“Our job is to fight against entropy”: Narayan Khandekar on the Straus Center and the Forbes Pigment Collection


On what he does:

Narayan Khandekar: My name is Narayan Khandekar. I’m the director of the Straus Center for Conservation and Technical Studies. I'm also the head of the analytical lab in the Straus Center.

On the history of the Straus Center:

NK: The building was created in 1927 by Edward Forbes. He was the second director of the art museum. What he wanted to do is create a laboratory for art. He was very interested in professionalizing the practice of museology in the US. This was his way of using art as a training ground for future directors, curators, registrars, and conservators. So that was the purpose of the original building. The building you see now has the original courtyard from that building, and it also has the brick facade, but the rest of it is a reconstruction of the Renzo Piano workshop. That updated all the facilities. It gave us state of the art lighting, air conditioning, HVAC, and opportunities to borrow and exhibit works from other major collections which we were limited by because of the facilities. It also gave us an amazing conservation studio as well.

On science’s role in technical art history:

NK: We want to understand the materials and techniques of artists. It's part of a field called technical art history. To do that, we want to understand the choices that an artist makes along the way, like making a work of art is a series of decisions. We want to understand those decisions. If we can't talk to the artist, then the work of art is the next closest thing that we can we have to conversation with the artist. We will take a tiny sample from a painting, say, or whatever it is that we're examining, and we will then look at the pigments that the artist has chosen, the binding medium, we'll look at the ground layer, we'll look at the support, which could be canvas, or wood, or whatever. We’ll just build all that together. Then, we can look at how that work of art has changed over time. One of the works of art that we looked at a few years ago for an exhibition called “The Philosophy Chamber” was a portrait of a British Prime Minister, William Pitt, given to us by Benjamin Franklin. It was the first sculpture in the Harvard Art Museum's collection. We wanted to understand what it might have looked like originally when Benjamin Franklin gave it to us. We did a lot of research into the materials that made up the sculpture, which was coade stone, this specialized material used for casting, and then we looked at the layers of paint. What we wanted to do is get back to the original surface, and by knowing the layer structure and the materials that were used to paint it, we're able to unpack that repainting and get back to the original surface.

On the applications of their research

Noelle Chung: What are the direct applications of what you learn?

NK: It helps us understand the artistic process. That’s an important part of it. It also allows us to look after the work of art too. For example, we have some amazing Rothko paintings, some very big murals, and we wanted to understand what they were made of because they'd faded very badly. We did some studies of the pigments, and we found out that there was a pigment called Lithol Red. There are various versions of Lithol Red. We found out that one of them was very light sensitive, and that was used a lot. It made these huge paintings, maybe a nine feet tall and 20 feet wide work, and very light sensitive. That told us that we needed to store them in the dark and to be very careful about how much we display them. That was important. We were able to take that knowledge and apply it to other Rothko paintings that we have in our collection, look at those, analyze the pigments and then determine how much we can display them or not. That came into play just recently with a Rothko painting which has a Lithol Red background with a black and a white field on it. What we're able to do is say, “it can go on display for this amount of time, and then it needs to go back into storage.” What we're doing is protecting the painting from light so that it can be preserved for as long as possible. It also helps us understand how much we can lend out the painting. We will make the decision about whether it's possible to lend it based on this kind of understanding of the materials that it's made of.

NC: So, it's important towards maintaining the health of these pieces of art.

NK: Exactly. We know that nothing lasts forever. Our job is to fight against entropy. We’re trying to slow down that process. We want these works of art to last as long as possible. We also know that they're not going to last forever, but we want people to have them. We want students at Harvard to be able to come and appreciate this incredible treasure. I I'm getting off track a little bit here, but this is one of the major collections in the country. We have over 250,000 works of art in this collection, which makes it one of the biggest collections. Size wise, it's about the same size as the Museum of Modern Art. It's a little bit bigger than the Philadelphia Museum of Art, a little bit smaller than the Art Institute of Chicago. So that gives you a sense of where it slots in on a national level. For the Harvard students to have this on campus is an incredible resource. What we want is for the students to be able to have access to these works of art for as long as possible. The university has been around for a long time. We’ve got no reason to think it's going anywhere.

NC: I never realized the scale of this place. I'm also curious about who relies on the Straus Center’s work and collections. Is it just the workers and students? Or people from across the country?

NK: The work that we do has an impact on a national and international level. We publish an awful lot. This department puts out publications on a regular basis. We go to conferences, we talk, we share all that with professionals, but we also teach a lot. We have students who come into the department, and we run classes. We do a lot of teaching that way. The focus of our department is really on the museum itself. We are focused on understanding that the objects in the collection, and if you understand the size of the collection, you can see that it's a full-time job and we have over 20 people in the department and that keeps us more than busy.

On the Forbes Pigment Collection:

NK: The Forbes Pigment Collection is named after Edward Forbes, who started the collection. He was the second director of the museum. He was here from between 1909 in 1944 as the director and a little bit before then as a curator. What he did was develop this field called technical art history, which is understanding what a work of art is made of and understanding the changes that happen over time. He was really looking at the materiality of a work of art. To do that, he employed the first scientist in a US museum, but more importantly, the first scientists to focus on working at fine art. What they did was look at works of art, identify the pigments, identify the binding media, identify all the materials that make up a work of art. When you're looking at an unknown, which is the work of art, scientifically speaking, you need a known standard for a comparison. So, the pigments that we have in our collection are our collection of known standards. The results from that analysis, for example, in infrared spectroscopy have been shared through an infrared database. Every museum in the world has access to that infrared database and can use the results that are collected from the Forbes Pigment collection. That is one part of the work we do. It's also very helpful to understand when you're teaching, to show people what a work of art is made of and where those pigments come from. We’re used to going to a store and just buying the stuff off the shelf. But if you think that umber, for example, or any other earth pigment, any ochre actually can come from a lump of dirt. All of that comes out of the ground and then is ground up, refined, and turned into a pigment. It changes your understanding of that or the lengths that people will go to make a pigment like Cochineal which is an ancient pigment that comes from a beetle that grows on a cactus. You have to cultivate the beetles on this cactus, scrape them off, harvest them, and then extract the red dye. It’s an awful lot of work for people to do that. It’s a dye that was so valued that it was, I think, the second highest source of income for the Spanish Empire. It was a very, very important commodity for Spain because this is a dye that came from the Americas.

On the components of paint:

NK: A pigment is a small particle of colored material. It is mixed in paint in the simplest forms with something that holds it in place, which is the binding medium. So, you need two components, you need the pigment that gives the paint the color and then the binding medium that gives the paint its handling characteristics. That’s its brush ability, drying, whether it bulks up, whether it's matte, whether it's glossy, that kind of thing. The pigments in a binding media react differently as well. The color that you get from the pigment in the binding medium depends on the chemistry and the refractive index of the binding media. These two things are they have an important interplay together, and they are used in different ways, but that's essentially what the simplest paint is. Pigments can come from animals, minerals and vegetables. You’ve got famously Indian Yellow that comes from the dried urine of cows fed mango leaves, you've got Tyrian Purple that comes from the murex mollusk. You've got Cochineal that comes from beetles or Kermes, which is the etymological origin of crimson, Harvard's color. You’ve got this animal source of pigments, and you've got minerals which had dug out of the ground. You’ve got ochres, you've got umbers. There are lots and lots of these kinds. Vegetables as well. You've got other pigments that come from plants, like weld, which is a yellow dye. It goes on and on. There's no end of examples. More recently, pigments are made in labs. Scientists are developing more pigments, mostly organic pigments, these large conjugated organic systems. They absorb sunlight according to how the electrons move around that molecule and reflect other light. The business of pigment development is still very, very active.

NC: How about the binding mediums? What are they made of?

NK: They're made of all kinds of things. I'm so glad you asked about it because they get overlooked. They're not exciting to look at, but they're so important in paint. They're so important that when you look at the world text on a painting, it describes the binding medium. It'll say, “oil on canvas,” or it'll say, “tempera,” which is an egg, on panel. The binding medium is really important in what a painting looks like. It can be a lot of different kinds of oils, but you want it to be a drying oil. It must be a drying oil. It needs a conjugated system that allows cross linking between the oil fatty acids. That creates a hard and resilient layer. You can have egg tempera. You have a proteinaceous binding medium where the globular proteins denature. They sort of invert, and it becomes a hard insoluble paint layer. There are other proteinaceous binding media like collagen. It can come from animal hooves. Essentially, it's jello -- it's the same kind of material. That will dry and you see people like Mantegna using it. It has this dry, dusty kind of appearance on it. Milk protein is another protein. You’re taking the casein out of milk and using that as a binding medium. You can have carbohydrates as a binding medium. You have in watercolors, for example, the gum that comes from an acacia. It's gum arabic, and it is a binding medium that's water soluble, but it serves to hold the pigment in place as well. It has a whole different set of handling characteristics. So binding media come from all different places, the most modern binding media, so there's a development in the 20th century. You’ve got nitro cellulose, which was used on car lacquers a lot of household furniture, and that was used but it's also quite unstable and unsafe. It's a fire hazard. You've got things like alkyd paint, which is often described as an enamel or baked enamel. You find that also on cars but it's something that is an adaptation of an oil idea using slightly different chemistry. You can have things like acrylic binding media. So, there can be acrylics, it can be all these kinds of materials that are actually very stable, and don't need solvents to handle them. They’re actually quite favored by artists, and they dry in an entirely different way. They are not drying by crosslinking, but they're drying through creating an emulsion or a group of micelles. As the water evaporates, those micelles coalesce, and then the paint forms that way. You end up with a different paint, but it feels a lot like oil paint, slightly different handling properties. Some people like it, some people don't. But it is very, very common now. It goes by a lot of different names, it could be called latex, or the stuff that you buy at the hardware store is an emotion paint, it's an acrylic emotion. You all the time. Anytime it's water soluble, that's probably what you're looking at.

NC: Oh, wow. I'm sure a lot of us have heard of tempera paint, but I had no idea that so many binding media are organic.

NK: Oh, yeah. There’s even more, we can talk about encaustic, which is wax. That was used by Egyptians to make funerary masks. It was used by people like Jasper Johns in the 20th century. These binding media, you think about them being ancient, but they're also used by modern and contemporary artists as well. These things span time and get used and reused.

On describing some binding media in the collection:

NK: We have here a binding media collection. You can see there's a lot of different resins here. These are saps that come out of trees. You can see that they're slightly different colors. They have different handling properties. The chemistry is sometimes similar, sometimes different. That’s part of the collection that I've divided them up into. They're sort of chemical groups. Let's see, what do we got? We've got the polymers here. We've got some of the very earliest polymers that we used on art. This is the first sample received 1929 of vinylite, which is polyvinyl acetate. This Aquadhere that I added myself, it is a polyvinyl acetate. It comes specifically from Australia. It's used by a lot of Australian Aboriginal artists as a binding medium. It's used because it's known to be stable. We have materials like that that are in the collection. We've got things like amber varnish, which is terrific. This is chunks of amber that we know mostly from jewelry, but you can dissolve that and turn it into a varnish itself. Some people use it as a binding medium as well. They like this golden glow in the paint.

NC: Wow, that's beautiful. You know, a lot of these media are solid. Do people dissolve them?

NK: Yeah, it needs to be dissolved, it's mixed and ground. Oh, this is nice. I like this. This is honey, which is sometimes used as an agent for keeping flexibility in paint. This is a sample of honey from the 1940s I believe. Honey has a slightly anti-microbial property. You can see there's nothing growing on it. I'm sure you could eat it if you wanted to. I'm very happy to have that. Here, we've got what I was talking about earlier, the rabbit skin glue, which is collagen from rabbit skins. This gets dissolved in water. It can be either used as a glue, but it can also be used as a binding medium. There's a crossover between glues and binding media, as well.

NC: What’s done to oil-based media?

NK: Let’s have a look. Up here, we've got some oils. There's oil, which is still liquid. So, if you want to use them, you can use the oil, but you also need to use a solvent. You can use turpentine or some other organic solvent to solubilize it. It allows you to brush it out. There are different ways of preparing the oil to you can. You can accelerate the aging process and make it thicker. There are different ways of doing that. One is to add chemical accelerants in there, or you can leave it in the sunshine. Or you can leave it exposed to the air for drying. That allows the oil painter to have different handling properties.

On select pigments from the collection:

NK: Here we've got examples of different pigment. We have raw materials on the bottom shelf. We've got a whole group of ultramarines, we've got groups of cobalt, violets, and so on. This is from an exhibition in 1942, where there’s one of each kind of pigment. Ah, so this is this is the murex that I had mentioned before. This is something that was so incredibly valuable that it was reserved for imperial garments. Roman senators used it on the togas. It's a very, very valuable pigment. It took to get a gram of pigment, something like 10,000 mollusks. It’s a very, very time-consuming process. We’ve been in touch with a guy in Tunisia who still manufactures that according to the ancient recipes, and we have some samples of those as well. There are things like sepia, which I don't know if you'd know comes from a cuttlefish. It's used as an ink. Graphite, which we all use in our pencils, can come as an ore. Here is naturally occurring graphite. We’re so used to it being a synthetic material that we never think about being actually available as a chunk of something. This is something that was great. I went to the launch of Crayola’s new color blue crayon. A few years ago, they launched it. It was based on a pigment called YInMn blue. It’s a very deep blue, and Crayola based the new blue pigment on that. This was available at the time. I nabbed it and brought it back to the collection. You know, this is lapis lazuli comes from Afghanistan. It comes from the North-East corner of the country in the hills up there. It’s very, very difficult to get to the mines. The ore is dug out, it's carried by people, and then it's carried by donkeys down to Kabul, and then down to the coast and then taken over to Europe. The name Ultra Marine, which is what the pigment is called, means “from beyond the sea.” It describes the location where the pigment comes from. These kinds of little insights into pigments origins are often buried in the name. This is an Egyptian blue, which is another this is a very, very old pigment from Egypt. It was a synthetic pigment using copper and silica. Its process was lost for a long time then it was rediscovered. So again, you know, we rediscover technologies that were lost. Another good example of that is Lead Tin yellow, which is this pigment, so it was used a lot on European paintings up until about 1750 and then it dropped out of use or disappeared. It wasn't until 1940 when it was rediscovered.

On other objects the collection houses:

NK: Here are groups of things that that belong together. We've got new there's a painting in the MoMA called “Dive Bomber and Tank” made by Orozco’s assistant Louis Rubenstein, who was a Harvard graduate. He gave us the pigments that he used on their painting. This is a paint box that belonged to John Singer Sargent.

NC: No way.

NK: Yeah. If we look in the bottom here, it says “this belonged to John Singer Sargent.”

On the Straus Center’s Lab Equipment:

NK: We do a lot of work with individual sort of components that make up a work of art. If we want to look at the layer structure of a painting, we will hop across section. This here is from one of the gallery walls. You can see how every exhibition has its own paint color. You can see an archeological sort of history of the painting.

NC: So like physical, actual layers.

NK: Oh, yeah, absolutely. In polarizing light microscopy, we can look at a pigment dispersion. Here, you’ve got a tiny little sample of pigment that smeared in there. Then you can put it under the microscope, and you see the individual pigment particles, and then you can identify them. Here is a Raman spectrometer. I think the run has finished. What we can do is collect a Raman spectrum and id a pigment. We have this large stage, so we can put a flat work of art under there. It's great for watercolors, we've been doing a lot of work with Indian and Islamic manuscripts. Fantastic for collecting data about that. When we're collecting this kind of data, we need a set of standards. So that's what this collection of pigments provides for us. Then got infrared spectrometer. What we do is put a tiny sample of material under here, we put it into a diamond sandwich. It's sort of gets squashed between two diamonds, and then the light passes through. Then, we can collect a spectrum. We can compare it to our library of standards and identify the pigment or the binding medium that way.

On his final message:

NK: The work of the museum's is something that's right there on campus and available. It's an incredible resource. It's a world class museum. It was the center in the first part of the 20th century for how museums operate. That legacy still exists. If you want to understand how museums work and what they're doing, come visit the museum, but take time to appreciate the art because it's really one of the best collections in the country.

Noelle Chung, ‘25, is a reporter for WHRB News. Follow her on Twitter @Noelle_Chung_ . For any questions and news tips, please email news@whrb.org. Tune into "As We Know It" on Sunday at 12:00 p.m. ET for more stories like this one.