Watching Paint Dry - EWTS #001

Joe: Good afternoon, welcome to Enough with the Science. I'm Joe.

Senan: And I am Senan, and Joe's job is to think of new ways every week to stop me from rambling on and on about science.

Joe: I failed every week so far. So let's see we get through this one by failing again perhaps.

Senan: That's right, well today's episode is colorful language. And uh, that's what it's all about. It's a lovely colorful episode of Enough with the Science.

Joe: I suppose if there's one thing more interesting than watching paint dry, it's talking about why paint dries.

Senan: Yeah, I promise it'll be interesting definitely. So yeah, we're going to be talking about dyes and pigments and paints and also something with the intriguing title of nanoscale color, but more about that later.

Joe: Oh my god. Okay. So let's go the basic first step, obviously. Dyes, pigments, paints? Am I assuming they're different?

Senan: Yeah, before we get into that though, let's talk about why is it things have color in the first place. Like why do we actually see a color when we look at an orange orange or a lemon lemon? Um, so, white light comes from the sun and it's actually all the colors mixed together. And when you mix them all together, uh, they turn out white. Um, so, when that light hits something, uh, say an orange orange for example, um, some of the colors that are in that white light gets absorbed. And it's the ones that get reflected, the ones that the orange doesn't absorb, are what we see. So essentially the colors we see are the rejects.

Joe: Right. So technically an orange is all the colors that are not orange.

Senan: Yeah, that is it's soaking up all the other ones. And just uh rejecting the the orange one. So it's actually the mechanism for how that happens is really interesting. Um, so, you know, light travels as waves. Um, and like any other wave there's a thing called a wavelength, which is literally the length of one wave. Uh, and each color has a different wavelength. That's basically the difference between one color and another. But also, um, light has this weird property called wave particle duality. So it's not only is it made of waves, but it's also made of particles called photons.

Joe: Right.

Senan: And the different photons of of red versus photons of blue versus photons of green, they all have a different energy level. So they have they travel with a certain amount of energy in them these photons.

Joe: And just the waves and the photons are separate? The photons aren't part of the waves?

Senan: No they they are effectively the same thing. So they behave in both ways as if they are both a wave and a particle at the same time.

Joe: It's really mind bending that stuff. Yeah we might need to finish there for this week.

Senan: No we'll be getting onto quantum stuff in more detail another day, so I'm going to leave it just there for a moment. But anyway, um, as I said, different colors their photons have different levels of energy. So blue photons have a certain energy and red photons have a certain other energy and so on. Now, different materials, say our orange for example, um, the electrons in the molecules on the surface of the orange have something called energy gaps. So that is, um, for a given electron it will take a certain amount of energy to push that electron up to a higher level. Okay?

Joe: Right.

Senan: Um, and if the photon of a particular color that's incoming that hits that happens to be the right amount of energy to fill that gap, then that photon gets absorbed. So that basically is what determines whether a particular color is going to be absorbed or reflected when the light hits that surface.

Joe: Is it not just much easier to go "that's just orange"? I see orange. There it is. That's an orange orange.

Senan: Yeah I can smell it I just want to eat it. That's it. So yeah, it's all about the energy gaps of electrons and different substances different materials have different energy gaps in their electrons and hence they absorb different colors and reflect others.

Joe: I am never going to paint the house really in the same way again. Like looking at these colors like going right there's an energy gap there I need like...

Senan: And then by the time you're finished painting the ceiling you've got an energy gap yourself.

Joe: I've got well... I won't have an energy gap because I'll get someone else to paint the ceiling.

Senan: That's right. Let's talk about dyes, pigments and paints, because that's what it's all about, it's a lovely colorful episode. So a dye is a colorful substance that's dissolved in liquid. Now the important thing to remember from that sentence is dissolved. So it's a soluble substance that's able to actually dissolve into the liquid. In similar way that if you if you throw a bit of salt into a glass of water and stir it the grains disappear because they they have actually dissolved into the liquid.

Joe: Tea. Like tea.

Senan: Salty tea perhaps yeah it would be like that.

Joe: No I want tea.

Senan: Anyway, um, so, and then um there are some materials that particular dyes can bond to. So they're able to chemically bond to certain materials. So what that means is that if you want to dye a particular material you've got to match your dye to your material because only certain dyes are absorbed by certain materials. So for example it's common to be able to buy dye for dyeing your clothes that's intended to be used with cotton. And if you were to put in a cotton shirt and a synthetic say nylon or polyester shirt, the polyester shirt wouldn't pick up the dye at all but the cotton one would. So you've got to match dyes. Dyes are something that have to be matched to the material you're using them on and they're soluble.

Joe: Right.

Senan: Um, and uh they do tend to be less vivid than pigments which I'm going to talk about in a moment. Um, and they can fade over time. So they're less permanent kind of colors. Um, so pigments are insoluble. So they don't dissolve into the liquid. And they're effectively a dust. So it's a colorful substance that is ground down into a very fine dust. And um usually then it's mixed with a binder liquid because it's usually no use on its own as a dust. You want to use it to color something you've got to have a binder that it's mixed into that kind of holds it all together and and gives a nice smooth finish. Um, but the the colors are more vivid, they last longer, they're more opaque. So the dye colors tend to be transparent-ish whereas pigment colors tend to actually be opaque. Um, and paint effectively is pigment. So paint that you paint your house with, um, uh, the binder that the pigment is mixed into is a kind of a glue that dries and goes hard. Um, so that's essentially what paint is just a pigment with a binder.

Joe: Right. So the pigment is kind of suspended in the glue.

Senan: Yeah, exactly yeah. And when it dries and goes hard the particles of the pigment are effectively stuck together into a flat sheet and you see the color of whatever the color was in those particles yeah. Yeah. So that's the difference and then very briefly on... we're going to come back to this in detail later but very briefly... the other kind of color which is completely different is something called nanoscale color. It's really interesting and it's got nothing to do with energy gaps and electrons. It's really cool way of doing colors. But anyway that's kind of the basics.

Joe: Okay. And so we'll be looking at the different various different colors obviously throughout this program today but um I suppose ethically I'd like to kinda get your thoughts on Mummy Brown.

Senan: Mummy Brown. Mummy Brown is not another name for Mrs. Brown on telly. So uh its exactly what it sounds like. It was a popular color with artists for hundreds of years. And they didn't actually understand where it was coming from because it wasn't called Mummy Brown back then. Um, but the the people who were producing this color, they were secretly grinding up the corpses of Egyptian mummies into dust.

Joe: But like now just okay let's just take a step back for a second. Was this like the purpose was to make the color or was there some sort of significant...

Senan: Oh yeah purpose was to make the color because somebody somewhere along the way discovered that if you ground up a mummy into dust the resulting stuff was a very interesting color that could be used in painting for brown.

Joe: But it wasn't like, so it didn't imbue the your wall or painting with magical spiritual properties or...

Senan: No but I mean the painters didn't know this was the source of it. Yeah. You know. So it was it was just uh the these unscrupulous, we would certainly call them by modern ethical standards unscrupulous dealers were literally raiding Egyptian burial sites for for mummies.

Joe: It's not really the first thing you would think of though if you're looking at a mummy and kind of "You know what I'll do? I'm going to grind that down to make paint."

Senan: Yeah I'd love to know how the first one was was developed yeah. Maybe there was already a powdered up crushed mummy that somebody discovered and they accidentally mixed the dust with water or something I don't know.

Joe: Yeah. It's just strange that they they realized they had a commodity. You know what I mean. Like you might be experimenting with these things and go "Ooh look I can make brown goo from this" but to go...

Senan: "Yeah I really need brown... I'm really looking for... I just can't get brown. My brown paint just isn't doing it for me." Yeah that was probably it. Some accidental conversation in a pub between an artist and one of the guys who was handling mummies probably resulted in the idea. But anyway, when the artists of course found out eventually what the source of this was it was a bit of an ethical dilemma for them you know. They're using human body parts ground up uh as a paint. Um, and actually there was one artist in Britain called Edward Burne-Jones. He was so horrified when he found out this he held a funeral in his garden for the leftover Mummy Brown paint that he had in a tube.

Joe: And was there ever any repercussions for these like the the dealers of mummies or whoever the like these producers of or was it just the art the stuff used?

Senan: Yeah I don't know I think probably it was a bit of a Wild West scenario back in the day so who knows whether there was repercussions or not they probably talked their way out of it.

Joe: It kind of goes straight to though like the extreme. Like grinding up various things you could probably find questionable things to grind up to make into paint but like to go to like a mummy is right...

Senan: Yeah. I mean apart from the ethical issues of of it the fact that they're human remains, you're also destroying valuable archaeological remains from an ancient civilization that was very advanced. Yes. You know so there's all kinds of issues there. But yeah I mean they've done modern kind of X-ray analysis on the paint used in some of the old paintings and have confirmed that there is human DNA in there so yeah. It looks like it's not an old wife's tale.

Joe: So that's really a case of you really have to separate the artist from the art there.

Senan: You certainly do. So as one wag described it it's like people painting with people. Of course it's a bit of an ethical dilemma for museums now because they have these beautiful old paintings and you know how do they handle them they're kind of human grave sites in a way.

Joe: I would imagine though they like throughout the years people must have experimented painting with blood and stuff would think...

Senan: Yeah it's all right if you're using your own blood. Yeah. Of course back in the day there was no shortage of blood running in the streets people knocking off each other's heads.

Senan: So anyway moving quickly along we're going to talk about... Arsenic and old green.

Joe: Right. That sounds poisonous.

Senan: So yeah, the Victorians, you know people who lived like I guess maybe roughly 120 years ago or so, uh, they loved these vibrant green colors that um they named with exciting names like Scheele's Green and Paris Green and so on. Um, and uh they were actually these colors were made from a mixture of copper and arsenic which are both metals and um the arsenic of course we now know is highly toxic but at the time they didn't have an appreciation that arsenic was toxic. Um, and they used it on lots of things around the house, you know? I mean it was slowly poisoning people because it was on their furniture and it was, you know, um, could have been on the presses they were putting their dinner plates into etc. And uh the worst case of all was wallpaper. Um, because there was wallpaper that included this uh toxic green color and if it got damp and moldy, and of course in those days they didn't their housing wasn't as good as ours is now so the wallpaper was almost guaranteed to get damp and moldy at some point. Um, the mold used to metabolize the arsenic and release it as vapor into the air. So people were actually breathing poison air. And I mean like any toxic substance, you know, getting it on your skin is one thing but getting it inside your lungs is a totally different kettle of fish.

Joe: You know, I just I have never liked wallpaper.

Senan: Yeah it's kind of gone out of fashion all right yeah especially those really dizzy patterns. You know you'd I remember when I was a young fella at home um back in the 80s um you know my parents had uh dizzy wallpaper patterns on the wall and you'd come wake up in the morning after a night of drinking and it was the last thing you wanted to see when your eyes were struggling to open.

Senan: Now here's an interesting here's an interesting little fact about these greens. There's a theory that Napoleon died from arsenic poisoning from wallpaper because um they've done some analysis of his body as is uh still available.

Joe: I love the way you just said it's still available. You want like if you wanted like if you could just go home...

Senan: Yeah yeah. You can buy it for 5.99 hurry now. Anyway they found arsenic in his hair. And apparently um there is a story that the whatever room he was sleeping in apparently had green wallpaper so uh yeah it could well have done him in. And of course museums now have the problem of they have these old artifacts with this green paint on them and what do they how do they handle them you know without poisoning all the staff in the museum so it's a it's a bit of a problem.

Joe: I imagine probably the rich richer folk would probably have the nicer paint back in the day.

Senan: The Emperor's New Purple Snails, ha. So yeah there was this is going back like I guess maybe to the Roman era or that back in the middle ages anyway. Um there was this color called uh Tyrian Royal Purple. Um, reputed to be worth more than gold or silver. Um, and uh there were certain um civilizations where it was the law that only royalty could wear this color. And if any commoner was found wearing it there were it was a death sentence. They were effectively trying to jump up and masquerade as royalty by wearing this color.

Joe: Unless they were just really good at pretending to be royalty. Like. "Why are you wearing purple?" "Because I am the emperor's brother."

Senan: The emperor's long lost brother nobody's ever heard of. So yeah I mean how they produced this stuff is a bit of a sticky story. Um, there was a a specific species of Mediterranean sea snail. So there are snails that live in the sea just like there are snails that live on land. Um, and uh this particular species their mucus could be processed in a way that produced this purple color. But like each individual snail produced the minutest amount of it. So they needed thousands of these snails for one gram to get end up with one gram of this uh dye. Uh so that's why it was considered to be incredibly expensive. I mean can you imagine the amount of time it would take to collect these thousands of sea snails. They weren't even on land you had to go into the sea.

Joe: But this is somebody's job. Go and get the snails from the sea and then...

Senan: And it only gets worse from there because they had to be fermented afterwards. So you had these huge vats of thousands of snails being fermented. Rotted basically. Um, the smell was reputedly awful to the point where laws were brought in that it was illegal to have one of these dye uh processing plants within five miles of the nearest town. Right. Um, and eventually um, you know, they had to distill the goo that came out of these fermenting snails until you got literally yeah one gram of the stuff out of a thousand so they were probably boiling it or drying it in the sun or god knows what.

Joe: So I imagine by the time it actually got to color stuff it mightn't just have been quite as pungent one would imagine.

Senan: Hopefully his majesty wasn't there wasn't a whiff following him around everywhere he went.

Joe: Maybe to convince him that that was like the haute couture like fragrance of the year like everybody should smell like this.

Senan: Yeah maybe there's no accounting for fashion tastes is there. But anyway um, so modern scientists have managed to synthesize the chemical structure of that dye. I mean ethically nobody uses snails to make it anymore. And it was actually more reddish more like it was always portrayed in paintings and stuff as as quite a deep purple but it seems now that we've actually managed to make it um using modern methods it's actually more of a reddish purple. And chemically it's quite similar to the dye that's used for indigo jeans. So it's interesting the emperor was swanning around in jeans.

Joe: So it was only used for clothes? I don't know maybe it was used for carpets or materials like yeah well it's a dye so it would only have been useful for certain materials yeah yeah.

Senan: Yeah well it's a dye so it would only have been useful for certain materials yeah yeah.

Joe: Again how. How did they Like I mean you can understand them picking up a snail and flinging it against something and go "Ooh that's a lovely color" when it squished. And you kind of go "oh let's squish loads of snails". But to go "Okay let's harvest them and then ferment them".

Senan: Yeah because I I would imagine if you picked up one of these snails alive chances are it wasn't purple at all. I mean the amount of processing they had to do to get the color was like serious. So like who how they discovered it is beyond me.

Senan: But like as I was saying like pretty much all colors it was organically sourced from some kind of plant or animal or whatever. Um, and that had its uh drawbacks in that uh it was apart from the amount of processing you had to find rare materials you need to do a lot of processing on them and consistency between different batches would have been a huge problem where the color would have been a slightly different shade between different batches. So that kind of stuff. So, like, uh, that's and it was only really in the 1850s that we moved away from those organically based colors into synthetically produced colors which could be done cheaper, easier, there was a definite recipe for them and um, you know, uh, they it opened up a whole new world of uh producing colors once people figured out how to do the chemistry of synthetically creating these colors. And it all arose from a fairly lucrative as it turned out to be mistake in 1856.

Joe: Right.

Senan: Um, so, we this is a medical story. Um, so malaria, um, a long standing treatment for malaria is uh quinine, which ironically is part of the flavor of gin and tonic water. Yes. Um, but anyway uh it's obtained from a pretty rare the bark of a pretty rare tree. So again organically sourced and hard to make hard to find etc. So this uh scientist William Perkin thought he kind of felt maybe coal tar, the tar you get out of coal, um, was uh a similar chemical structure and maybe if he played around with the chemistry of that coal tar he could get this quinine out of it. And instead he got synthetic purple dye. He accidentally created... But the interesting about it of course is that he learned some new chemical techniques and it set him and his fellow chemists thinking and it spawned all kinds of new chemical techniques and there was a a boom in creating synthetic new colors. Um, so colors became cheaper, there was new colors became available that weren't previously available or were very expensive to produce. So it was it was a very interesting um time. And it also um kind of kick-started what we know as the modern chemical industry producing chemicals for all kinds of industrial purposes because those same synthesis techniques that were developed to create dyes and pigments uh also came in handy for processing chemicals in other ways to create other chemicals. So...

Joe: So it all came it came like the pigment and the paint was sort of the precursor to the chemistry.

Senan: Yeah kick-started yeah it got people thinking about the idea that you could make money from learning how to synthetically produce certain chemicals. Yes. And you know that they were unlike the organically sourced stuff they were consistent. It was always the same color or it was always the same chemical that you got out of the end of the process, you know.

Joe: I am never going to his house for gin and tonic. I am never. The gin will be purple.

Senan: Yeah the gin will be purple.

Senan: So while we're on the subject of organic based pigments and the problems associated with them and of course paintings that were done a few hundred years ago, when we go to a museum now to look at them, they aren't really what they used to be. Like they look different not all of them but a lot of them look different now to how they looked years ago. Um, because those organic based pigments that the artists used to uh create their their paints, they change color over time. Um, so the paintings looked different when they were new versus how they look now. Um, and it's a big challenge for like art conservation. You know we don't want to lose these fantastic paintings as as they gradually fade away over time. And what causes it is like if we go back to our our um lecture at the start about uh the energy gaps in electrons and about how those are responsible for what colors we see. Um, you know the the paint on the paintings reacts with things in the air, either pollution in the air or oxygen in the air, and it literally changes the surface of that paint chemically. So now the electron gaps are changing a bit because the structure of the molecules is changing a bit. And and that's one cause of it. Um so you have different energy gaps than what you used to have. And the other one is of course uh UV light. So sunlight includes ultraviolet light which is a very high energy form of light. So when those UV photons impact that paint uh the surface of that paint they impart energy to those molecules which also forces them to change their structure a little bit and again you get different energy gaps in the in the electrons so that it...

Joe: And how how would the energy gaps in the electrons really react to for example Campbell's soup or being flung at them by disgruntled oil protesters.

Senan: I'm sure well, if it's tomato soup that's definitely a problem because tomato soup is acidic. And uh you know um that's definitely going to probably uh definitely probably uh react with the the paint in some shape or form so yeah definitely not good for that.

Joe: Actually reminds me like I mean there are some things like tomatoes for example and beetroot that you would imagine that if you painted something with those natural colors it would just stay like that forever because it just just impossible to get a stain out.

Senan: I know it's typical isn't it the colors we don't want are the ones that we can't get rid of. But actually it's funny you mention something we'll be talking about later on um there was an ancient color produced by the Maya civilization um that has proved to be incredibly durable, one of the most durable colors ever. But we'll come back to that later.

Senan: So while we're on the subject of that to give you an example the famous painting Turner, he liked his sunny scenes. And he used um a color called Chrome Yellow because it had a certain warmth to it and he liked that warmth in his sunny scenes. And um now Turner's paintings have darkened quite a lot because that Chrome Yellow is particularly susceptible to changing color by over time.

Joe: And I imagine it must be kind of a bit of a dilemma. Do you restore them to their former glory or do you let them fade indefinitely to...

Senan: Yeah I suppose I suppose it's a decision isn't it for the individual conservatories but um like I know what there has been some um analysis spectroscopy analysis done on the paints to determine what exactly the original color did look like. And um they have what they some of the galleries have done is they have created digital copies with the colors changed digitally to let us see what those paintings looked like originally. I suppose some places do try and reverse that process if they can. Uh some places may decide that uh it's better to leave the painting age naturally so I guess it's down to the decisions locally made in each place you know.

Joe: No I it must be I can imagine it's a very animated discussion among conservators all over the place. And um so other yellow colors that were important in the history of paint?

Senan: Well there's there's the the infamous Indian Yellow from a very smelly source.

Joe: Can I guess? No I don't want to guess. Go on.

Senan: So um cattle. Herds of cattle were kept and only allowed to eat mango leaves. They were deliberately restricted to a diet of mango leaves. Which wasn't very good for them because...

Joe: And where was where was this?

Senan: I'm not sure. I mean it might have been India because called Indian Yellow but I'm not certain. Now interestingly the cow was a revered animal in modern India now sacred animal so whether it was India or not I I ain't too sure to be honest. But um yeah some people that produced this color used to keep these herds of cows feed them only mango leaves. The cows were kind of undernourished as a result because they were not getting the range of nutrients they need. But the whatever way their system metabolized the mango leaves their pee was very yellow. So they used to these people used to collect the pee from the cattle. Imagine if that was your job. Yeah. And then they would concentrate it which I'd imagine either involved boiling it or drying it in the sun or something until eventually it reduced down into a kind of a paste that was a lovely warm yellow color. And it was really popular pigment with the 19th century artists.

Joe: So it's like asparagus. Does asparagus do that?

Senan: Is it? Oh yeah you're right actually now you mention it yeah yeah.

Joe: And they were selling... so they were this these were artists all over the place. It wasn't just a kind of a I have a farm and I happen to be a painter as well.

Senan: No apparently well word got around that here was this yellow that was nice to use and demand went upwards so more than one place was producing it. However there is now a school of thought that says it might be a bit of an old wives tale. Because um they've done some analysis on uh some of these old paintings with modern you know spectroscopy tools and there is some doubt about whether there's the material came out of cows pee or not. So uh yeah.

Joe: But what are you doing for your PhD? Well let me tell you.

Senan: So we're we're kind of we're going to file that one under maybe or maybe not.

Joe: Okay. Right. We're going to come to personally for me one of the most interesting parts of this discussion...

Senan: I touched on it earlier which is this nanoscale based color. It's really interesting. It's got nothing to do with energy gaps and electrons it's it's really cool.

Joe: We're going to hit the enough with the science button like halfway through this.

Senan: So um this produces color in a completely different way. Um it's a common thing you'll find in insects like butterfly wings, colors on some butterfly wings and so on. And they have really really tiny structures, ridges, grooves, lattices which are referred to as nanoscale because their measurement of them is roughly in the nanometer range. Um so very tiny. But they exactly the gaps the width of these little structures be the ridges grooves lattices whatever exactly match certain wavelengths of light. So they match you know they may have gaps in those ridges that are just the right wavelength for orange or for purple or whatever. Um and uh they can do a variety depending on how those little structures are are arranged and lined up together. They can do a variety of different things. Um so for example um they can enhance or diminish certain colors. So there's a a phenomenon called wave interference. So if you get two waves and you perfectly line up the peaks um they will um amplify each other right? Whereas if you get two waves and you line up a peak with a trough you know from one wave to the other they will cancel each other out. So you the result is these nanoscale structures can alter the wavelengths of the light before it gets reflected to make certain colors brighter or certain colors dimmer than was in the incoming light in the first place.

Joe: But essentially like on a kind of nano level are those kind of are those lattices and tiny little ridges and things. Ridges. Like are we all not made of them? No.

Senan: No. I mean not our although yes we are made of tiny little things on that scale they're not arranged their structure is not arranged in a way that can affect light. Like these have a highly organized structure that produces that color. And it has clearly evolved over time because it is an advantage to them from an evolution point of view you know. But yeah our like our modern scientific techniques are starting to be able to manipulate materials down at that level you know to create structures that are that kind of size. So there are some experiments taking place to try and create colors uh artificially that way using artificial materials as well.

Joe: So essentially you would have something that has no intrinsic color but just reflects light in a certain way.

Senan: Yeah or reflects or scatters or bends or whatever light in a certain way. And the bonus is they can make what's known as iridescent colors. So what I mean by that is imagine one of these colorful butterflies was just sitting on a table in front of you. When you walked around the table and as you were looking at his wings you notice the color seem to shimmer a bit or change as you were moving around. What what's going on there at the nanoscale level is that it is the these little structures are reflecting some wavelengths in one direction and other wavelengths in a different direction. So as the angle between your eyes and the butterfly's wings change as you're walking around the table you're moving from one set of reflected wavelengths into a different set of reflected wavelengths.

Joe: And like most technology I assume there's probably some military purpose for this. Like invisible tanks or bend light around them and all that sort of stuff.

Senan: Yeah potentially potentially. Anyway... we're going to move quickly along to something completely different. Radioactive naivety.

Joe: The naivety I get.

Senan: So um back in the day um when radioactivity was not understood properly and certainly the dangers of it weren't understood um they were actually using radioactive elements. Uh so certain there are certain elements in the periodic table that because of their chemical structure they they release radiation which is harmful to most living things. Um and uh one example is Uranium oxide. So Uranium is a fuel that's used to make uh you know nuclear reactors and it's also used in bombs and so on. But uh this was produced a lovely orange red glaze on on crockery.

Joe: Just I just don't think I think colors are as important as some other people like I really need that orange. You know it's Uranium. Yeah. But look at it. Just look at it it's beautiful.

Senan: So yeah I mean and as awful as it sounds right okay if you handled that Uranium oxide briefly you know that that crockery with that that orange red color on it um you probably wouldn't like the amount of radiation you would take in would be low enough. Um but if you were using it every day to eat your dinner off that's a different matter. Um because you're taking a small bit every day and especially if you're talking about acidic food we mentioned tomatoes earlier on um that acidic food would have lifted some of the Uranium out of the glaze and into your food and you know it's one thing as I said before it's one thing having a radioactive substance on your skin it's another thing having it inside your body. Um so yeah that was one case. But an even worse one was um uh radium and zinc sulfide which was used to make glow in the dark clocks. You know the little the glowing numbers and the glowing hands on clocks and watches. Also used for things like um radi glow in the dark toys for kids to play with etc. Uh and like again naivety people didn't understand that radium was a dangerous substance. And um there were there's uh a group of people known as the Radium Girls who used to work in the factories. Like this was big business there was lots of factories producing this stuff. And they used to work in the factories that made these goods and some of them you know a lot of them died a lot of them got very sick. Um you know sometimes some people it was their job to paint it on um onto either little dots on a watch face or uh onto toys or whatever and you know they might be licking the paint brush to you know suddenly they've got this stuff inside their system. And some of them would you believe even as a a you know if they were going to a party or for a joke they painted it on their teeth or on their nails so their teeth or their nails would be glowing.

Joe: And when is this? Like when are we talking? Is this 19? 20s? Zeroes?

Senan: We're talking about the 20th century mostly. It went on until like it was probably all finished up by the by 1970 if everybody had woken up to the danger and and it uh you know there was no more of it after that. But um it was a serious thing I mean there was an awful lot of people badly injured.

Joe: And relative new I would imagine. Like I mean what where are we talk there 70s 80s 90s zeros?

Senan: Yeah and of course now the antiques industry is dealing with these things. Um you know very few people actually have it in their home anymore. And you know if there's like a clock sitting on the mantelpiece in your sitting room and it has a few dots of radium on it the amount of radiation you're going to absorb off that is little enough. But it's different if you're handling the stuff every day because you work in the factory. Um but yeah it nevertheless you'll see some antiques dealers using Geiger counters just to check if certain things have the stuff on them you know. Because they don't want to be handling it too often.

Joe: I'm not sure I want to buy anything that I need a Geiger counter to check.

Senan: So we're coming towards the end but I suppose we should talk about the future of color. So as we've covered in uh exhaustive detailed here today you know making a lot of these pigments and dyes involves nasty chemicals heavy metals basically things nobody really wants to be around or to have to have contact with. And indeed if these colors are later degrading in the environment we don't want those those constituents to getting into the environment and causing pollution and so on. So there are new techniques being researched for um more environmentally friendly production of of dyes and pigments that don't involve all these dangerous chemicals and and metals. And some of it revolves around organic based stuff it's interesting we've kind of come full circle we went from organic based colors to synthetic colors and now back around organic stuff again because we're we're experimenting with bacteria and algae and fungi to see will they make the colors for us. So we can genetically modify now some of these little creatures so that they will take some uh input material something that's natural in the environment and they will process it in some way and essentially their poo will be a new color.

Joe: So we're going to be using poo. Essentially painting with poo.

Senan: Yeah but like all poo it's biodegradable so you know good for the environment ultimately.

Joe: I imagine there's probably a YouTube channel I bet you I'd be very surprised if there wasn't a YouTube channel painting with poo. Like I'd I guarantee somewhere somewhere out there when asked when did they actually get canceled on their podcast that was the point that was the point that it happened. And so we're going back to organics after like kind of traveling. Why can't we just make everything the color we want it rather than having to paint it. That's just like from a personal perspective.

Senan: That would be lovely. I mean it just means we instead of painting on the pigments they have to go in when it's manufactured but the thing is a lot of these colors fade which is why people want to paint them to renew the color.

Joe: So if they could fix that, if they could fix, if we could just get non-fading paint we would never have to paint again and the world would be a better place.

Senan: So that's our colorful discussion for today.

Joe: Absolutely I uh that's enough with the science and uh we hope you will come back and listen to us soon it's goodbye from me.

Senan: Yeah and it's goodbye from me Senan see you next week.