The hunt for the blackest black | Stories in Colour Podcast S2 Ep7 | National Gallery

When Crow was white, he decided the sun was too white. He decided it glared much too whitely. He decided to attack it and defeat it. He got his strength flush and in full glitter. He clawed and fluffed his rage up. He aimed his beak direct at the sun's centre. He laughed At his battle cry, trees grew suddenly old. Shadows flattened. But the sun brightened. It brightened and Crow returned charred black. He opened his mouth but what came out was charred black. Up there, he managed. Where white is black and black is white, I won. That is Ted Hughes' Crowfall. Welcome to Stories in Colour, a podcast from the National Gallery searching for histories of how colour has changed the world. Today we're on a hunt with artists through time for the blackest black, the deepest black, the most accurate blacks, the most atmospheric black pigments. I'm Bex Leary from the Digital Department here at the National Gallery and with me today is our guest Stuart Semple. Stuart is a multidisciplinary British artist whose work spans painting, performance, internet art and installation. His work is known for its vibrant use of colour and innovative techniques that challenge societal norms and question the role of the artist. Welcome to the podcast. Hi, good to be here. Yeah, thank you so much for being here with us. As I've introduced, we're on the topic of black and specifically black pigments today but we probably need to start with what black is and I've got a Pierre-Auguste Renoir, French artist, who said I've been 40 years discovering that the queen of all colours was black. He also said nature knows only colours, white and black are not colours. Is black a colour? Okay, it's a bit of a murky subject isn't it because actually it's kind of the absence of colour, at least sort of scientifically, but you and me definitely see something and point at it and say that is black and I think we relate to it like we relate to colours. I agree, yeah. So it probably is. There's like a visual sensation of seeing black and there's black on an artist's palette. Common sense says to us that it's a colour, doesn't it? Yes, yeah. But yeah, I guess strictly speaking scientifically it gets categorised as achromatic, so like a colour without a hue. So grey and white would be in that category as well. Yeah, I mean that makes total sense. Yeah. We'll go back in time to look at how far back have humans used black paint. Yeah, interesting. And it's far, isn't it? It goes right back. It goes all the way back. I mean it kind of starts when we start cooking things and heating things. Making fire. We're making fire and we're preparing food and this is kind of how charcoal comes to exist really. But there's almost something mystical and magical about the material because of course it's giving us life, we're eating this food, it's giving us warmth. So when we sort of excavate really early civilisations we're finding charcoal in all of these places and it's not long after we start drawing with it. Yeah, so charcoal being kind of organic matter that's been burned up in a fire. Yeah, but not just burned, burned in a very specific way. So it's burned without oxygen around it, so it doesn't just burn into flames. It doesn't burn out, yeah. No, we want to oxidise it and take out some of these sort of other particles to leave the charcoal. That's when it's useful. Yeah. I love that kind of early association between like the darkness of the charcoal but the light of the fire. Yeah. And that kind of contrasts that this very early pigment material for art comes kind of out of light. Yeah and you want to think of like early cave drawings are really interesting and obviously the caves would have been dark so there would have been fire present when they were drawing on them. Yeah. So this play of light and dark and shade and shadow is really powerful. Yeah, totally. I'm thinking of the Lesceaux caves in the southwest of France in the Dordogne. Maybe we should describe them. There's all of these animals, aren't they, on the walls of the caves. I think when we talk about the caves, I think there's about 600 different images in the caves. So there's not just animals, there's like hand prints, there's sort of abstract forms and they're really fascinating because they were sort of discovered by four teenagers roaming around with their dog. The story is the dog runs in a hole and they don't know where it is and then they sort of go and realise there are these caves. They come back later with some lambs. Can you imagine being a teenager and just uncovering this sort of treasure trove? Amazing. Incredible. I think they maybe started like selling tickets to go into the caves. I heard that. I don't know if that's true. It wouldn't surprise me. I don't know if that's just a story but obviously eventually there was an archaeologist who, you know, verified that they were actually Paleolithic drawings. I think they were something like 17,000 years old, those drawings, they reckon. It's crazy. Absolutely amazing. Yeah, discovered in September 1940. Which is my birthday. September the 12th they were discovered, which is why I remember it. Not 1940, I'm a bit younger. That's so nice. That's a really cool thing to share a birthday with. I'd never forget the date they found it. I don't think you can visit them today because, yeah, concerns around the light and the preservation of them. I think they locked them down in the 60s but they've made a replica so you can still go up there and see something. Maybe we should say there's, so it's not just lion drawings and charcoal, there's also red earth pigments, brown earth pigments as well. The ones that I remember most are the ones with the cattle with the big horns. Yeah, the sort of hunting scene. Yeah, they're very animate and these are like original outlines, drawings and I think that this is like an artist's artifice that we kind of don't really think about as being an artifice. Like the idea of doing an outline of something to create a drawing. But obviously we're not outlined in real life, are we? No, and I remember my art teachers used to really get at me for outlining everything and of course we draw as kids, don't we, like cartoons and the outline is everything but the real world isn't outlined. No. Yeah, it's interesting how artists have done that through history, I guess. Like you think of Leonardo da Vinci and all his drawings or even getting later into more modern art with Degas and the kind of blackout lines that impressionists start using. I mean Degas is almost a cartoon sometimes, those drawings, isn't it? Yeah. But he does something really interesting with his line. It's not just an outline, there's sort of emotion in it, there's variance in it and then when he uses soft pastels with it, he can blend that black line and then we start to get more of a flow in it. So, it's quite interesting. And interesting that it is typically black, I think. Yeah. That artists are using as outlines. I wonder if there's something that we feel is neutral about the colour in that sense because it's achromatic. I don't know or maybe it's the strength of it. I don't know, what do you think? Yeah, it's kind of the finiteness of a line between this is fantasy, this is reality, this is the object, this is the rest of the world. We'll draw a hard, fast line of nothingness between the two things, maybe. Something like that. Yeah, I like that. We've talked a bit about charcoal. We should say that's a kind of carbon black. So, not carbon in the sense of diamonds but carbon in the sense of it burned. Yeah, it's carbonized. Carbonized. Maybe we just look at a few examples of things that were burned through history for artists to use as pigments. So, bone black. Of course. Quite an obvious one. Don't really need to explain how that gets made. Ivory black. Of course. Charred ivory. One that obviously we wouldn't want to be doing. Thank goodness we're not doing that anymore. Today. Lamp black. I feel like this is the one that's less obvious. Is it? Soot. Yeah, but it's not the lamp that's burned. No, okay. We're not burning lamps. But the soot, yeah. But we are using the soot. Yeah. And it gets added to like gum and water and you can get an ink out of it. I love this one. This one is so specific. Peach stone black. Yeah, I love that. I haven't heard of that before. So, what are we doing? Just burning a load of peach stones. Just charring a load of peach stones. That was one of the most popular ones. I wonder how different it looks from some of these other ones or whether they all look pretty similar. There's descriptions of how artists were choosing them for their different qualities. Charcoal is a bit bluer in tone. Okay. Bone black is a bit more saturated. Lamp black's like, you can kind of imagine from the soot is very fine. Like the particles are really fine in that. So, it handles quite differently, I think. The final one example I had was vine black. It was apparently a really favoured source for oil paints. So, yeah, artists, I guess, were aware of these differences between carbon blacks. But let's look at an example of somebody who was very expert in black fabrics. The artist Franz Haus. Yes, okay. One of his most famous works, The Laughing Cavalier. Of course. He does look quite cavalier, doesn't he? He looks cavalier and he looks extremely happy, doesn't he? He's very joyful. Very joyful. He's got a real turned up little moustache, brown moustache. Rosy red cheeks. Very rosy. And of course, this black hat is the thing, isn't it? Extravagant black hat. Yeah, massive floppy thing. We've got a plain grey background behind the portrait. It's sort of a portrait from the waist up. He's wearing a white ruff, lace ruff. On a very ornate garment, isn't it? It's got everything, all sorts of colours and embroidery and it's very opulent. Neutral colours, I think you would probably describe them as, say, browns and white. The black is so varied to create that sash around him, isn't it? I think Van Gogh said Franz Haus must have had 27 blacks. I bet he was jealous. He was always desperate for paint, wasn't he? Well, I think that the sash is coming to life because it's got a lot of personality. It's got real flow and form to it and that's being brought out by the different tonality in all these blacks. And that's giving it a real sense of not just form but movement, isn't it? And it's intersecting the sort of bottom third of the painting. And it's interesting because your eye initially goes to the hat and its relationship with the grey background, but it's actually where you linger tends to be on that sash. I would encourage people, we've got lots of Franz Haus in our collection, just not quite as famous an example as this one, which is why we chose this one to look at. But go and walk around the collection and look at how artists are depicting black fabrics, because I think we think of it as monochrome, right? We think of it as this kind of singular thing. It's amazing how fabrics... And also, we don't consider how light plays on black. Right. You know, as it folds, as it casts a shadow, that there is depth and sort of nuance in black. Yeah, absolutely. And there's one point where it becomes grey and there's another point where it becomes pitch black. But in between that, there's a lot going on. And you see that in drapery and well-painted fabrics. Especially, I guess, fabrics like satin that capture the light or velvet that captures it in a very particular way. Yeah. Dream for artists to paint. And it's really fun painting that stuff. Yeah. I think this is a really good point for us to have a quick break. Okay. So yeah, we'll be back after the break to talk about somebody whose hero was Franz Haus. See you after the break. Welcome back from the break. We're looking at an artist whose hero was Franz Haus, who is John Singer Sargent. Could you tell us a little bit about how he was famous for using... Well, I mean, I think one of the best examples is his Madame X painting Portrait of Madame X, isn't it? In which we see a very elegant black dress painted, actually. And interestingly, the way he outlines, if you think of the painting of her, her face is almost in profile and it's almost got a black outline around the edge. And he really relied on black a lot. You can see in that painting, he needs it. If you took the black away from him, he would probably completely and utterly freak out. He wouldn't know what to do. Yeah. There's so much synergy here, isn't there, in how the draping of her dress, comparing to Franz Haus, we can compare how the light is capturing on the folds of how it hangs around her waist, how it's darker on the bodice. We're seeing this contrast. The black's used as a contrasting element, which draws the attention to the skin tone, actually, in this one. And a lot of artists use black like that to draw our attention almost away from it. But it's interesting how Sargent uses it here, because we've almost got this love heart across her chest, haven't we? Which is almost a void black. Because her skin is very pale. It is very pale. It's that contrast that's really powerful in this one, I think. And she looks very fashionable to me now. Would she have looked very fashionable at the time? I don't know, but it is sort of the epitome of elegance, isn't it? This sort of chic, black dress. It's very refined. It's very elegant, very sophisticated. Very sophisticated. And this was painted using bone black, actually, that we talked about before, as well as other pigments like earth colours. We have a Sargent, actually, in the Gallery's collection, Lord Ribble Stale, who's also wearing black. So, yeah, an artist definitely very refined on black. Oh, he was really into it. There's actually a story about Sargent and Monet, Claude Monet, the French impressionist. Sargent couldn't believe that Monet didn't have a single black pigment on his palette. And I guess, yeah, when we think about Monet, that contrast of an artist that, you know, you don't think of black at all. I don't know. I think it's interesting that an artist can kind of be, not defined by, but really captured by a colour like black, and Sargent so clearly was. Yeah, the impressionists are more linked to chromatic blacks. Yeah, I think that's the point. So I think when Sargent goes over to see Monet, I mean, Sargent's obsessed with impressionists. I mean, he's a huge fan. So I think when he goes to meet Monet, it's like seeing one of his idols, you know, so he's, you know, being as though he's so reliant on black, seeing like none on his palette at all. And of course, when we talk about chromatic blacks, maybe we should explain kind of what the idea is in that, that, you know, using pure black straight out of the tube doesn't really have the subtlety and nuance that maybe we want as artists. So if we start mixing together contrasting colours from other ends of the colour wheel, I'm getting a bit geeky. Complementary colours these, aren't they? Yeah, if we start bringing the complementary colours together that from the other ends of the colour wheel, they sort of cancel each other out. And they make blacks that we can control a little bit more. So we can make them a bit warmer, a bit cooler, and they've got a bit more nuance in the surface. Because actually, if you get real pure black, say carbon black on your brush, it can make the whole painting very, very muddy. And that's why at school, we were probably told, at least I was, don't use black, put it away, because it can just take over everything. So mixing these chromatic blacks really helps us. But let's not forget, Monet didn't exactly do that. He would use a lot of colours in his shadows. You know, we see purples in the shadows and blues and things. And the Impressionists played that trick a lot. Definitely those, yeah, colourful shadows. I think that's quite a common story. Actually, we hear from artists that at art school, they are taught, don't use black from the tube. Yeah, yeah. You get in a lot of trouble for that. Make your own black, like proper artists. To go back to Madame X and black dresses. Originally, in kind of Western cultures, black would be very much associated with mourning. Exactly, yeah. And sadness. And it wasn't, yeah, really until the late 19th century. And you start getting people like Madame X wearing black very fashionably that kind of, it was freed from this just being about mourning and became about kind of chicness. So I guess the most famous example of that would be Coco Chanel's Little Black Dress from the 1920s. Absolutely, yeah. Hepburn, Audrey Hepburn in Breakfast at Tiffany's in the 60s. I was thinking about why black is seen as like a very flattering colour. And I think it is because of how it absorbs light. Yes, it definitely absorbs light and it changes the silhouette. Yes. But it does draw attention but in a sort of subtle way. And you can see how maybe we moved from a process of wearing it in mourning and reverence from something sombre. It sort of kept that understatedness, that respectableness and then sort of morphs into something that may be seen as elegant. It kind of contours the figure, I guess. It does. And creates, the texture kind of becomes less visible. Even when it's velvet or satin, I think you do get the light playing with it. But the texture of what you're wearing becomes less visible, I think. We're going to talk a bit more about how light interplays with black or is absorbed by black. Yeah, that's really important, isn't it? Otherwise we're not going to understand what it is. We're going to go, we've gone really early in human history. We're going to go right back to the start now. Oh, the start, start. The start, start. Well, none of us knows what the start was. We can have a go. We can have a go. Christians, of course, believing that God created the heaven and earth and those famous opening lines of Genesis. Lots of Near Eastern mythologies, in fact, many mythologies from all across the globe, start with a void. Blackness, darkness. Yeah. I think that is so interesting that there is this kind of very human idea that it all starts in total darkness. Pitch black, the way you described it. Described, I think, a colour that would come to mind. Yeah, so before the light, what is the absence of light? What is the absence of light? The only thing we can picture is probably black vastness. I'm going to read the start of Genesis, actually, because I think these are such famous verses and have been so impactful. This is the King James Version. Apparently that word for darkness in Hebrew is a really guttural word. It's really almost dissonant. A sense of a kind of primordial gloom at the start of the world. I think in the sort of ancient Hebrew, it's like the absence of everything. They talk about this Ein Sof, the something that has nothing. And then there's this divine spark inside it that starts to radiate. One of the first depictions of this that I know about, an artist trying to capture the void, was Robert Flood. He does this in 1617. We're going back quite a few hundred years now. He does this. It's almost like a very early piece of abstract art when you look at it. It's like a black square, just etched ink, where he's done almost like cross-hatching to create a totally black square. He surrounds it on all four sides of the square with the inscription in Latin, et sic in infinitum, and so on to infinity. Wow. Way ahead of his time. So ahead of his time. I had no idea. That's cool, isn't it? Yeah. I didn't think we got there till the 1900s, but that's incredible. Yeah. I feel like that's kind of the original black square. I mean, he's not an artist. He's trying to kind of almost scientifically convey what he felt the darkest of dark, imaginable beginnings of the world are. And he drew on both Egyptian, Greek creation myth and the Genesis passage that we just read. An Englishman kind of almost doing proto-abstract art in the early 17th century. Kind of cool. We're taking a break. So yeah, afterwards, we're going to get into the real search, as we said at the beginning, for the blackest black. And we're going to dive into more scientific applications of how black has been used and created almost. So we're on the hunt for the blackest black, but we should probably touch more scientifically now. We asked whether black was a colour. Yes. At the start. But what does that really mean in terms of scientifically, what is black? Yeah. What's actually going on? Exactly. Well, what's going on when you perceive any colour is light is bouncing off an object, it's going into your eyes and you're perceiving it. There's all sorts of weird stuff going on with linguistics and our neurology, but we won't go into that. So a red thing bounces red light at you and you go, oh, that thing's red. A black body, a black thing, is actually not bouncing light back to your eyes at all. It's almost absorbing it. We perceive that as black. It's almost the absence of light. And it all kind of starts when Isaac Newton gets a prism, like a bit of glass. You think of that Pink Floyd album cover for Dark Side of the Moon. White light goes in one side. On the other side, we see a spread, which we call the spectrum. We see all these different colours that make up white. But Isaac Newton obviously realises there's no black there. So where is it? What's going on? What's this missing thing? And scientists are fascinated by that, of course. So a true black would reflect no light at all because all of the photons are absorbed. And so, yeah, most of the blacks we see, there's some reflected back and perceived by the human eye. Absolutely. And like carbon blacks even, they've got a sheen to them. They are reflecting some light. So, yeah, the ultimate black hole, if you like, in space sucks all the light into it. 100% of light. Yeah. Nothing's getting back. And that makes it quite a hard thing, I guess, for manufacturers to reproduce, especially for artists to reproduce that idea of total blackness. But people have been really trying, haven't they? People have been really, really trying. So the first sort of example we saw was a material called Vantablack, which came out in about 2016. And a lab called Surrey Nanosystems created it in a lab, in a vacuum chamber. In Britain, Surrey in Britain. Yes, yes, here in the UK. And what they did was they worked out they could grow these carbon nanotubes on a surface. So to put that in English, if you think of smaller than a white blood cell, that's a nanoparticle, tiny, tiny, tiny, less than a bit of hair, that small. So imagine a forest of those all stood up on their end. When the light goes into it, it bounces around and it can't come back out. It's a trap. It's a light trap. It's a bit like a forest. So they call that Vantablack, Vertically Aligned Nanotube Array, Vanta. And that's what they created. The black is black. And in those days, they wanted to use it in lots of applications for space exploration, inside of telescopes, military uses, things like that. I found this cool quote actually from, I don't know if they got it right, but an American drama series called Fleishman is in Trouble recently talked about Vantablack. Let's fact check them, see if they got it right. Vantablack was lab-created material that was said to be the darkest black in existence. It was created for the military to help hide satellites and jets from detection. And it is so dark that you're not even allowed to use it legally. It is the closest you can get to a physical manifestation of the void. Yeah, that's not quite right. It's not quite right, is it? It's almost right. They've almost got it. So it wasn't made to get rid of satellites. It was actually made to stop stray light in telescopes. Okay, so to make them more accurate. Yeah, so the blacker the inside of a telescope, the further you can see, because there's not stray light. And it's the same for cameras. But there's lots of applications, so they're developing it for lots of stuff. It's not illegal to use it at all. Car companies have used it, deodorant companies, buildings have been sprayed. Wait, deodorant? Yeah, yeah, yeah. How have deodorant companies used it? As like a sort of branding, marketing kind of thing. Oh, fine, I was going to say. The architect Asif Khan, a couple of Olympics ago, did a whole building coated in the stuff. So no, it's not illegal to use it, unless you're an artist. Tell me more. There's only one artist in the world who's allowed to use it, and that's Sir Anish Kapoor, who has the exclusive rights to use it in art. Okay. So everyone else can use it. If you apply to Surrey Nano Systems, they'll coat something in it for you. For any other use. Yes, unless it's art. The minute you tell them you want to make art with it, they won't let you do it. We should say Anish Kapoor, sculptor known for his mirrored cloud gate in Chicago, sometimes called the Chicago Bean. Yeah. Is that right? Closer to home, the Helter Skelter Orbit Tower in London's Olympic Park. But yeah, tell me more about how artists have kind of reacted to this kind of single person being able to use... The art community was quite upset about it because it felt very exclusive to a lot of people. And I think a lot of people couldn't understand it. I mean, it's not a paint. You can't just dip your brush in it and paint away with it. This is a complicated lab process. Yeah. But the fact is, artists are still excluded because they are artists from accessing it when other people can. So it did feel a bit unfair. Was that how Surrey Nano Systems, is that how they justified it? That it was such a kind of complicated material to use that... They, at the time, they justified it in a couple of ways. They said, you can't make much of it and it's hideously expensive. Yeah. They also said that Sir Anish has dedicated his life to exploring pigments and the void and the absence of form. So it's an obvious choice of someone to work with. Right. So that was their approach to that. Yeah. I'm sure there's many other artists who are exploring similar things. Has he been, has he actually been using it? Has Anish Kapoor been using it? Yeah. So we waited almost a decade and then finally Anish unveiled his sculptures that he made. A couple of Venice Biennales ago and he showed a series of objects that he coated in Vantablank. And these are kind of like cubes and spherical objects that appear almost flat because it sucks up so much light, it makes 3D things look almost like a hole in space. It's an amazing visual effect. So he did that and then he's had another show in New York of those as well. So yeah, he's been using it. You've been working on something to give artists more opportunity to use something like the Blackest Black in Vantablank. Could you tell us a bit about that? Well, I've been making paint since I was about eight years old. You've been making paint from scratch? Yeah, since I was a kid. So I've always been making paint, using my own work and my shows. And when Anish got the exclusive rights to the Blackest Black, I released the Pinkest Pink on the internet and I let anyone in the world use it apart from Anish Kapoor. And off the back of that, a lot of people started writing to me saying I had to try and create black as good as his. So I've spent the last eight or nine years of my life trying to make super blacks and I'm now up to version four of my black, which is called Black 4.0. Okay. And it's a really great super black. It absorbs 99.8% of visible light. It comes in a bottle. It is affordable. Hundreds of thousands of artists are using it for great work that wasn't possible before. And it is absolutely a paint. It's very different than Vantablank because Vantablank, interestingly, absorbs a lot more light. Okay. But the light it's absorbing is outside the visual spectrum. Okay. Because our eyes can only see so much. Yeah. And at one end, we've got the infrared and we've got the ultraviolet at the other. Yeah. So my paint focuses on what we can actually see, because as artists, that's what matters. So if you put mine and his in the lab, his is going to win. Yes. But if you look at it with your eyes, they're about the same. That is really interesting. I hadn't realised that about your pigments, that the sensation of seeing them is pretty similar. Yeah. Because we're talking about art and art is measured with eyes. We look at paintings and sculptures. We don't walk around galleries with spectrometers measuring things, do we? Sometimes our scientific department do, I think. To make sure the paintings are protected. But I think they're an exception. I think they're definitely an exception. Hundreds, thousands of artists are using this pigment. What has the reaction been like? People love using it because they haven't had access to anything like that before. And it really is completely different from the other blacks. And I sort of think about art history and I go back to Caravaggio and people like that. And I think, gosh, if they'd have had a black this deep, it would have been really exciting. So people are really getting into it. And there's so much cool stuff being made every day with it that just kind of wasn't possible before. This is a complete side note. But we asked our scientific department about the Caravaggios in our collection because we were thinking of them for this episode. Apparently, they're more like brown. We think of Caravaggio's backgrounds as deep black, but... Well, iron oxide has a very brown undertone, doesn't it? Yeah, so they do have black pigments in them. Because of the way they're mixed, if you look really closely, maybe this is only under a microscope, but... Wow. I don't perceive them like that at all. No, no. The visual sensation of them is complete darkness, isn't it, in the backgrounds? Sorry, let's go back to your pigments. Have you been using them in your work as well? Yeah, I've used them a few times. One of the pieces I made was a sculpture, which was a big black room that you sat in for five minutes in complete darkness. You had no sense of space at all. And then five minutes later, a light would come on so that you could leave. And it was quite meditative. Sort of very inspired by Rothko, actually. Okay. His chapel. His chapel, which is in Texas. You know, these big black field paintings are massive. Yeah. And the fact that it's this sort of transcendental, meditative, takes you into another realm. So I'm really interested in that. And how it makes you feel and what the experience of it is like. In this hunt for the blackest black, scientifically, MIT have made a material that they say absorbs at least 99.995% of incoming light. Have you heard about this one? Yeah. The diamond that's been covered in this blackest black material. It's called the Redemption of Vanity. I do quite like that contrast of a diamond, which is normally so sparkly and the whole thing with a diamond, right, is how much it reflects the light and plays with it and its light and brightness. And yeah, that is quite cool. That idea of almost completely hiding the kind of nature of something. I think it's brilliant. But what's so funny is all these people squabbling for a percentage of a percentage to get, you know, some sort of award for the blackest thing. Because after some point, we just can't tell the difference. On that note, we are done. That's the last bit of the podcast. Actually, we're done with the main part. We do have our question from the audience. So yeah, now it's time for, yeah, we ask our audiences whether they've got any questions for us about the topics that we've been looking at. And one person on YouTube has asked, are there any historical black pigments that are no longer used because either the black pigment was toxic or it's now unavailable slash unethical to use as a paint pigment? Well, I think it's got to be the ivory black, hasn't it? As we said before, thank goodness. Thank goodness that that's no longer in use. I can't actually think of any black pigments that are renowned for being toxic. Maybe there is. Listeners, you can tell us if you can think of any. But yeah, I think ivory black is the best example of one. Okay. Well, that does bring us to the end of today's episode. If the listeners have got any more questions that you want to ask us about the story of colour, you can email us on podcast at nationalgallery.org.uk or you can send us messages on social media. I just mentioned the podcast. And we will try and answer some of those for you in our next series of stories in colour. So thank you so much for joining us this day's episode. And with huge thanks to our guest, Stuart Semple. I have been your host, Bex Leary from the digital department here at the National Gallery. Our producer was Harry Rosehill. Our researcher was Hannah Rogers. Our scientific advisor was Marika Spring. Our technicians were Ian Warren, Tom Gulliver and Timothy Carpenter. Our video producer was Jeanne Kenyon. Thanks for listening.