A designer is a professional who creates visual plans for objects, mainly in a commercial context, for example for chairs, posters, clothes, websites or buildings. I mean graphic designers, interaction designers, fashion designers, industrial designers, interior designers, as well as architects, who design buildings and spaces.

I noticed that many architects and designers wear black regularly. Regularly enough that if I were to look into that person's wardrobe I would be impressed by its blackness. I don't mean wear exclusively black and I don't even mean they wear all black outfits, just mostly black, most of the time.

Not all designers wear black, not even most designers wear black. But a noticeably larger portion of designers wear black than the general population. And they wear it voluntarily: without any obligatory dress code imposed on them. A designer wearing a white t-shirt and blue jeans would be just as acceptable as one wearing all black. Which, despite more relaxed norms, is simply not the case for the politician without suit or the doctor without lab coat. If I look round my design class, which consists of twenty-one design students and one lecturer: five of them are wearing all black outfits, including the lecturer, and four more are wearing a main item of clothing which is black.

Black and white are the only two colour words to appear in every language. They are often used as synonyms for light and dark. But the power of black and white goes far beyond language and socio-cultural associations, it goes right down to our nature as animals. Since we are diurnal animals, metaphors of light and dark are consistent for all of us: we cannot see in the dark so blackness represents danger, the unknown, fear. When it's dark we sleep and when it's light we're awake. Since sleeping is like dying and since darkness means danger, black means death first and foremost. This is true in almost all cultures.

Black has a rich number of meanings but its fundamental associations are negative: evil, night, death, witchcraft. The witch, who is practises black magic, is a black clad character in the Wizard of Oz, in Harry Potter and in Macbeth. In Men in Black, John Harvey calls the witch a nightmare version of the widow, since black means mourning, evil and death.

Black was worn by mourning women in ancient Rome and Greece. Little has changed, black is still the primary colour worn at funerals in virtually every country. Hamlet wears "customary suits of solemn black" which he also calls "suits of woe", because he is in mourning.

The demonstration of sadness is important and Hamlet refers to it, pointing out that someone might play at being in mourning by wearing black as costume. Death can provoke all sorts of unusual reactions in the bereaved, from hysterical laughter to total numbness. To avoid people whispering about strange behaviour black is used as a shorthand for the inner turmoil we can assume is felt.

The first people to wear black professionally were priests, because they were the first professional mourners. The Benedictines served as mourners and were knows as the nigri monachi, the black monks. Black spread to the eastern church too and is worn by Orthodox priest.

It was also worn by the Dominicans, who wore a black cloak over a white undergarment, symbolising the pure soul covered in sin. John Harvey wrote that "to wear the same clothes as other people is to assimilate to the group and to enjoy its strength: any uniform has this effect". This is true for soldiers, for lawyers, and for designers.

Black became associated with christian asceticism, humility, seriousness and penitence. The showing of a white undergarment is also worth noting, black and white seem inseparable in this way. Later on in the 17th century we see the nobility wearing all black with a white frill collar, in the 19th century the standard business suit is black with white collar and cuffs, in the 21st century designers pair black clothes with white sneakers.

In the Middle Ages black was still primarily worn at funerals and by priests. The rest of the middle age world lived vibrant lives, with colourful tights, doublets and two-tone overalls. Then doctors of law and medicine began wearing black as a professional garment. Black adopted a strong advantage thanks to priests, it became serious and it became professional.

Soon black became associated with immeasurable wealth and privilege, for it began to be worn by kings. Philip II, like Hamlet, wore black after his father's murder. He remained in the colour of mourning for the rest of his life and was also, importantly, the high priest of the inquisition. It was also worn by the king's ministers and became, according to Jehan Courtois, "the most popular colour in dress, because of the simplicity which it has".

Indeed, Philip's simplicity of dress meant that he was often mistaken for a common citizen. According to John Harvey black came to symbolise an "ostentatious seriousness" for it was "ostentatious through the show it makes of renouncing ostentation."

The jewish Sumptuary laws of 1416 declared that for Italian Jews only black cloaks were allowed, rich colourful garments could only be worn under the black cloaks. This was to send a message of humility and piousness. Black here was used to say "don't see me, except as you see that I am humble and pious."

Black became so common among the merchants in Venice that a visitor who came to city in 1498 declared that "they all look like Doctors of Law". Black had become the colour of mourners, priests, doctors, merchants and kings. In Russia, Ivan the Terrible wore black and swore his priest warriors, the Oprichniks, to absolute loyalty and forbade them from wearing anything other than black. They even rode black horses.

In the 19th century black became part pf general fashion. In the Victorian age, men wore much more black than they do today. Its previous associations collided to form the basis of a new fashion for the middle classes, which continued to rise in number. Black became the colour of evening clothes, of business, of the city and of society.

Before the 20th century black was mostly worn by men. Black was only worn by women to signify mourning. This changed in 1926 when Coco Chanel published a drawing of a black dress in Vogue magazine. Chanel's little black dress became an icon and was famously worn by Audrey Hepburn in the film Breakfast at Tiffany's.

Black came to represent fashion and style. It is now typical for evening attire and is the main colour worn on the red carpet and at other high-status events. The fashionableness of black is apparent when we say that something "is the new black" to describe the next big thing in fashion. One study showed that the perceived sophistication of a brand is positively affected by the presence of black.

Because of its negation of light, black makes a clothed body appear all silhouette. The eyes cannot focus on blackness and are drawn naturally to the face, which is framed in black. It gives the face a new intensity, which is otherwise lost when colourful clothes are worn.

In interviews I conducted with designers, this focus on form over colour came up several times: Sandra Pfeiffer mentions that her love of black stems from her desire to focus on form, while Sarah Owens believes wearing black makes her "focus on quality, material and cuts". Laurence Hau likes black because it has "timeless form".

In a 2014 study researchers measured white, red and black dresses in terms of sexual receptivity, fashionableness and attractiveness. Black and red both enhanced perceptions of attractiveness, black primarily via perceived stylishness. And black is the most frequently worn colour by women in their profile pictures on dating websites.

In an online colour survey black came out on top as the best colour to wear when trying to impress or woo since it scored highly on perceived traits such as intelligence and sexiness. The respondents considered it the best colour to wear on a first date or to a job interview.

Black clothes are often used to make political statements. Opposing political movements use black to mean entirely different things. In the first half of the 20th century black was used by the Italian fascists. They were known as Blackshirts. While in the 21st century black blocs are formed by left-wing protesters who dress from head to foot in the colour, now a symbol of opposition to fascism, though it was exactly black clothing which was used as a symbol of fascism only decades earlier.

Johnny Cash wore black as a symbol of solidarity for those who suffer under oppression and came to be known as the Man in Black. Black is his "symbol of rebellion - against a stagnant status quo, against our hypocritical houses of God, against people whose minds are closed to others' ideas." In the song titled "Man in Black", Cash explains that he wears "the black for the poor and the beaten down … in mourning for the lives that could have been … so we're reminded of the ones who are held back".

Cash embraced the fundamental negativity of black. He wore it to tell us that everything is not all right in the world and that life is always shadowed by doom and death.

Black still functions as a political symbol of solidarity. Actors wore black gowns at the 2018 Golden Globes as part of the Time's Up campaign. Time's Up was organised by some 300 female directors, agents, actors, executives and writers to fight sexual misconduct in the industry and it was black clothing which was used as a symbol for the sobriety of their message.

Black has often been strongly associated with communism. Massimo Vignelli was a graphic designer and architect who almost always wore black and who had strong socialist leanings. Jun Aoki, a Tokyo architect, wrote that architects wear black because "an architect is (still) a kind of communist".

Laurence Hau radically changed her clothing style after a visit to Hong Kong and an "overdose of capitalism". She felt that by wearing her previous wardrobe which consisted of colourful tops in yellow and royal blue with colourful skirts and a butterfly in her hair she was part of the typical Hong Kong cute look, a style she no longer felt comfortable with. She began truly only wearing black after completing a design internship where the designers always wore black clothes with white sneakers.

Her boss explained that the look allowed them to stand in a neutral position in relation to their work. However, in this case black clothing is less a symbol of neutrality than a symbol of political solidarity with the left. Laurence changed her wardrobe in reaction to the breakneck pace of a fashion industry obsessed with obsolescence.

Designers did not always wear black. As late as the 1960s modernist designers like Vignelli wore, and encouraged everyone in his studio to wear, a plain white lab coat.

During a time of great political upheaval in America, Katherine McCoy, who worked with Vignelli at Unimark, said "we were encouraged to wear white lab coats, perhaps so the messy external environment would not contaminate our surgically clean detachment". The lab coats weren't really practical, instead they were used to impress clients, because they looked like doctors or scientists. And since to adopt the colour of a group is to adopt its strength, these designers were naturally perceived as serious, rational, objective, intelligent and competent. This performance allowed Unimark to win huge clients.

The strong, traditional contrast between black and white is embraced by designers when they wear black with white sneakers or socks or black trousers with a white shirt. Josep Lluis Mateo, a Barcelona architect, refers to this tradition of formal contrast when he calls the two colours “the two extremes”.

Fashion designers are especially well known for wearing black, frequently combined with white. Designers like Tom Ford, Michael Kors, Karl Lagerfeld, Marc Jacobs and Jean Paul Gaultier all wore uniforms of black and white, uniforms from which they virtually never strayed.

Why would fashion designers, known for creating innovative and extravagant garments, themselves choose to wear almost plain black outfits? The reason is because by wearing black they are designating themselves as separate from the models, separate from consumers of fashion and separate from other professionals, they are showing “I am the designer”. Black symbolises their profession and their professionalism.

Vignelli eventually abandoned his suits and white lab coats in favour of an all black wardrobe, even designing black clothing. "Yes, it does make you look like a priest but that's OK, it's a visual program. We were not making fashion which is transitory and based on the idea of obsolescence. We were making clothing with a purpose, to protect and follow the body. We grew tired of being fashion victims”, he said.

Even in their work the Vignellis confined themselves almost exclusively to the use of black and red on white, a reference to colour purity in the modernist tradition. Massimo Vignelli loved black because "it's the best colour, there is not colour that is better than black". For him black had it all: class, practicality, "it works 24 hours a day" and "it's good for everything".

Matilda Kahl, an art director in New York, admits that although she has complete freedom when it comes to her work wardrobe she has adopted a daily uniform of black trousers and a white shirt. After feeling that her wardrobe was inadequately chaotic compared to the standard suits of her male colleagues she designed a new wardrobe. Kahn's solution is a true uniform: she bought 15 identical silk shirts and several identical pairs of trousers. She wears the exact same thing to work every day.

Klaus Friedrich, an architect from Munich, points out that man is a gregarious animal and that architects wear black in order to be recognised as such, and if the designer is not recognised as a designer then "his glasses too are black and round."

Designers wear the most black when working. Sarah Owens, Dagna Salwa, Laurence Hau and Sandra Pfeiffer tend to relax their black uniforms when not at work or at university. Owens wears black three to five times a week, when she is working. Pfeiffer and Salwa, who both study design, wear colour in the summer when they are less active as designers. Hau wears less black at weekends. Many designers begin wearing black just as they first began identifying themselves as designers, at the beginning of their studies or careers. This is the case for almost every designer I interviewed: Owens, Hau, Salwa, Pfeiffer, Fabio Menet and Samira Schneuwly all began wearing black soon after they begin studying design.

The tendency towards stark simplicity and purity is a design tendency, a modernist tendency. Decoration and flamboyance is disliked by modernists. Instead minimalism, truth to materials, attention to detail, functionality and timelessness are the focus. Dieter Rams, a modernist industrial designer, said that "good design is as little design as possible". Herbert Schultes, a Munich architect, said that designers wear black "in order to be on the side of the purists and minimalists." Neutrality is a key word for modernists.

Modernists like Grotesk typefaces because they perceive them as neutral. They like black because black "goes with every colour", which enhances its neutrality.

Actually black is not a practical colour - it shows dirt fairly easily. Brown, olive or grey are more practical colours. This is obvious when we look at the clothes of farmers, of factory workers, of the military. Navy, khaki, olive, grey and brown are the colours we see most often, not black.

Nor is black is not really true to materials since cotton and wool are normally white and must be dyed black.

Black is not really neutral since, as I showed earlier, it's been tied up in all sorts of complex political movements from the far right to the far left.

Black is not modern, it's been the uniform of professionals for hundreds of years.

But, black is perceived as being all these things and what is perceived is real. We're dealing with visual identity and perception. That’s all clothing is. When it comes to identity, what is perceived is real.

Patrik Schumacher, a London architect, calls black "a random group dynamic phenomenon" and explains that the only rational reason we have for wearing black is the choice of shape over colour, referring to the inherent silhouette created by black clothing and in order to contrast black with the neutral white of architecture.

Another true advantage of black clothing is its social flexibility. Black can be worn in the largest variety of social situations without disapproval. Black can be worn at a construction site, at dinner, in the office, on a plane, in a night club, in all social and political situations.

Designers do have expcetions to their rules of black. Not only is their dress code much more relaxed at weekends and during the summer but things like shoes and socks, keychains and scarves are exempt from the all black rule.

Designers who only wear one major black item, either top or bottoms, will usually stick with a monochrome palette and wear the other item in white or grey. Bright colours are rarely worn. Hau will only wear colour if a dress code requires it. Fabio Menet explains that when creating a design layout he needs a strict reason for the use of colour. He feels the same need for the justification of colour when designing his wardrobe. Dagna Salwa normally only wears colourful accessories or t-shirts and Samira Schneuwly has a blue keyring.

Designers may wear black because black is sombre, humble, professional, fashionable and timeless. They may wear it because it carries a certain political meaning for them or simply because it makes them look good. They wear it because it is the uniform of designers everywhere, because it makes them recognisable as designers and because it makes them draw strength from this group.

Most designers essentially wear black because they are not creative people and prefer to conform to the group. They wear black because it makes them fit in with their peers and because black best reflects the modernist design tradition they choose to work in.