help Afghan weavers find the best possible dyes, in part to preserve an age-old tradition, but also to give Afghan women a better chance of earning a decent income. Before the August 2021 takeover by the Taliban, it was known that there were around 1 million carpet weavers in the country. Even under the best conditions, weaving is not an easy way to earn a living.

We have partnered with a dynamic organization with the ability to work directly in regions where weaving and other traditional art forms have been decimated by commercial or political interests, and now war and famine,” said Alison Gilchrest, Director of Applied Research and Outreach for the HICP. . “These are communities where the skills and ways have been passed down to families for generations, and they deserve an opportunity to thrive.”

The NGO representative noted that the export of handicrafts has become a fast-growing industry, partly because people are buying more and more with sustainability in mind.

We work with lots of retail partners who know their customers and know exactly what kind of styles they like,” she said. “We need to make sure that we can present them with a product that works, based on their very serious business standards, and one of those concerns is fading away. This happens in carpets and textiles by light and touch. If you want to create high value jobs for women in rural Afghanistan, you better be able to create a product that doesn’t fade.

At the IPCH lab on Yale’s West Campus, researchers work with a large dye-sampling mat provided by the NGO. In a grid of 190 squares, the sampler presents patches of all the dyes used by the weavers.

Dye sampler mat
The dye-sampling mat provided by the organization consists of small squares colored with different dyes, each commonly used by Afghan weavers.

We systematically work through the sampler to come up with recommendations for which colors are more likely to fade,” Schilling said. “Given the range of options, weavers can then make substitutions and hopefully still achieve a similar aesthetic effect.”

Two students are contributing to the Afghan Rug Project, Vanessa Lamar, a physics major, and Daniela Flores, a chemical engineering major. Schilling prepared students for this work by creating an independent study of dye photochemistry during the spring semester. Using the MFT instrument, they measured the lightfastness of various materials. Lamar said there was a bit of a learning curve in operating the microfading device, but his background in physics was a big help. At the end of the semester, she decided to continue the project all summer.

Vanessa Lamar '23 uses the MFT device to predict how quickly colors in a given material will fade
Vanessa Lamar ’23 uses the MFT device to predict how quickly the colors of a given material will fade.

I never thought I would be able to do something that combines my interest in art and the humanities with science, and this job gives me the opportunity to explore that world,” she said. declared. “Even though I usually work with numbers and machines, it’s good to know that the work I do has a human impact.”

The HICP researchers also plan to expand the use of the MFT, a goal that calls for a redesign to make it less expensive and more usable for museums around the world. The lab contains a few versions of the MFT that have been made since Whitmore invented it in the 1990s. It’s time, the researchers say, for a more thorough overhaul.

The best way to honor the legacy of the project is to build on its success,” Schilling said. It’s an ingenious device, but it can be difficult to use, even for other scientists. It’s also expensive – creating a new one could cost up to $30,000, depending on the components. Several research teams in the United States and abroad, including the interdisciplinary team at SEAS and IPCH, are working to bring the cost down to around $6,000.

Our goal is to figure out how to make this technology accessible and transferable at a lower price,” Schilling said. “We want to simplify the instrument design and software so that our partners and collaborators around the world can have access to the same powerful method.”

The more widely the microfading technique is used, the more useful it becomes.

If we can make the device and method more accessible, then the global heritage community will begin to build larger predictive datasets,” Gilchrest said.

Ella Wang, a high school student from Arizona, who has worked with MFT through MIT’s Research Science Institute program, which recruits top high school students from around the world for immersive science and engineering research during the summer, said added to search. Together with Schilling and SEAS Associate Dean Vincent Wilczynski, she used color maps and fading simulations to model the fading effects of UV rays.

When the researchers finish collecting data for the Afghan Rug Project, they will provide their research to the NGO, which will use it to help rug weavers obtain the best quality materials for their crafts. “It’s a small project with potentially big impact,” Gilchrest said. As well as getting valuable scientific research out of it, she said, it’s a chance to make a difference for a particular community at a time when it needs help the most.

There is an urgent need to help these threatened and underfunded communities to document and preserve their heritage,” she said. “And with our deep, built-in scientific and artistic capacity at Yale, embodied in IPCH, it behooves us to continually ask ourselves what more we can do on the world stage.”

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