 Welcome to the Heritage Science Research and Testing Lab at the National Archives and Records Administration. I'm Dr. Lindsay Oakley, one of four scientists here in the lab who work with many different types of equipment and technology to understand the collection, the materials they are made from, and how to preserve them. We are excited to give you a tour today and show you what our lab work looks like and how it helps ensure that future generations will continue to have access to important archival records and information. Our nation's most recognizable founding documents, such as the Declaration of Independence, the Constitution, and Bill of Rights are held here at the National Archives. A team of experts in conservation, exhibit design, and heritage science work together to make sure that these documents are safely displayed over the years for visitors. Let's turn here to meet one of the scientists who works with especially designed encasements made to preserve these precious documents. This is Mark Ormsby, physicist, one of the scientists here who works with these specialized encasements. And, Mark, it seems like there's a lot going on here. Can you describe for us what we're looking at? Sure. So the archives had an exhibit a while back called What's Behind These Words? Meaning, what's the story behind the Declaration, the Constitution, and the Bill of Rights? And part of that story is in the billions of records at NARA houses. But what's literally behind the charters is a lot of wiring, a lot of plumbing, a lot of sensors. And you can see that here. This is a Spear encasement, like the ones we have downtown in the Rotunda. And these encasements were built by the National Institute of Standards and Technology, and the documents were sealed about 20 years ago. So you have the parchment document, the glass, a special frame, and a seal here. And the interior, we removed the air and replaced it with humidified argon. So there's no oxygen inside, so that helps to prevent reactions that depend on oxygen. So the goal is for this seal to maintain an atmosphere without oxygen for 100 years. And that's a challenging goal. And so part of our job is to monitor how well the encasements are doing. So we have a lot of equipment here, different sensors. A lot of what you're seeing here is equipment for measuring the oxygen concentration. So we have an oxygen sensor here connected to a lot of valves. There are temperature, humidity, pressure sensors inside. And normally when we want to take measurements, we have to do that overnight because the charters on display every day. So that limits what we can do. But during the pandemic, because the Rotunda was closed, we were able to get in there and take measurements over many days. So we have some better data to work with. So that's what a lot of this equipment here is for. And this is all part of the effort in preserving the documents, leading up to the 250th anniversary of the Declaration of Independence in 2026. So Mark, obviously not every document at NARA is in a specializing encasement like this. How are other records preserved? Right. So the archives has billions of papers, maps, photographs, motion pictures. And we can't have a custom design temperature and humidity sensors for everything. So in our storage areas, we use data loggers to record the temperature and humidity because the most cost effective way to preserve the records is to provide good storage conditions, which generally means cooler and drier conditions. And so we use the data from these loggers and we work with conservators, archivists, our engineering staff to monitor the conditions and make sure that we're meeting our specifications for providing a good environment. I also see behind you some historic papers. Can you tell us a little bit about that? Sure. So besides looking at the big picture and, you know, huge enormous storage areas, we do look at individual items and collections of items. And so this is paper that is about 500 years old. And you can compare that to one from the late 1800s. And you can see that this one that's about 500 years old is really well preserved. And this is part of a study collection that was collected by Tim Barrett, who's a paper maker. He's retired from the University of Iowa now. And he's a former Fulbright fellow who studied paper making under a Fulbright fellowship. And I started working with Tim because he was interested in the role that gelatin sizing might play in helping to preserve these papers. So gelatin was a coating that was put on them. It's not easy to measure how much gelatin is on there. You can do it destructively, which we did on these study samples, but of course we don't want to do that on our collections. We tried measuring it with ultraviolet light, with mid infrared light, using other equipment in the lab. But those microscopes weren't sensitive enough. So we got this near infrared system and developed a chemometric model. So near infrared light has a number of advantages as far as collecting data in the near infrared and looking at the gelatin. But it's more complicated to work with mathematically. It's more difficult to interpret. And we could do this all non-destructively. So we collect the spectra and we developed a model using calibration specimens, went through a lot of processing to develop the model, examined about 1,500 European handmade papers. And we looked at a lot of properties and what we were able to show was that over time the gelatin concentration decreased significantly. And this is a trend that held up across countries, across a variety of ways of looking at the data. And so we had all this data, 1,500 specimens, a lot of techniques for looking at it. And the real key in understanding how all of it fits together was a materials and workmanship rating, which is the data plotted here. And that took advantage of Tim's expertise as a hand paper maker. Again, we were able to show these trends, depending the trend and quality or the amount of gelatin held up when we looked over the craftsmanship ratings. And that's what really allowed us to combine this information. And it was a really good example of a collaboration where we're doing a lot of really technical work, a lot of mathematical work, a lot of data analysis, and a lot of discussion back and forth with an expert in the field, trying to understand how the pieces fit together, what it tells us about the tradition of hand paper making and how the technology and the economic aspects of paper making changed over several centuries. And at the same time, we also learned some things about some properties that might affect how more modern papers, how they age over time. Let's keep going on our tour and meet another scientist at work. Here we are on the X-ray for lessons lab with Dr. Jennifer Herman. What are you working on today? Today we're analyzing a Fractor that you can see here. It's a family history record. It records the births, the deaths, the marriages. It was very precious to people in the 1800s but in the early 19th century in order to get pension benefits for deceased service members, the family had to send it to the government. It was probably very hard to part with it. However, they are now part of our holdings and so they're preserved for future generations. A lot of them were laminated in an early plastic called cellulose acetate and even though a lot of research was done on cellulose acetate as a preservation technique because it helped keep the Fractors and other precious documents like the Louisiana Purchase from tearing or getting dirty, through natural aging we found that when it degrades it can sometimes release acetic acid, also known as vinegar. So we are doing this analysis in order to make sure that we can safely remove the cellulose acetate lamination but in order to do that we need to soak it in acetone. The conservators soak it in acetone. So I've already analyzed the yellow and the red pigment and we know that they're inorganic and I'll show you that on the computer in a second. But we need to make sure that the blue is also inorganic so that we know that it will be safe to delaminate this in acetone. If the pigments are organic, then they could dissolve or fade when put in the acetone and we obviously don't want to change the document negatively. So everything looks good here. So here I have the spectrum for the red pigment that I showed you over there and the yellow pigment and we can see a large signal for mercury. The mercury tells me that this is vermilion which was a very common pigment used in this period. The yellow peak seen here shows lead and chromium and that tells me that the yellow is also an inorganic pigment which is yellow lead chromate. So both of these pigments will be safe for the delamination. Now we're going to run the blue that I had just finished setting up over there. So I'm checking it. It's in the right position starting the x-ray. So this will just take a couple of minutes. But we can already see a signal for iron appearing and we think that this is the iron-based pigment Prussian blue. Prussian blue is really interesting though because it has an organic component as well as the inorganic component. But this instrument which is an x-ray fluorescence instrument only can see this section of the periodic table while the organics are not seen, cannot be detected by the interactions with the x-rays because they're too light. So the instrument's done running and we can go over to the FTIR now though and see if we can detect the organic portion of it to fully confirm that the document will be safe for delamination. And I should mention we dimmed the lights while running it so that the document was not experiencing any more light than it was necessary. So this is our FTIR and it's great that we have this complementary technique to the XRF we were just using on the laminated fractors because this instrument detects the organic portion of the sample. So we have an orphan flake from the fractors and this one was not laminated so we can use it in this instrument to look at the organic portion. The infrared light will interact with the compounds here and we will see peaks that are characteristic of stretches and vibrations in our analytical spectrum. And the instrument is thinking and oh here we can see quite clearly the cyanide peak from the Prussian blue. And so now from the XRF we were able to see the iron and combined with this organic section of the cyanide molecule we know that this is definitely Prussian blue and so therefore from all the analysis we've done we know that these are inorganic pigments. So Jen how does having analytical information like this help preserve records at NARA? It means that we can make science-based decisions and instead of having to just hope that the pigments used are inorganic and won't dissolve in the delamination treatment we know that they are inorganic and therefore will remain unchanged during this treatment and so the conservation treatment will further preserve the records safely based upon our scientific analysis. Thanks Jen. So here we are on the last stop of our tour with Dr. Henry Duan. Henry what are you working on today? This piece of equipment is called micro-fading capacitor. What it does is to focus intense lightening on a tiny spot on the record which you can see here but you can see this magnified image to detect its color fading in a short period of a few minutes. So how is that data then used by other experts at NARA? Okay so based on the fading rate on this light on that spot we compare it under the same condition with this piece of reference spot which contains a different color dye with a long fading rate and you can see this is the fading curve on this blue dye after it falls it fades here you can see the blue fading here and by comparing this fading data with this one we can assess roughly how that image will fade in actual display lightening condition. This data will help us make a data-driven decision-making to mitigate the display risk in terms of lightening design and exposure period. Thank you Henry a fascinating place to end our tour. You're welcome. The types of records NARA holds are varied and we are dedicated to both preserving them and providing access for the public in future generations. Scientists who work in the Heritage Science Lab are flexible and work with many different types of techniques and instruments in order to answer the wide range of questions that our archival records inspire. Each time we analyze a record we provide another layer of information to the history of these records and a deeper understanding of the complexities of preserving the records and the materials in NARA's holdings whether they will be displayed, handled in research rooms or stored safely for future use. Thank you very much for visiting the lab.