 Susan said, I'm Jenny with Heritage Preservation, and we're so glad you're here. Let me go ahead and just give a quick introduction to this community and these webinars, and then we'll move on to our topic. Heritage Preservation is moderating the Connecting to Collections online community in cooperation with the American Association for State and Local History and with funding from the Institute of Museum and Library Services. The site is designed and produced by Learning Time. The goal of the online community is to help smaller museums, libraries, archives, and historical societies quickly locate reliable preservation resources and network with their colleagues. In developing the community, we have drawn on many resources that were developed for the C2C initiative, including the bookshelf and the Raising the Bar workshops and webinars. Links to these recordings and resources are filed under our topics menu on the site, and today's recording of today's webinar will also go there. About twice a month on the online community, we feature a particularly helpful preservation resource and host a webinar like the one today related to it. The resources, again, will be filed under our topics menu and can be accessed by clicking this photo on our web page at ConnectingToCollection.org. Today I am so pleased to welcome Stefan Mahowski, I think I got that right, who is joining us from Brom today. Stefan is a senior conservation scientist with preservation services at the Canadian Conservation Institute, Department of Canadian Heritage. And today Stefan will walk us through the institution's light damage calculator. Thank you so much for joining us, Stefan. Would you mind just telling us a little bit about yourself? OK, thanks, Jenny. I hope everyone can hear me all right. I'm Stefan Mahowski. I was trained initially in the sciences and physics. Then I did a master's in conservation. So I turned as a conservator, but after that I was hired to be an advisor and researcher at the Canadian Conservation Institute. Well, I've been now for over 30 years. My job is primarily to develop research in order to give cost-effective advice to Canadian collections that are in public institutions and public collections. And that's why we developed our web page and the material on the web page to try and address that part of our mandate through the web. And the light damage calculator is one of the most recent tools that we've put up on the web. And we hope to do lots more. Thanks. Great, thank you. So before we go into the presentation, we often have poll questions. So we have a few today. And our first two questions will be door price questions. So if you answer the question, we'll pull one person at random from each question to win a fantastic resource. I do have to warn you, you do need to be a registered member of the online community to win so that I can email you and let you know that you won. So our first question, a really simple one. Let me just pull this over. And it's just have any objects in your collections been visibly damaged by exposure to light? And your choices are yes or no. And I cannot tell. And we have an outstanding 100% with yes. Let me know if you can't see that. But you guys should all see the results of this poll. So wow, 42 people, 100% say yes. They have light damage. Our next poll for you guys are what are the most common sources of light exposure in your institution? Is it direct sunlight, indirect sunlight, flash exposure, fluorescent lighting, or other? And I'll give you a second to fill that out. Oh, sorry. So it looks like most people are saying fluorescent or tungsten halogen lighting. OK, great. So our next, my third question today is, does your institution currently measure light levels yes and no, or you don't know? So we have a good mix. We've got quite a few yeses, but we also have a good number of noes. A few I'm not sure. And then our last question today are what policies does your institution have in place to reduce the potential effects of light exposure? Please feel free to choose all that apply. And there's quite a few there. From locating objects so that it minimizes their exposure, blocking incoming light, using incandescent lights, rotating objects on and off display, light monitoring, determining an allowable light level for certain rooms and certain objects. And then of course, we don't currently have an option or we don't have policies regarding light. Looks like a lot of people don't have policies on how light is treated. And then also, a lot of people are blocking incoming light. Give that just a few more seconds. Lisa was telling us that they can't choose more than one. Oh, no. So if you'd like, I'll pull this aside, change the poll, and then pull it back up on this corner. And the audience can continue to answer that while Stefan goes on. OK. Actually, Susan, I think that's OK. I think we get a good idea of what people are looking at. So and if you guys want to continue, you're more than welcome to talk about those policies over in our Q&A, which would be great to hear. But Stefan, let's go ahead and move over to you. And you want to share your screen, correct? Yes. All right. So Stefan's going to walk us through the calculator live. There you go. You can be all set. I hope everyone can see the home page of the Canadian Conservation Institute. And if I don't hear otherwise from my moderator, I will continue onwards. So this is the home page of the Canadian Conservation Institute. And you can either Google Canadian Conservation Institute, or I could turn on the navigation bar for a while. I don't know how many can see that. www.cci-icc.gc.ca The home page, there's various access points to what we have on the site. And for the light damage calculator, there is a link directly on the home page. So I've got my cursor over it. I'm going to go to it and have the pages responding. This is the opening page of the light damage calculator. Actually, sorry. It's the opening page of all the tools and guidelines, one of which is the light damage calculator. There's also environmental guidelines for these things and more break and so on. Let's go to the light damage calculator. Here it is. There is an introductory text, which you can read if you go back to the tool. But I'm going to take us straight to one of the first of the three different pages. There's fading of a single or fading of a single color into three different scenarios. And there's fading of a collection of colored objects. I will point out that these alternative pages here are in concordance with our government's accessibility requirements so that anyone who is using a reader to go through the web page and is blind is able to get the numbers out. But we'll be looking at the one that presumes you can see patches of color on your screen. So this is the beginning of the fading of a signal color. I've expanded the page quite a bit and turned off full screen on so you can see better. But normally, in your own browser, you'll probably see more of the page and there won't be so much need to scroll up and down. But I've said that quite expanded now so that everyone can see it. The default values are within the color and there's red, alizarin paint. There's a number of different paints one can choose in here. We're going to go straight to seeing what happens with these default values. Whenever you change these numbers, which are the display settings of your exposure, planned exposure, you will need to hit the compute fading button. And another section of the page will show up. So now what we see is this band of red color, which is the alizarin. Well, those of you saying what is alizarin and why should I be interested in it, at the bottom of the page, there are what's called the colorant comment and the colorant notes. The colorant notes are rather more technical. They explain where we get the numbers from to do the calculation. But you would be interested in the colorant comment. So for example, for alizarin, it says, used in watercolors, oil paints, and acrylics invented in 1868 and replaced the natural pigment matter, which contains alizarin plus purple and tends towards a slight blue tone. So it's used in watercolors, oil paints, and acrylics. We realize actually looking at some of these texts, as I do now, reading this one, thinking I should have a sentence saying, widely used in watercolors, oil paints, and acrylics. Probably the single most important red colorant used in paints and acrylics and so on. This area of the patch is the original color estimated. Current color estimated, we'll talk a bit about that later. Right now, we're assuming that this object is in the museum and has not been faded before. And then this is the degree of fading, quite a small amount of which will happen with what? Whereas when the default settings are 50 lux, 8 hours a day, no flash, every day of the year, for 100 years, what happens, for example, if you think your museum is more likely to have typical office lighting at desk level? This is the kind of level of intensity of light that people are used to in their everyday life. We're not even going to talk about going down a direct sunshine yet. So typical office lighting. And remember to click compute fading. And now we can see dramatic change in the color. So just to review, I've said it's a lizard paint. Hasn't faded before. We're averaging 700 lux. And for those of you that don't remember lux, it's just typical office lighting or kitchen lighting and home lighting. 8 hours a day, every day of the year, for 100 years. And this is what we expect the lizard will look like. Now these two patches represent the difference when you remove the UV with a filter. So the most damaged, most faded patch is the predicted damage by light with UV, which is equivalent to daylight through glass. It's also equivalent to some of the worst forms of fluorescent lights if they don't have a UV filter. And this patch of color, slightly less faded, is the predicted damage by light with all of the ultraviolet removed. Slider up here now allows us to play with turning the fade on and off. So you grab the slider with the mouse and move it back and forth so that 0% of the fade is no damage. And if we go up to the full fade, this is the full damage. For those people that like to look at the calculation in terms of the total amount of light exposure, there's this number here, which is 204.4. And then a capital M, a little l and x and h, which is short for megalux hours. We won't go into exactly what megalux hours are for those people. I'm not familiar with them, but it's the conventional museum way of counting up lux hours. The M just simply means millions. So it's millions of lux hours. We do have a web page on this site, which is a chapter on lighting UV, which, if there's time, I will briefly introduce you to. And in the glossary there, there is a definition of this term for those that forget. But really, you just need to know that 100% of what you set up here is going to cause this amount of damage to this particular color. So change this back now to switches, recommended bones and galleys as a benchmark, a starting point. You can see on this list of lux levels. For those people that aren't familiar with the numbers, I've put in phrases to describe where they are. And if we start at one lux, there's the definition of a lux. It's how intense the light is from a candle at one meter, or that your arm's length. So the definition goes back to literally a standard candle 100 years ago. It's been made more modern, but if you lose track of what a lux is, it's candlelight at the length of your arm. For moonlights, 0.1. We need about 10 lux to see color at all. At 50 lux, young people start to see objects well. At 150 lux, the young see dark objects well. Unfortunately, it's 500 lux of the old, and I have to begin to include myself amongst that group. We need 500 lux to see many objects well. But let's go back to the kind of benchmark of the most conscientious, careful museum of 50 lux, compute the fading. And we can see that in 100 years the lizard is quite a modest amount of fading. Checking my notes and my own little script to see what I said I'd do next. Yes, I said, let's pick a different colorant. And I'm going to pick one which I know is quite fugitive, but also which is quite interesting for smaller museums across North America, especially. Blue indigo, Carmen, die on wool. It's not that I expect everyone to recognize that. So we go down to colorant comment. And we see the current comment hasn't changed because I forgot to push compute fading. So every time you change any human in the current, you've got to click that compute fading. So this is the color of also called self-analyzed indigo. It's a greener-shaped indigo, discovered 1740. It's much easier to dye than indigo, but much less like fastened runs in water. This is where I get interest in, I think, for many people that are online right now. It's very popular in 19th century samplers. So if you kind of recognize this greeny-bluey tone in wool threads used for embroidering samplers, it was very popular apparently in 19th century in North America as well, samplers. So this particular color, which tends to shift green, Daniela, which we don't show in the cat curry, we just show it as fading. This is probably in a lot of samplers from 50 or 100 years ago. So we can see now that even at 50 lux, this is an awful amount of fading in 100 years. And I'll just wave the slider because this is my favorite part of the tool, is waving the slider. I'll try not to make everyone dizzy. I mentioned here that we also used the height of the color to represent fractional loss. We tried looking at this thing, making this design, where the patches stayed the same height. They didn't change their shape, they just faded. But when you have small amounts of fading, like this, for example, not all computer screens and poor projectors make it easy to see that color difference. So we threw in height as well. So there's a colorant in a sampler, which we can expect to be very fugitive. Well, given that over half of you said you've seen light damage in your objects, we're going to explore now the question of can this calculator tell me something about things which are already partly faded. And so this is where we go up to here and say, so the color currently remaining. Now, this is a gas. It's an estimate. Maybe you've seen a section of the color that's protected. Maybe you've flipped the sampler over so you can see what the color is on the back side. And you're saying, I think it's about 80% of the color is left and we compute the fading. And so this is what the calculator is doing now. You're telling that this is probably the original color. This is roughly what I've got now today. So if we turn the display down to zero future exposure, we have what we have today. So again, repeating from left to right, this patch is the original color, estimated. This patch is what you have today. And the next two patches are what will happen in 100 years at 50 lux. So here's a color which demonstrates that even with 50 lux, which is a very low intensity to achieve, especially in a stark house where you may not have full control, that's not a guarantee that the colors will last forever. There was a tendency sometimes in museums and galleries to think that if I use this really low light level, which conservators or museum community recommend, somehow the problem goes away. It gets very much slower, which is a good thing, but it doesn't go away. So this calculator allows you to explore all the way from colors like this, which are extremely fugitive. And now let's leave the same setting and go to, remember we went back to, now let's look at Indio in another situation, Navy blue uniforms, military of the Navy, would be blue indigo on wool, and I'm going to go to indigo wool, heavy dye, keep fading. Now there's no visible change to indigo and wool after 100 years at 50 lux. So it's gone completely to the other extreme in color sensitivity. There's a reason Navy blue uniforms look Navy blue until they fall apart and get moth-eating. They don't disintegrate, but they still fundamentally Navy blue. And we go down to comment. This example estimates reduced sensitivity. Indigo when dyed to a heavy shade has a Navy blue textiles, and then see the entry on blue indigo wool for general information on indigo. We would actually have to go up to, suppose you're a historic house and you've got a Navy blue uniform and you think maybe you are up around 1,000 lux, and if you compute the fading, this is what you estimated there. And this little drop down is 100 years. So indigo really is remarkable. We have to actually say, where was it so popular? Well, you could actually wear it outdoors, 30,000 lux average daylight hazy sky. And if you were a sailor in Her Majesty's Army for 30 years and you wore it outside most of the time, you would start to see some damage and color loss, especially if you're outside and it was getting UV. But compared to the other colors, this is remarkably robust. OK. I think that's what I want to do on that particular page. I'm doing all right for time. And now I'm going to go to the light damage calculator, the introductory page. And I'm going to look now at the next page, which is page 2, which is fading with single current and through indigo carbon again, partly because it's more dramatic and partly because I suspect a large number of people listening in the summer in that collection they have this particular blue. There will be 50 lux, 8 hours a day, every day of the year for 100 years. And these are all default to the same value. So let's just make sure we're clear on what we're doing. Here are the three scenarios and the degree of fading across all three. There's actually three different blocks here. So I'm going to turn the middle one on and off, for example. That's scenario number two being turned on and off. And this is scenario number three being turned on and off. And here's number one. So I'm hoping that now some people have watched the button going by on flash exposure and saying, is there a big deal with flash? Why have museums spent ever since the invention of big photographic flash, why have they banned it in museums so often? Is it correct that it's not a good idea because it will fade objects? Well, let's add it here. We've got the 50 lux. We've got the 8 hours a day. Let's add, for example, here we see we have four options, amateur electronic flash, typical auto setting. And let's say you're an incredibly popular museum with 1,000 people popping their flash in front of each artifact every day of the year. On the other hand, you might wonder, what if I don't allow the general public to do it? But I have a professional studio flash, which I have allowed in when I digitized the collection or when reporters or somebody wants to do it. And I'm going to set it very conservatively to a big studio flash very close up to the object. But I'm saying I would never allow that more than one day a year. So now we can compare those. Let's hit compute fading. And in fact, I don't know if you can see on the screen there is a tiny little drop here for the addition of 1,000 tourists flashing every day. You can see it in the numbers here, the calculated exposure. This is the 50 lux after days, 14.6. The flash adds 14.9, the amateur flash. And the one big fat studio flash per day is actually less. It's adding 0.15, so making a total of 14.75. And there are these tiny differences in these numbers. I haven't mentioned these numbers. These are color change using the units that are used for measuring color. A big color change in these units might be 70, 80, 90 units. All right, so that's not very important. Well, let's see what is important. Suppose we said we're going to reduce this to, well, let's change it here. Let's say we're going to rotate it and do it three months per year. So the third scenario is only out there three months of the year. So this is what happens when you change to three months of the year. So I think you can see that whether or not you tell people to use the fake flash photograph. From the point of view of fading, I personally don't like flashing museums because it's distracting and disturbing. And some people don't like flashing museums because it reduces sales of postcards in the shop. These are all good reasons. But it's not about fading of the artifact. And in the old days, when flash was a huge magnesium pile of magnesium, it was a fire hazard. And then through so many years in the 50s and 60s, there was a garbage hazard because people were popping little flash bulbs all over the place. So those are issues. But it's not a fading issue. And that's where we built the flash option into the calculator so people could look at that. And I'm going to put my script here and the flash. Use the slider. This is a bit of a long page to use. We did. But for those of you sitting back thinking you could design this page better. And probably there's lots of options that would be better. Within issues of guidelines for government web pages and accessibility and keeping things fairly clean, this was the end result. And as I said, when you view them in your own browser, they're not quite so enlarged or magnified. You will see more of the page all at one time. We are going to add the feature of creating a report. People have said it would be great if this thing could push a button and give us a PDF report, which shows the color patches and so on. It's a bit of a nightmare to work out within government guidelines what's possible to generate. But that's certainly one of our intents. Let's go back now to the home page of the calculator and look for page three, which we hope will in some ways be the most popular and the most useful page in a way, which is collections of colored objects. Now, at the moment, we just have three collections in here. And this is a good moment to say both in the list of colorants and in the list of collections here. This is just a preliminary list to populate the first version of the calculator online, which just went up a few months ago. And within another six months, we hope to have a much more extensive list of colorants entered into this. And we said we would welcome any suggestions people have for collections or colorants that they think are missing, or that they would like to see in here. We do have data on natural history specimens, on insects, on butterflies, on all kinds of things. It just takes a bit of time to massage it into something that's actually usable in the calculator and that we feel confident is reasonably reliable. So let's look at first textiles. And within this page, nothing happens when you first push compute fading in terms of exposure, because everything is set to zero years. So this is the collection. We can look at it without any fading. I picked four colors to represent from left's most fugitive, most sensitive to the right, the least sensitive. So we've seen the examples of the two individuals that are at either end of this, the indigo on the right and the carbon on the left. So the collection comment, from right to left, the most durable historic dye has always been indigo, especially on wool and deep dyeing, has used in naval uniforms. So you know that already. Next is the other important military color, matter red. Also popular in cotton for quilts throughout North American collections. Some of you textile collections may know this as turkey red or Constantinople red. It's certainly very popular in quilts. Logwood was long used for blacks in various fabrics. In about the 1800s, it became the moon black dye for weighted chokes. So one of the Victorian chokes that are black, the parcels, addresses, morning clothes, most likely done with logwood. And then indigo climbing was invented in 1740, widely used in shampoos in North America. Those of you who want to know much more detail in the major references we use for these historical and kind of history of technology notes is often the graphs book on dyes and colorants. I will show you, if I forget the moderator, maybe you have mind you, I will show you where you can find all the references on the web page for our sources of information. So let's go back to fading this collection. Let's say let's use our old standby of 100 years. So 50 locks, eight hours a day, every day of the year, 100 years. And future exposure with UV, nowhere, we're a reasonable museum, we plan to block the UV and compute fading. And now we see what happens to this collection of colorants. And I think this has been noted and observed in the conservation literature on fading collections for decades now. What happens to many mixed textile collections is they shift to pretty much the navy blues and some of the brick reds are left and a whole lot of the other more exotic colors, some greens and purples and blues and pale blues and so on are gone. So let me slide them again so you can see. What we're seeing now is the variation in sensitivity across the collection. The bad news is on the left and the good news is on the right and other things fall in between. The purpose of this page is to give a sense of what's happening to a mixed collection. It's also at the same time it's trying to give our best estimate of what is representative of the various kinds of collections. We could say now while prior exposure, let's suppose that actually it was in a hallway that got a certain amount of light, maybe 300 lux, but you know it's one of those hallways where it would get bright for maybe three hours a day. It was only for a few months of the year that it was like that and not everything was out all the time over the last hundred years may be things for on exposure for 50 years. So that's a plausible guess about what happens. So let's turn the future exposure off. So the slider is set for zero percent. That's the slider is only affecting the future exposure that you're planning. So now we're seeing this is the state of the collection if it's survived a hundred years of the light exposure and suggestion. And if you just wanna see what your collection might look like if you have a rough idea and you may know if the previous director of the museum was really irresponsible and the light was at 900 lux and it was doing that for five hours a day and they were doing it every day of the year and that director was there for 20 years and you had the compute fading and you turn off the future. You see that you're actually your sampler with the indigo, carbon, bluey green color. It's just not there. There'll be a ghost of the color left. The black silks would have been fading and we show here that a lot of these black silks using logwood mixtures will tend to turn a bit of a purple tone. Not necessarily as clear as this purple but in certain angles you'll see the purple and the red is turning to less than brilliant red. And then we'll see what the additional effect of your planned exposure for 100 years. So almost different kinds of non-introduction to the light damage calculator. We can look at the, there's one more point to make. Let's leave that all the same settings and compute the fading and actually the carbon lake which is really unfortunate is gone. Let's say the reason we still have carbon lake is it was in this dark house which in the hallway would get some moderate amount of light for a few hours a day. It was only seasonal that it was getting that light. The painting was not hanging all the time but it was maybe 40 years out of the last 100 years. And let's see if we, yes, there we go. We expect to see this amount of carbon left. It's plausible, we do see carbon in portraits in the 19th century. We also see portraits in the 19th century where the skin is dead white because carbon lake which was used for the skin is completely toasted. And then let's go back, we're looking at what's the future 50 lux every day of the year in the museum at 100 years? Is that such a bad thing? Well, it's pretty dramatic. We have to remember the lot of historic exposure for the last 100 years was intermittent. It was in hallways that we're bright for one or two hours but not the whole day. That the advent of electric light and constant display is a heavy burden on light damage. And so you have to understand that even dropping down to 50 lux is not going to stop this kind of thing happening to the Red Lake. You really have to say, I'm sorry, it's not every day of the year. You're gonna do what major galleries in Europe or down there elsewhere in the US or paintings, they really value. One month of the year. All right, so that's the, we're gonna fly back and forth on damage for one month of the year. Let's see, one month out of 12 is a big factor. Of course. One thing that's curious and may confuse people a little bit at the beginning is what about the UV, if there's prior UV, I say yes. And let's turn this actually out to prior exposure with overcast sky, compute fading. This is the original, these are what's left. Still pretty good. Let's turn on with UV and make it every day of the year and back up to eight hours. It's a street sign that's been sitting outside for 40 years. It's a tractor that was outside and Massey Ferguson and Massey Harrison, whatever, compute the fading. Pretty much not good. All gone. We have to back it off a bit and it all goes. And did it last 10 years and we can see. So the question is why we send the ultramarine and brown embers fade because in fact these currents don't fade when you read the current notes in Humber and Ultramarine. Both pigments are unaffected by light and UV, only the medium especially, oral is affected by UV and we'll chalk after long exposure. So we represent chalking of paints by a fading patch like this. You'll see the difference if I say no. It was very high light exposure before but there was no ultraviolet and we click on this and these things are fine. So when we look at a lot of paints, outdoors, automobile paints and traffic signs and so on, if they get wet in the rain a lot of the color comes back and that's because the pigment itself didn't actually fade that the medium does what we call chalking. It's disintegration by UV. All right, now I really am talking about the Light Damage Calculator and I'll take some questions or whatever from the moderator. That's fine, would you mind showing everyone you wanted to show the references that were used? All right, good point. So we'll go to the Light Damage Calculator. And then someone did have a question of what data sets were used to determine fading of colorants, so I, you know. Yeah, okay. In the fading of a single colorant, I'm in a list of colorants. I actually hid references. It was the simplest way to get the colorant comments. I have the list of references, the full references that have been used in stuff so far. So these are the full references. Now the citations, if we say, where did you get the stuff on Brazilwood and Cotton? Under the, there's the fading of Brazilwood. Under the notes, which are the most scholastic scholarly notes. Pat Field and Landy 1966 data fits, their ISO number two, calculator uses ISO two. ISO being the International Standards Organization, which is set up a scale for measuring or not so much measuring, but for specifying and measuring light sensitivity. So I got the Brazilwood data from Godfield and Landy 1966. I got the Adjustment for UV from McLaren 1956, and then the full citation was under references. So that's the way we did it. At the present set of data that's in there, excuse me, the present set of data that's in there is heavily dependent on two or three textiles studies, one of which is Pat Field and Landy. We will be publishing a more scholarly paper explaining in detail how the numbers were generated for this. So for example, the Pat Field and Landy paper, we did a lot of reprocessing of their data tables, because the original data tables are not so easy to interpret and needed to do what's called interpolating between their points. So I ended up doing Excel spreadsheets for all of that. I published data in that study in order to generate what we needed for the calculator, so that will be explained in the forthcoming publication. But it is somewhat uncertain business, and somewhere at the beginning of the calculator, aside from the legal disclaimer, there are several sources of uncertainty, ambiguity and identification of the current to the object, imprecise fading data for that colorant. Despite these uncertainties, the calculator can show the wide sensitivity range of colored objects and influence of exhibitions on the future appearance. And so for those interested, our current estimate of the kind of error is you could probably go up or down a factor of two or three from the estimates that are in there. So the estimates in the calculator are the most probable value, but this should not be used for kind of legal arguments about whether or not the color-faded 80 units or 75 units. We are simply giving museums a handle on, is it one month or a year or 10 years? Is it 100,000 bucks or 10,000 bucks? Great, thank you. So we had a lot of great suggestions on colorants to add, and I'll get those to you. One question is from Ansley, and she's curious about colors and photographs. Okay, okay. Let's go to creating the single color. And I'll give you the current answer. The answer I think you're really interested to hear is that one of the groups of data that I'm planning for the next set of currents is very much the photographic literature. There's a lot of studies published in sites like Henry Wilhelm's site and his book for many decades of data now, but rather tedious to convert it into the kinds of coefficients we need for the calculator because people's ideas are standardized like this, yada, yada, yada, yada, difficult to interpret. For now, what I would say to you, other than maybe check back in six months, is there are these other things here called standards blue number one, number two, number three, number four. This is the industrial scale for light sensitivity that's been around since the 1920s. It actually extends beyond eight now because so many modernizer are more robust. But one to eight represents what in the 1920s and 30s was considered the complete range of sensitivity and things haven't changed a whole heck of a lot. We can say, I know from the photographic literature that things that are light coat of color, ectocolor, all of the photographic material may have ended in color rather than chrome. Around ISO two to three are falling around a two, so you could put in a two and then this is the degree of fading represented by gray. So whether it's the man to die or the yellow dye or one of the other dyes, this is what we expect it to do with these exposures. So for now, until you see the photographic things listed there, for the more fugitive color materials, you can use some around it too. For the chromes, when Axe of Chrome came out, it was a big improvement. In fact, I'm using some of the articles by the researchers to show when we compared it with the blue standard that they could get up to four and five. So let's be optimistic and say, some of the best dyes in the best chrome materials coat of chrome, Axe of Chrome and so on. We're around a five, so you can put that in and you can see that for the same exposure, this is what we expect to see in the chromes. And let me go back to changing it to ISO number two for colors, we get this. The other thing I'm looking forward to doing with the color stuff is that under collections, we'll be able to use the three different dyes that were typically used in color photographs. And part of the reason the color shifts in a photograph when it's exposed typically shifts towards the blue is because the blue dyes were less fugitive. And that kind of data is there. We just have to sort out how much to fill the calculator with 100 different manufacturers, the products that have been tested, and how much to try and generalize it. Obviously, we want to try and generalize it for people with photograph collections. Those who want to do something very specific can go to these blue wolves and they can look up somewhere, there'll be a huge table saying this particular color material and this particular period of time in the 1960s was around a three, and then you could plug that. I hope that partly answers the question. You can use these blue wolves, sorry, they're making you dizzy. These ones, this is the key to unlock fading calculations when you know which rating your colorant has, but it's not listed in the particular list I have. But they're pretty fugitive of the color material. And black and white are better than eight. They're off the other end of the scale. The black and white silver gelatin, not a lot of the older forms of photography. Great, thank you. I'm gonna interrupt for just one second. We have about 10 more minutes left, so I want to make sure to get our survey up. If you guys, and I'm putting it over your face, I'm sorry, Stefan, I just want you to still be able to show us the tool. Yes, I'm just looking at my screen, and I forgot I'll only go to that. So whenever you guys have a chance, please just fill out the survey, and we really look at all the answers, and it really helps to shape the events that we have coming up in the future, so take a moment. But for now, we still have time, so I have some more questions for you. Okay. And some are not necessarily related to the light calculator, but more general questions about light damage. And I have one question from Chicago, Illinois. Does UV protective plexi, does it lose its effectiveness over time? The short answer is no. Okay. People have worried about this a lot and done some numbers of studies. Generally what happens to the UV absorbing plexis, it gets more yellow, it gets nasty, and it actually takes out more violet and more ultraviolet, because it's yellowing, which people find objectionable. But people have tried to looking at old, we've done measurements as well in old UV sleeves, and so we've never seen a loss of UV ability. Well, we have seen is that it starts to disintegrate and fall off, and then clearly it's letting light out. If the last inch on a UV and a fluorescent tube falls off because it gets brittle, and then it's letting it through. If kids start peeling your UV filter off the glass windows because the yeast is letting go, it's not effective. But we've never, I'm not aware of any study that showed loss of the ability to absorb UV and UV absorbing acrylic. Great, and then we just have one clarification question. Marcella just wants you to clarify slashes. She's wondering, do flashes really harm the collection, or is there really no difference between the potential harm of amateur flashes and professional flashes? Well, it's a relative question. So for example, what the calculator allows you to do is to see the modest amount of, and of course, the reason we allow you to select amateur flash versus a professional studio flash is that the studio flashes, I forget the numbers, it's 10 to 100 times more light. So one big fat bang off the studio flashes, 50 or 100 tourists with their digital cameras. Whether or not that's damaging, I can put it this way. It never begins to compare with a steady dose of 50 bucks, which is already very conscientious and low. You could imagine a bizarre situation where you said, we keep the thing at five bucks, people can barely see their feet. We let it come up to 50 bucks one hour a day, but we let people take flash pictures, eight hours of the day when they can't actually see it so they can go home and look at their photographs. I don't know any museum that's ever done a display like that, but in a situation like that, you might begin to see the contribution of all those flashes begin to be significant, but as I say that presumes that there's nothing, none, there's not even 50 bucks. So if the question is assuming we mean people using flash in a museum that's got lights on so they can see the object in the first place, the flash is not significant contribution to the fading. It's the same question that has risen in the form of photocopying machines on documents. If you compare the exposure to something that's on display and then it's insignificant, but if you turn it around and say we have an object which is so important to us, that C scrolls for example, that we in fact, some of them will never be on display. Now you then have to say, how many hours is it used by scholars under a desk lamp? And then this calculator would let you look at that, but in a situation like that, if nothing else is being exposed and the only exposure is a photocopying machine, a studio flash, then one can say those are the dominant forms of fading, but they'll still be incredibly slow and small. I noticed as I went back there was another question on iron gall ink, which is since I brought up Dead Sea Scrolls and things like that. Yes, there is a body of work right now that one of my colleagues at CCI season say is using what we call a microfade-ometer, which is a machine for measuring light sensitivity on microscopic samples. She is partway through a study of fading of iron gall inks and it's a complicated business. It will be the same with the artist's technique using sepia, and sepia or iron gall inks. They're mixtures of black particles, which are relatively stable, and a whole range of orangey, yellowy warm resins and so on, which are much less stable. So with inks, there's this situation where very often the core ingredient, the carbon, is not sensitive, but everything which gives it the characteristic of being a cool ink, a warm ink, an old ink and new ink, all those components are very sensitive. So that would be a matter of building that into the light damage calculator. I would see that as version two or three, maybe three or four, to start looking at that level of sophistication. Great. And a question from earlier on during the presentation, Scott, from Washington, D.C. is curious how will conservators determine what colorant was used? And then that kind of plays in with Cheryl's question about if you don't know the pigment and it's not a photograph, how would you calculate that? Yes, a good question and it's one of the things that the calculator is intended to address and is beginning to address under collections. So the purpose of the collections is to provide you with some basic information about, well, I have a textile collection between the 18th and the 19th century. And then we say based on this and this literature, this is probably the weakest and this is probably the strongest. And these are a couple of colors in between that you will find in your collection. But it will come down to a certain amount of historical knowledge on the part of the caretaker. One of the things we hope to also build in, for example, this some very nice work been published very recently by Dale Cronkite who works with the main George O'Keefe collection working with Jim Druzyk at the Getty Conservation Institute. And they've characterized or measured the right sensitivity of most of the pallets that they're worried about on their works on paper. And as soon as that kind of information's in the public domain, then I would add that to the calculator and you would have one of the collections would be George O'Keefe paintings from such and such a period. These are the currents that have been found and these are the right sensitivities that have been measured. And we know from the direction of the field is going, the research field that in the next five years there'll be a lot of that come out. We also, we can look at our historical studies that the pallet of major painters like Whistler or Degas are known for certain periods. So I need to sit down, take that artist's stark information, find out which sets to actually have reliable sensitivity data. And as soon as they get maybe 80% of them we know what they are. And we put that up as a color and collection. So are you right? The calculator will really become much more useful once it's including that kind of history of technology identification information, which is why we moved to the webpage so you can hide all of that stuff in the table. That's absolutely, I recognize that that's, we recognize that's a difficult thing. But I see the solution is emerging quite soon. Great. Just we'll do one more question from Dee. She's curious, and maybe this is the future of the light damage calculator. If there's a way that a tool could predict light damage apart from color change, she's thinking of brittle men or changes in fibers and things like that. Yes. In a way, the chalking of the permanent colorants like ultramarine and burnt umber and carbon black which only happen when you say yes there's UV. That is a form of disintegration from UV. And so I have been thinking about how to extend that to things like loss of strength in cells or tendering of cotton. Because you're right, there is literature there on it. It's just how do you make it accessible for the collections manager and conservator. I hadn't sorted out in my head whether it makes sense to try and do it within this particular set of pages or whether that's something that could be a related UV damage calculator which would be. Now that we've seen this prototype work on our page, honestly, it was quite an exciting moment to actually get it up after various struggles with technical issues and legalistic issues and so on. Now that we know it can be done, we do know those bunches of tools that colleagues in our institute have had in the back of their mind for years and which would work in an Excel spreadsheet or something and could be distributed that way informally but to be able to put them up on the web as a calculator tool. And then we see that in so many other industries and converters and so on. The most useful engineering pages for me for example are nifty little calculators to do the kind of stuff you could do by yourself if you went to a textbook and an encyclopedia but you'd rather do it quickly because someone else has done all the work. So yes, we would see doing that kind of thing but I don't think within this particular page. The chalking works as a visual output but saying that the strength has dropped off I think might be better just given as a number. Yeah, but it sounds like stay tuned to the calculator. It sounds like things were going to be added. It's going to become more robust. So that's, I'm afraid we have gone over our time today. Thank you so much for everyone who participated and for the questions we weren't able to get to please feel free to go to the discussion board and post them there. And thank you so much, Stefan. It's what time is it now? Almost nine o'clock? Yes. Thank you for staying out in the late hours of the night. Our next webinar is Wednesday, November 7th at 2 p.m. Eastern. Connie Bodner, Senior Program Officer for IMLS will walk us through the institution's new grant program Museums for America. And again, please take some time to fill out our survey that really does help us quite a bit in planning these events and I'll pull it over. And thank you so much. The recording of this webinar will be up as soon as we can on the connectingtocollections.org website and have a fantastic afternoon, everyone.