Okay everyone we're going to give it just a few minutes to get this webinar started. We're going to let the room populate as we always do at the top of the program. And I'm going to go ahead and share my screen. Okay well, welcome everyone to today's webinar a discussion of cold storage theory and practice for photographic and paper based records this is another program of C to C care. I'm going to go through just a couple of super quick introductory slides and then we're going to go ahead and jump in today's program. My name is Robin Bauer Kilgoe I am the C to C care coordinator. You can reach me by that email address on the screen to see to CC at cultural heritage.org. Very quickly that is our home on the web connecting to collections.org from there you will be able to find all sorts of fun resources, including our back archive of programs curated resources links to our community and all sorts of fun stuff so if you haven't had a chance, please go to that website. We also have two homes on social media Facebook and Twitter, both under C to C care so we encourage you to go join us there if you're able to. We have a couple of quick technical notes on today's program we have enabled the chat box and we also have a Q&A box the chat box is there for you to say hello. Maybe say where you're located I'm located just out of Washington DC and Silver Spring, Maryland. You can also put general comments in the chat box, our Q&A box is there for questions for our presenter so at any point during the program, you can put a question for us and we'll try to get to at the end of it. Also we've enabled closed captioning for this program so if you want to enable that you just need to hit the CC button or the three dots at the bottom and you will be able to access that. We've also are going to be recording this program and we've already posted the presentation and some resource links on our website. So I will put the link for that in the chat shortly so you can access that if you'd like to. And just a quick programming note we have our webinar for March already scheduled if you want to find out more about exhibiting photographs you can sign up for that free webinar we do do one free webinar month. So go to our website, click on the banner for exhibiting photographs and you can register for that webinar at any point. I'm going to go ahead and stop sharing my screen now and introduce our presenter today his name is Mark McCormick Goodheart he's director of Ardenberg Imaging and Archives. He is the founding director of that group and Mark has 30 years of professional experiencing an imaging imaging and material science. We're excited for today's program because as he'll tell you we're going to do a bit of a show and tell along with the presentation so it should be a good time. So Mark feel free to take over whenever you're ready and I'll be here to answer any technical questions via the chat and see you at the end during the Q&A period. So Mark go ahead whenever you're ready. Okay. I must say thank you Robin, I haven't done a zoom presentation with quite this level of technology so it just seems like a lot of things could go wrong but and also the slide presentation is running a bit long so I'm going to you might see me put a few bullet points in it and so forth. But I wanted to do a show and tell that I was originally thinking of putting at the end, and I've decided, we're just going to move it forward so that I don't, so that we get that in, even if I have to cut the slide presentation a little short but you do have it available to you the whole thing on in the resource materials. So let's get started I'm going to use you in this presentation I'm going to be talking about. I'm going to use a couple of terms. One is chromogenic color materials and if you don't know what that is. I don't want to give you a long technical explanation I think it's better you'll know it when you see it so I'm going to show you a couple of examples. And I've got a second camera set up so I'm going to have to come up closer to it to show you some close up materials. Here we go. If you remember the one hour photo finishing era. You're, you'll probably remember packages of one hour photo finish materials, you would get. Certainly in the 80s and 90s double double prints were were very popular. They are chromogenic color materials, they're things like active color print material food color crystal food color crystal archive. The consumer would get back things that look like this. Let's see if I can get there. And you can see that these crazy looking orange negatives, the orange was a was a color reproduction. It was a color mask that helped with a color reproduction. But when you add the fact that these are reversed, and then you add the fact that they're kind of orange looking. A lot of consumers just threw them out and which is unfortunate. But that's what I'm talking about by color chromogenic. And the second thing you'll hear is acetate base that negative I just held up is on a tri acetate base. So the, so I just want to give you those that heads up. So what I wanted to engage you with is the fact that with cold storage, we really want to monitor cold storage and we want humidity monitoring devices to do it. It was a lot harder 30 years ago, but the technologies come a long way. So, what we're really trying to do is we're trying to monitor moisture content in a sealed system because you're always going to be putting photographic materials or any records based collection they're going to always be in a document box, a container. These are these established micro climates and because of that. We're dealing with moisture content and sealed systems a lot. And so the first show and tell I wanted to give you some idea is. I'm just about to put this book into cold storage. I came off a shelf in one of the rooms in the hide house and I actually don't know what the moisture content and I would, in other words, I don't, I don't know what the equilibrium humidity in this sealed package is. So the very simple way to, to check it, which is simply put a data logger in, and you're going to seal it in a, this becomes a sealed micro climate. And you're going to leave it, say a couple of hours, and I've kind of already done that so I think it's really close to the proper reading but you're going to let the hygrometer. Establish an equilibrium RH and the book is going to establish an equilibrium RH, due to the moisture content in the book. And it's going to give you a reading in this case, I actually, it actually was coming in at 50% RH, which is actually perfectly this, this, this book is an equilibrium moisture content where we can go right into cold balls and I don't even have to worry about doing any other kind of conditioning, and I wouldn't even recommend conditioning unless you're, you've got something that's extremely damp or extremely dry. And we'll talk about that in the slideshow where, where those tolerances are. So the second thing I wanted to show you kind of a show and tell is that if you use the same technique, and if you put a hygrometer into a package to test say is the matboard too dry. Is it dry, what's the condition. But in this case this is not a very dry matboard it's the hygrometer the mechanical hygrometer to see it is is reading about 50% humidity again very similar to the book. And the, you can see that the humidity indicator is also. If I read where I get lavender it's kind of between 40 and 50% it's actually kind of let it's really kind of between the two so it's sort of saying 45%. So there's a basic agreement there. And I'm going to add one more in the package, and that would be we're going to use a data logger. There are Bluetooth data loggers like this one, and that's a blue maestro it's less than $50 and it's really quite accurate. So I would often put that in. I'm just going to put that in the package. Here's a very inexpensive it's literally you're buying the batteries is like a $3 one. It's, you can't calibrate it but you can certainly check it against a more accurate device, and then you can kind of just use, you know, Kentucky winters you know it's reading a little lower it's reading a little high. But here's the thing. And this is this is what I want to show you all of these devices. One is electronic, and this one, and I'm sorry, this one's mechanical. That one's electronic, this one's electronic, and the humidity indicator card is also a chemical and what's going on there. So what I want to establish so that you can understand where I'm going with the slide presentation is that an electronic hygrometer if I take that package and I put it in a set of cold vault like a freezer, even a reach in and I let it establish a new equilibrium, what you're going to see is that the mechanical hygrometer and the moisture indicator, don't read the same as the electronic hygrometers, and the reason for that is the electronic hygrometers can be temperature compensated. So they can give you a temperature compensated estimate of the relative humidity in the package. So you let everything come to equilibrium and what you're going to observe is that the electronic, the electronic hygrometers are going to read much lower than what they were reading at room temperature. So, for example, this 50% package, if I now put it in a freezer, let it go overnight and or maybe in a couple days and come back and look at it it's now in an at rest equilibrium condition at say 20 degrees minus 20 degrees C, you're going to see that it reads about 35%. So you're going to see that the moisture indicator card and the mechanical hygrometer are staying essentially where they were. So why is that and that's what I won't that's really the observation I want you to observe for yourself if you ever do this kind of work but the mechanical hygrometer and the chemical hygrometer are responding to moisture content. So, because this is a sealed system and a sealed package, think of a sealed container or a sealed ziploc bag. Since the moisture content has not changed in the package, you've gone into the freezer, you've cooled it down, but the moisture contents the same. The two mechanical ones are the chemical one and the mechanical one, they're going to read the same moisture content therefore they're giving they're going to give you the reading they were giving you at room temperature. That's a good and a bad thing the good thing is what it's telling you is that yes this is in a freezer, and it's, but when it comes out of the freezer and it goes back to room temperature, that's going to be the humidity you should expect. The one the electronic hydrometers you have to do a little mental math you have to say well they're reading 35%. But let's add 15% to them when they come out that package is going to come out and it's going to be back to where it was 50%. So that's really the that's really the show and tell lesson that I wanted to kind of get everybody on the same page on is that depending on whether you're working with electronic hydrometers that are temperature or you're working with mechanical hydrometers. You're, you're going to either have to commentate them when you think of the mental math of when they come out of the cold ball, or if, or if you're using a mechanical hydrometer or indicator card, you're going to say they're telling me what it will be when it comes out of the cold ball. Anyway, that's an important distinction and I just want to make sure that everybody was on the same page. So that's why I decided to start first with show and tell. So I think it's, let's, let's get into the let's get into the share screen mode. All right, hope everybody can see that all right. We'll start the slideshow again runs long so I'm going to kind of skip through it a little bit, but we'll hit the high points hopefully. So I just described acetate base it's plastic support, very, very common all through the 20th century and even to today for people that are still shooting film, the small amount of us to do. There are significant problems and there are a lot obviously there's a lot of degradation mechanisms that can have in the photographs, but acetate based deterioration and light and heat induced fading and staining of color chromogenic film and print materials are really two big important ones that cold storage. It solves that problem to a largest extent because it really slows down those rates of decay. And when you're looking at the 20th century, clearly from them, certainly from the 1950s on. There are other materials like nitrate film and also benefit paper based records like my grandmother's book that I showed you they benefit. Of course that is more stable to begin with. So you can argue, maybe it doesn't need to be as cold storage, as much as of film materials but, nevertheless, cold storage slows all of that down and that's why we're really doing it. On the left is acetate based deterioration and I show you this I think I got this while I was at the Smithsonian this this image and I, I have to say I really love the creative, great creativity of someone who actually took the time to do a rubber stamp saying he destroyed because it seemed pretty self evidence to me. On the right is is a coat of color transparency. Now that's not all that common. Most people go from coat of color negatives to coat of color prints. My father was an early adopter, and he and the process would allow you to make slides from the negative so you could think both slides and prints and he did that. And interestingly enough, because the slides got into slide magazines and carousels, whereas the negatives just kicked around in a shoebox. I really don't have a lot of his early negatives, but I have these coat of color slides. What I want to show here is simply that one of the common mechanisms for thermal fading is that they tend to shift red over time and you can see that here. This, by the time this got into my cold storage it was already 35 years old and it's already sort of shifted red, but of course today it's easily color-restorable. Again, here's the process. I think we've, I think we've kind of talked this through so I'm not going to spend a lot of time on the slide. I, when my wife would use pork at studios I would always ask them will you sell me the negatives and some wouldn't some wouldn't. And so I've, and I actually have learned, I guess I've come to the sense over the years that I actually do want to collect some of the ephemera to put the things like the, the envelopes that they came in and the, and all of the sort of packaging I tend to put that into cold storage as well because I think it's kind of, I think it's interesting from a historical perspective. The other thing I want to tell you about this slide is simply that those prints that went, I, we would often do double, again double prints even when we had enlargement made. So one would go on the wall on display and another would go into cold storage. My cold storage got started in 1993, actually 1991 but by 1993 I had moved to an auto defrost freezer that things that has been running for 30 years now and it's still running. So, but what you can see is that in that 30 year period of time I'm already reaping the benefits of cold storage because I'm seeing that the prints that were stored still have pristine whites, no fading the ones that are on display. It's not terrible but I, they have sort of the patina of age the whites are now a little yellow. The color doesn't have quite the vividness. Many people wouldn't even notice but but they have definitely faded somewhat and discolored somewhat. So, what are the considerations. Well, there's really, there's really three. One is the chemical stability. What are you gaining by doing cold storage and that the reaction kinetics says colder and drier slows aging rates. So the colder and drier the better, but the reality is there are physical safety limits and. And so we had to do a lot of research on what are those allowable tolerance. When are you being too hard on the material by desiccating it or freezing it cooling it and then warming it turns out temperatures really not the issue but but you certainly have to stay in your lane with moisture content. Third would be long term commitment to care and this is actually important but right now I'm pretty sure I'm preaching to the choir on this so I won't spend a lot of time on it but you need to establish a chain of custody education and training because as somebody retires in your organization. You need to know how to, how to interact with the cold ball what kind of what kind of procedures are needed, maybe a staging is required for some of the objects and so forth. Anyway, I'm going to. I'm going to step out now to excel but before I do let me just show you this little table over here. I saw those rates this was published in publication F 40 by George T Eden it's conservation of photographs it was from I think it was published in 1985. And when I was at the Smithsonian in the early 90s and I started looking at this, the first thing that came to my mind was, this is the fountain you. If I can get colds, if I can get photographic materials into sub zero say minus 20, 20 degrees C. I'm looking at rates of 1000 times what a reduction in the reaction connects and, and this table is based on dye stability but the the reaction acetate base follows a very similar reaction rate. So, essentially, if you're looking at dye stability of these materials and you're also looking at acetate base you're getting the same kind of bang for the buck. By putting them into cold storage, but I also, the way my brain works as I said, this is kind of fountain use I mean we've slowed we've slowed the decay down 1000 times if we can get these things in the sub zero temperature. The problem is, is that like the family you, if you're not drinking from the fountain if you go away from it, you're going to return to normal aging rates, and that's what's happening with with cold storage is, we can't really use these materials, obviously. I don't know about you but I don't want to be looking at photographic prints at, you know, below freezing for that matter even at five degrees centigrade just above freezing. You want to return them to a reading room or an area of use.  And I realized that that when you do that, you actually have the factory and the time that it's out of storage. Simply put, if the, if you really like a print and it's always on your desk, and it's not going back in the coal ball within the coal ball that's doing you absolutely no, absolutely no good. So I, at that point I decided to do a time out of storage Excel spreadsheet to help me work through that. So what I need to do is I need to. I'm going to get down here and I'm going to go to that Excel spreadsheet right now. So I developed in the early 90s, a time out of storage Excel spreadsheet. And it's, we will have a work with Robin will make it available. It's not available yet. I do want to make some modifications to bring in physical stability to it it doesn't calculate that at this point but with some conditional formatting I think we can make it do it. Anyway, it's it's a it's an interactive. So you can set the Eastman Kodak by the way, normalized all of their rates to what they considered average consumer room temperature, which they put at 24 degrees C and 40. I believe that it's generating that relative stability of one. So all of these calculated reductions in deterioration, in other words improvements in stability are being based off the idea that if the product is normally aging at room temperature 2440, which by the way if we go up here and we put in 21 sort of a more typical museum environment and we put 50%. But when you make the calculation, it's basically back to one. So that's a, that's sort of a similar type of event. Now let's just say I go down to five degrees C. Sorry, I'm going to go to five degrees C. And then we're going to come over here I'm going to say, at five degrees C we're probably going to be holding 40% of the cold ball. You can see that if the material never leaves the cold ball, it's almost 13 times more stable. By the time you get out 10 days per year over here. It's saying you're really only getting effective rate of 9.8. If you decided that you wanted to keep it out six months out of the year, let's just type in 180, you can see that it quickly. It's down to about a factor of two, because it means half the time it's normally aging and half the time it's doing 13 times better. The integrated result of all that is that you're only getting 1.9. So obviously time out of storage is really important. I'm going to just show you one more and then we'll step out minus 20 degrees C. And we're going to use that remember that electronic thermometer that's going to take 50% at room temperature and it's kind of probably tell you it's about 35 so I'm going to type in 35. You can see that the materials now the predictions are there. They're nearly 500 times you know 460 times more stable. If you're only bringing them out of the vault a few days per year, you're still getting even at five days per year you're still getting something that stick over 60 times more that is that's impressive to me. But if you're always bringing it out, you're only you're back down to not much better than your cool ball your cold ball that five degrees C. And of course the table will calculate that if it's always out 365 guess everything comes back down to normal aging rates because the vault is doing absolutely no good. So that's the way the time out of storage calculation works. I think it's really instructive for collection manage to start thinking really how much time is this going to be out of storage. And I think you'll find that with cold stored collection, particularly negatives. I've actually had 30 years to kind of get an estimate of where I'm at with my collection and the answer is I'm at about two days per year. Out of storage so I'm getting at minus 20 I'm getting 135 times more stability out of the dye for dye stability acetate base again is very, very similar IPI uses the same. So back in the day we you know we would exchange, you know, collegially we talked about our research and and so IPI use the same. In fact, they call the same thing time out of storage. They've, they've got data in their acetate guide for a time out of storage for acetate and the the reactions are very similar so I think it's instructive whether use the acetate guide data or whether use the dice to build data it's going to give you the same understanding. So back to my collection, it got moved from Massachusetts to from Maryland to Massachusetts, and it was out down about a week at room temperature and then there was one other time I had to move it from a garage to a basement so when I add up those times out. Plus, my usage, I come up to about two days per year. So I think it may be that some people think that this should, you know, you want to be out a month out a year but most of the material that go into cold storage are actually very low retrieval rates and they don't have to be out very long. But it's very instructive so we'll make sure that you are we get you this spreadsheet if you want to take a look at it. So back to back to the slide show. I'm going to show you this I'm going to spend a lot of time bullet points, basically two key things are active humidity control in the vault or passive humidity control. And with passive you can do it with sealed cabinets sealed containers sealed packages. And I'm just going to show you some examples. Here's an example of a very large scale high security, actively climate control cold storage which means that this whole entire space is being dehumidified by high volume desiccant dryers. It's very sophisticated to build a vault like this but it is done. And, and, you know, if you got these. These projects often take years to come to fruition, at least in the museum world, Iron Mountain, this is their business so they can get things up and going fast because they've got all the mechanical engineers on staff to do it. I'm just going to skip this is some interesting the way they build this into a limestone mine but we'll move on to try to keep on track of time.  And, but it was set up remote site. It was basically it was set up in a least buildings underground parking area. And then remote site monitors were used to monitor that the vault was working well. Basically, the maintenance was neglected. And the, the, the whole relay from the remote, the remote sensors to the answering service that was supposed to then get a hold of the staff that kind of broke down over the years really bad. It's just really poor maintenance. So, as a result, I was called in to ask them to help them with, like, what do we do, how do we triage this and get this thing fixed. It, I said, basically, you got to replace it's a mess. Okay, let me go back. So what did we see what you see mold and mildew you see rust, you see, these are that's watermarks from water dripping on the, on the shelves and the, they're not cardboard but they're obviously their document boxes made out of paper. And, but the last thing I just want to point out to you that you look right over here and you see this sort of glossy spot on this roll of motion picture film. That's called verityping. The gelatin got so damp that it glued itself to one of the other wraps of the of the film. When you try to unreal this that is going to be a challenge because it's actually kind of glued itself because of the high humidity. I'll talk about that a little bit more. So, when I left the Smithsonian in 98. I talked the management into funding a sort of a different way of doing cold storage. And so we, I worked with Henry Wilhelm Wilhelm imaging research and we, we, we built a just a regular freezer, not actively dehumidified with the dehumidifiers. We were going to passively control the cabinets. These are sealed museum cabinets. They are expensive. And I think for a very small institution, they're still a pretty expensive approach but nevertheless, the project culminated in a success that you can in fact control humidity, when you're in very low temperatures because the absolute amount of moisture in the vault is a lot lower. So, think of a display case that gets buffered with silica gels or arts or well think of doing that in the cabinets at a much colder temperature so you so that the, the amount of charge in the system is a lot less because you're not trying to control it at normal room temperature, you're doing it in very low temperatures. Since that time it's been running since 1999 and it's still running today. There's been a few, you know, a compressor had to get changed out. I talked to Henry recently and they did upgrade some of the auto defrost in it. The auto defrost does keep the humidity down to about 58%, but remember that shift that's going on. If the materials come to equilibrium with 58%, do the mental math, they're going to tack up another 12 or 15%, they're going to get up to 65%, close to 70% when they finally come to equilibrium. Therefore, you are going to use the cabinets and you are going to use some, or you're going to use zip lock bags to isolate the materials and make it that they don't ever get to fully equilibrium with the vault itself. So, Henry and Carol, I don't know all the ins and outs of this, but, but Henry got interested in collecting newspapers. I don't know whether he collects every single day. I doubt it. I think he just picks certain select ones that he thinks are important. I haven't really talked to him about that but he gave me these these slides so I want to thank him for that. This one on the left is the New York Times on September 11, but it has no mention of the Twin Towers falling. It took till September 12th. That's because a hard copy newspaper has to go to press early in the morning. So, the tragedy didn't occur till later in the morning, and the hard copy shows nothing of what was going on. So, I think we're living in very different times where online news is being updated very quickly. But the reason I wanted to show you this is simply that these papers now I would say Henry and Carol have probably the only pristine copy. And hard copy print of the New York Times because I kind of doubt anyone ever took the time to put it into subzero cold storage other than Henry. Very quickly to keep us on track. I'm going to kind of skip this slide. Simple construction and installation. The one thing I want to point out in this slide is simply look at the panels on the floor. This is a regular valley box or Louisville cooler. Any basic refrigeration firm can install these because it's not really sophisticated because it doesn't need the interlocking of the dehumidifiers. But when you're going to do subzero, and you're going to be on like a concrete floor, you're going to get frost-heathing if you don't have an insulated floor. So that's just a point I wanted to mention. But the construction firms that do this, they know this. This is not a surprise to them. This is a poster. You can download it at this link. And it's in the PDF. So I'm not going to dwell on it. We're going to move along, but it will give you a lot more about that project and some of the things that we found during that research. This is my own personal family archive. Again, I started this freezer in 1993. By 96, the metal edge kits, the drop from box design had been worked out. So I slowly over the years converted from more individualized packages. I slowly converted the pack to the whole collection over to the metal edge packages, and you can stand them upright or you can lay them flat. And so basically I'm doing kind of high density packing, still enough to circulate the air in the freezer. And this freezer, believe it or not, holds 46%, which means because it's an auto defrost cycle. So much of my, and I didn't really think it was going to be that low. But in fact, if you, again, if you do the metal mapping, say, well, if all these packages failed and they came to equilibrium with the way this, this reach in freezer is running, they're still going to be safe. So they're never going to go into a too damp a condition. I'm going to skip this slide pretty much other than say there is a shelf life equation that can allow you to predict how long your package is going to last before you have to recondition. And it evolved into a, what I call the drop from box design, and that took me, that was sort of over a period of the year so by 1996. I actually approached metal edge which was a new up and coming archival supplies company at the time and Larry Gates the was very eager to put this into a kit. So we did that I just want to say in the slide, it's not an endorsement of, of, of the manufacturers that have now commercialize the product. I don't get royalties the Smithsonian doesn't get royalties it was taxpayer funded and we, and we're just happy to see people step up and actually start to use it. I also learned recently that Gaylord Gaylord archival has now made a competing competing product, same principles, they just decided to use a humidity indicator, sort of multi pick card. I just want there, I prefer the simple singular design of just one go no go kind of humidity indicator, simply because then I can look in my freezer and I can just see a sea of blue, and wherever I'm seeing lavender, I know to zero in on that package. If you do a scale where you've got pink lavender and blue going on, you're going to have to flow down and look at each package and so I kind of prefer this design to this day but, but I think it's really great that companies have stepped up to help people kind of put this into a kit form and do that design. So here's the first application of the metal edge kit. So, certainly 1970 97. I actually came across the my notes and we did it in 90 late 96 November 96. And this is Shannon parish. This is Karen good. I've got married soon after that's why I really don't know her for her last name now. That's Andrew Rob. He's at the Library of Congress now. Annie was the acting director at the time, and she's moved on to senior positions in the in other parts of the Smithsonian Shannon has now stepped into the head curator role there. And so I called her a couple weeks ago and say hey whatever became of this. They put a number of historically important negatives into cold storage using this packaging design, and the ones that really stick in my mind are the ones that Richard Avedon photograph of Jacqueline Kennedy in her inaugural scale it down. Over here is what I was called the money shot this is the this that's the negative that became the print that went into I believe it was a magazine. And more, this is the. This is a recent freezers at the Norman Rockwell Museum, and a young archivist in 2009 adapted the CMI package design to existing document that they had already done a grant on the four by five negatives were already in that format and so she didn't have to re format and then have to redo finding aids and all that stuff so it made sense to kind of adapt the method to the packages that they already owned. She did that. I just happened on a cold, you know I just was visiting the museum and I just said I'd love to see the archives and like they put the docent at the visitors desk called down. I never gave my name, and I have a hyphenated last name so she instantly recognized that the work she was doing that she have the publications, and, and the, and the guides to how to do it. She recognized my name so she. So I that's how I became aware that this even existed been running since 2009. It's running to this day. It's doing just fine. They did have one freezer breakdown, but again it's like a normal warm up. You just, you just just let it warm up and then, and if it doesn't happen so long you don't even have to recondition and again just put it back into the freezer when the freezer gets fixed. So what is this collection well it's a small collection it's going into to reach and freezers but it's something like. It's a little over, I think it's around 10,000 four by five negatives, and I was fascinated with that so why did Norman Rockwell have so many. Why did you produce so many photographic negatives and prints and the answer is because he would pose local people in very animated pose which you can see, and he would work off the photographs. You can't ask somebody to sit there acting like they're driving a car for an hour while you paint them so basically he used photography as a way of getting that animation and getting the sort of the idea behind the painting and then he would paint a photograph. I did want to go back to this one again, I did ask Shannon, whatever became of this project, and it turns out that in 2018 so it had run for 20 years. There was an interview being given in the room and the noise of the compressor was bothering the person who was doing the video and the audio so they pulled the plug. I forgot to put the plug back in so what happened, well it went through a normal defrost there was a puddle of water on the floor in the morning the packages were fine, nothing happened. But the collection manager was new. She was young, and she made a decision to transfer the collection in 2018 over to the SI archive which in the ensuing 20 years had built a new cold vault so they're so there's a continuity of care. The region freezer did its job for 20 years, but now that those those materials are now in a dehumidified cold vault, a bigger vault over at SI archives. And I'm going to skip that one. Lastly is what I'm working on now, which is, I've never done the container method, the packaging method for a small scale collection and by small scale I'm saying you know 10,000 20,000 negatives. These are not my images, but it's not a huge amount of real estate, you don't need to build, you know, the iron mountain cold vault if all you've got is, say 100,000 negatives to deal with you can deal with them with region freezers. And so. And this, this is the new freezer I put in, and the containers are took me a while to find containers I really wanted to use but these are from a company, a USA company called iris, they're called the weather pro series may have. And this one, the one over here that's a letter size file container, and the other container just so happens to fit those drop front boxes very nicely to up so eight into a box. So that's the way I'm going to run my second freezer because we still have more materials that have to go into cold storage and I'm sad to say I should have gotten around to this earlier, but it's giving me time to think about doing it. I really don't have to do a lot of repackaging. So there's an advantage to containerizing it, they are sealed containers that got a gasket. And not only that, but the reach and freezer if you think about it, it's a sealed cabinet. So if you look right there. That's a just a pouch. It's a microfiber cloth pouch filled with silica gel, put three or four in. And I'm finding that I can regulate the humidity, even at minus 20 degrees fee I can regulate the humidity, just with changing up this desiccant. I, my calculations say that desiccants probably going to. Every year, I'll just recharge the cabinet. It's, you know, it's low use it's not like you're going in looking for food every day. There's no food in that freezer never will be. So it's, it's, it's going to maintain its, it's passive climate conditions for very long periods of time without me having to do much work. So, I'm going to try to wrap this up in five minutes. I just want to show you that the way we analyze moisture content and materials is the typical material science approaches to do what they call a moisture sorption isotherm or absorption isotherm. We call it either way. It is what it is, is if you, if you condition the material to a certain moisture content, and you hold the temperature constant when you do this, you get a line of constant temperature, but you get the moisture content versus relative humidity ship. These are all equilibrium conditions. And what I'm pointing out here is what we learned through another method I'm about to show you is that it's a family of temperature curves. So if you really want to know what this is like at minus 18, well, it's going to shift and it's going to kind of follow a line like that. This is called a type two isotherm and what's important about that is books would cellulose acetate of the photographic gel and they all follow this type and shape of a curve so it's called a type two isotherm. So look at gel, you just your garden variety silica gel follows a type one isotherm so it goes up a minute rolls over. But that that's more work to do than what I did I was looking at sealed containers I wanted to say hey I've got a microclimate it's a box of photographs. So it has its own sealed conditions, especially if I put it into a container or or I put a Ziploc bag around it. And I, I thought well why don't I just take this data, it's the same data it's moisture content of the gelatin, it's relatively human temperature, but I'm taking the data differently. And you can see that when you so you're plotting a line of constant moisture content, not constant temperature. So you just flip the scales you transform the same scales but you're just looking at them a different way. And what that told me is that this is going through a phase transition where this is kind of acting like a saturated salt solution whereas below a certain point, it's acting like a linear relationship. It turns out that at the time I was doing this work, I was, I was taking a polymer course at Johns Hopkins University and the the professor mentioned glass transition temperature and I've actually never heard of it before. But, but. So when I found out what it was I went back and I said, Oh, I know what this is. And so basically if you take a lot. I went back to my data and I said if I draw a line that follows the, the flat slope here and then another line following the linear slope up here, and we look where it bisects if you drop down, guess what you get you get the glass transition temperature. So you can see that glass transition temperature a photographic gel and it's different than polymers that are not not really very hydroscopic things like polyethylene have like one glass transition temperature by the way polyethylene is that minus 50. That's why a polyethylene bag still seems kind of rubbery and stretchy, even when it's in a freezer, because it's still above its glass transition temperature. Well with photographic gelatin, it's moisture content dependent the higher the moisture content that lower that point where it switches phases from hard dry polymer into gel state. And so that so when you look at something like silver mirroring in a black and white photograph is a very common conservators are well aware of it but when you when you look at what the text. is because it's usually described this way it's well the silver particles oxidized, which forms silver ions, the silver ions migrate to the surface of the gelatin, and then they get reduced back to silver.  But there's got to be more to it than that because some of them, some photographs I've seen just don't have the problem others do. There's other issues like whether they're chemically tone or not but if you're just talking about a straight process black and white gelatin print. What's going on here is that that over the life of this print and this is about a 95 year old print. This is a picture of my father when he was a boy. I only came across it recently, it already had this silver tarnish but what this is telling you is that at some point during its history. It got into human climates. You know, maybe it was 25 degrees C at 75% our age, when the gelatin goes into the gel state because of that transition. It allows the silver ions to freely diffuse and freely migrate. So the moral that story is if you never, if you always take pains to keep the gelatin in its dry state and not in its damp gel state. You're not going to get this effect and that's why some photographs just don't have the problem and others do. Likewise with the fair typing the fair typing is exactly the same problem that gelatin has moved into its gel state because there's too much moisture content. Very quickly, I'm going to try to wrap some things up here. This is kind of the way I worked out these moisture content relationships with photographic gel and I was using powder gelatin supplied by Eastman Kodak, put it in a K mark pressure cooker $20 added $5,000 worth of children mirror and then I was able to look at the relationships between and these are equilibrium state tests and look at the differences between temperature and our age where the things settle down. That's how I developed the moisture content isoline plots you saw, but whenever the experiment took the took the gelatin up above glass transition temperature. What I would end up when it when I opened the pot after the experiment is I would ended up with it glued to the pot. I had to, I literally had to just rinse it out with very hot water. This is my friend and colleague Dr. Mary and Macklin Berg, one of the team that was doing this research. So we get to physical limits and physical safety limits because this is still I've surprisingly enough this is still an issue today of what are safe and allowable limits and there is still apparently I just, I just saw this in a, in a global forum in the transformation post just about a week ago that there are still advocates for very flat lined, very stable conditions. And the problem with that is that when you want to do cold storage. Again, you have to invoke the big cycle. So how do you determine that that cycle is safe. Well you can do empirical experiments and that's what Eastman Kodak did when they did back in the 1970 Adelstein Graham and West publish a paper preservation of motion picture films having permanent cycles. So dates back to 1970, and they did a freeze thought cycling test on the motion picture film and they, and they check physical properties before and after and they said we don't see any difference, ergo it's safe. That's a very good empirical experiment. It gives a lot of reassurance but it always begs the question well what if you've done 510 cycles or 520 maybe it might have broken that. The real way to get at this is with modern engineering techniques find that element analysis and that's what we were doing in the lab in the 1990s. This is Marion Mecklenburg. He was doing paintings, the construction of paintings I was, I thought when I saw his work I thought, and I said to Mary and I said you know photographic materials are so precisely coated that I can, I can measure these properties and these thicknesses extremely accurately using cross sectional micro photography and so forth. And we can build the model with very precise materials, and then I can test the model. This by the way is me with the strain gauges and the instrumentation to do this so it's all material science, the driven. The result was after I had all those material properties coefficients of a coefficient of expansion humidity coefficient of expansion stress strain, all that kind of material science that goes into this computer model. The computer model predicted that if I were to take a piece of see the chrome of certain dimensions, it was two inches by about a half inch, and I was going to desiccate it I was going to start an equilibrium RH at 70% I was going to go down 20%. The model predicted that the forces on that gelatin, because it's restrained it's adhered to that base, the forces were over 6000 psi that's huge epoxy glue generally starts to yield at about 1000 psi gelatin goes much higher but by 6000 it will start the yield it'll go into plastic deformation. This is where crack propagation ultimately will start. So it may do 100 cycles it may do 200 but at some point sooner or later you're going to see cracks in the photograph and if you look at old photographs you see plenty of them that have cracks. They were stressed too hard they were they had too much of a humidity cycle. The computer model also predicted point to deflection. I made, I made the model, I physically built that that see the chrome, see the chrome by the way is polyester not acetate so it's jealous and I'm polyester. So the model worked precisely the end result and I'm about to wrap up here is all all that material science that we did in the 1990s. It culminated in basically my, you know, my treatise tacked at the Cathedral door it was like put everything you learned into a diagram of what is safe and allowable and this great area is the safe area of cycling. As long as you stay in that area so you might start with an object at point B 60%. In the field system what it's going to do it's going to cool down and end up about 40%. That's the physics of it. But now it's at minus 25. It's still safe. And when it comes back out it's going to walk up that line. And if you start with something in between maybe 40%. It's going to it's going to stand this on it's going to go down here as long as you're staying in this zone, and you're staying away from this condition over here. You basically, you're basically safe. Everything. There are forces that are that are working on these materials as they cool down and come up, but they're all forces that keep it in what material science called the elastic regime, they're classically deforming. So, if you think about what is plastic deformation think of a manufacturer stamping out a sheet metal and forming a fender, they're stamping it in their plastic, you can get away that once twice, but you can't just keep doing it otherwise you start to build cracks and voids and paper materials. The same thing if you think about fold endurance testing. Same thing you can fold a piece so long but you're actually plastic lead forming it so on the one hand, you're working the piece and would to give it a crease that you want it to have. On the other hand, you can't keep doing it. This was the one last slide and I'm done. So, so the only other caveat here is the staging the CMI packages were designed to be self staging you don't need to worry about this but if you were to load something in a kind of a strange way so in this case I took a drop front box, no inner bag, and I took a data logger so think of the data logger is like a block of film like a small wrote motion picture film it's got thermal math. And if you just put a zip lock bag around it. What's happening is that the temperature gradient between the, the empty paper box and the massive film in the corner. It builds too high of a temperature gradient if you just bring it out of the freezer and lay it on the table. And so the data logger showed that we were actually hitting condensation when we did this. Doing the same exact experiment with the same exact setup, and just adding a picnic cooler some insulation around it and I was able to clip that to only 47% so no condensation. Aging may be needed, depending on the box the materials. And, but it's not hard to do, you can do it in a number of ways but using some insulation is a very simple way to do it. We talked about the instrumentation earlier. All I want to do is acknowledge Shannon parish at the Smithsonian Institution that Thomas Mosquita and at the Norman Rockwell Museum and Henry Wilhelm Wilhelm Imaging Research for the help that gave me getting this presentation together. All right, Robin, it's all yours. You did great. And that it's a lot it's it's a complicated issue as we knew so we appreciate you taking the time and kind of taking it into biteable chunks of information. There are two questions that I wanted to hit it's 158 right now so we'll do like five minutes of Q&A. One was, do you have any concerns about the plastics of the storage boxes, assuming they're HDPE or PE in terms of over time and I thought that was interesting just because you can put these plastic storage boxes in there but are you ever worried about things becoming brittle or gross within the actual freezer itself. No, because the materials in sub zero are also benefiting from the cold. So they do get more brittle but I did test them to see can I handle them. Am I going to, is it going to be so brittle. These boxes that I showed you are polypropylene now polypropylene is going through a phase transition around five degree C. It is getting stiffer. So it's going through a TG but TG is not like melting point, meaning it's not a discrete condition there's a sort of a, there's a range where the molecules are reorienting and so by the time it hits minus 20 it's still it's stiff but it's still workable and still open the handles I can still work with it. And so from the chemical standpoint, they're in low temperature environments. So if you ever see it, if for any reason and I would imagine it's probably more handling sooner or later to say you know this box has kind of been beaten up a bit. Just replaced it it's not, it's not, it's not a collection material it's, it's just a, it's just a sacrificial container, the same with ziploc bags if you ever think the ziploc bag might look a little worse for wear, just replace it. Not a big deal. Okay. That's a super good point and I mean this is from someone who up until the last couple years ago kept like rewashing out plastic bags and keeping them at a certain point I was like, Why am I doing this? The other, the other question I thought was interesting is because I would be in this boat, it says cold storage novice here we inherited two very large cold storage freezers. One died, and the parts are no longer available to fix. If we lose the other one, what are things to consider if we have to acclimate the collections and not return the photo collection, and they've had parentheses negatives to cold storage environment. Do you have any thoughts on that because I could see that happening to a lot of people, like it dies and then you're like what do I do. Yeah, basically, if you've got a proper package on them. It's just a it's a warm up period. It's no different than if you are want to use the package and you pull it from the freezer. It's just a warm up cycle. And you know, obviously if it was a freezer full of food, you've only got so many days where you've got to get the material back into cold storage otherwise it, you're going to lose the food. With the photographs it's just a time out of storage thing look it takes you a week. It's a week of out of storage. It's just aging normally at that point. So I think the only thing you want to make sure of is that obviously if a freezer goes down, and if it's a manual defrost freezer and if you've got water inside it. At some point you may want to pull the packages and just put them in other containers or set them aside, let them warm up and then deal with the with the say the water on the floor like American history had to do. Get the get the freezer repaired and back online or replace it and stay it takes you 10 days to replace it. You've got to have contractors come in and fix it. So you have to be vigilant. There's no free lunch and it's true even if you don't do cold storage. You know I'm constantly vigilant on is my roof leaking. Do I have pipes that are, you know, freezing in bitter cold temperature we had minus 15 degrees Fahrenheit last week, and now it's spring like but at that point, I ran some water just to make sure that some of my water is freezed. So you have to be vigilant about any kind of active environmental control whether it's room temperature age back systems or whether it's freezers. So I think you just have to look at it simply from my maintenance point of view, but as far as the packages and the, and the product. So where things can actually get more out of hand is if you do like with a big ball that's dehumidified and people don't do the maintenance, or a sprinkler system goes off above the ball, and then the water gets in. Well at that point, I'd honestly recommend to people that if you're going to do a dehumidified ball you may also want to consider those cabinets, you or at least containers, because they're going to give you a second line of defense that if anything goes wrong in your collection that happens to pour water into your cold vault, they're not on open shelving and in paper boxes, they're in containers that will at least give you one line of defense against water damage and honestly with photographic collections, water and moisture damage is kind of the number one problem in my in my opinion, obviously you don't want things to get hot either but and certainly not too desiccated or dry but but honestly with most photographic collections the materials are the ones that are in the worst shape or the ones that have been exposed to extremely damp conditions or direct water from leaking pipes, bad roofs and all that. That makes sense. There are still some more questions coming in but it is after two. So what I'm going to do is I'm going to pull the report for the questions I'll get them to mark. Luckily people's names are connected to the questions. So, but also if you have additional questions for Mark, please feel free to email me at c2cc at cultural heritage.org and we will be sure to get those to him. Any final thoughts at all mark about today or today's program. So, I guess the classic thank you for having me, and I did. I did enjoy it and I hope I know it's a lot of material. But it's, it's, it's, in my opinion, it's just grounded in really solid engineering. So it's, it's, it's left beyond. I just don't want to give you opinions that I think something's okay I really wanted. I really want to have facts that the backup, you know, evidence based data really. Yeah, and I think you definitely able you did that for us which is greatly appreciated because this is a complicated topic but as your studies and your experience have shown like it does help with the long term preservation and storage of objects I think that's really Yes, and my collections are already bearing fruit and so are many others. It actually got started 40 some years ago I think the earliest cold ball was the Kennedy Library because the Kennedy Administration was the first presidential administration that was that was in color chromogenic color acetate base. So, the Kennedy Library accepted Kodak's research, they didn't question all the cycling things they just accepted the cycling data that Kodak provided and they went ahead and built that cold ball. So zero minus 18 degrees C dehumidified in 1982 when the new building came online so. So we have, you know, 50 plus years of experience with cold storage of photographic collections and paper based records handled but they behave essentially the same. So it's, it's what you want to try to strive for if you're talking about highest standard of care and I would simply say these are this is all gradations it's higher and higher and higher, but you just have to stay within the physical limits you don't, you don't want to get to dry like 20% our age at room temperature, those that'll cause cracking so you know basically stay in your lane, and it's safe, and they're for small collections there are passive ways to deal with it. So that the more small collections go into cold storage the more we're going to have a better history of the 20th century. Yeah, I would completely and utterly agree and looking at the comments from the audience they would agree as well. So there's a lot of thank yous for presenting today. Okay, well I'm going to go ahead and sign off for today. Thank you again Mark. Thank you to FAC and I'm a less for supporting this program as always, I will be trying to get the recording up with by Monday at the latest possibly Friday, and don't forget to check out our March program on exhibiting photographs will be starting to announce some of our later spring programming probably later this month as well. So everyone stay safe, and we will see you next month. Thanks again.