Origin, meaning and uses of colours: blue

According to some recent studies, blue is the favourite colour of most people, regardless of their gender or place of origin. But why? Probably because its origins, meanings and applications. Read the article to find out all the curiosities about the colour blue.

In the industrial coating field, as in many other sectors, colour coding is a key tool for the interaction between coaters and customers in order to define the final appearance of a product, the one that will determine end users’ purchasing behaviours. Anyone dealing with surface treatments normally uses the most widespread classification systems, such as RAL, PANTONE, and NCS: the tints and shades included in them form a sort of common language that coaters use on a daily basis to understand and be understood by customers and to properly meet their aesthetic requirements.

Colour is also strategic in everyday life: just think of how important it is in the choice of a common purchase such as a car, or how decisive colour trend forecasts are for our sector, but also beyond: there even exist numerous experts, study groups, and companies whose daily work consists in monitoring and/or studying the different colour trends to be followed in the finishing of products that are ready to be launched on the market and meet (or not) the taste of end users.

We have chosen to inaugurate this new column with a brief analysis of blue, which is one of the three primary colours, i.e. one of the basic colours that combine with the other two, namely red and yellow, to form all the other colours of the visible spectrum.

The origin of the word blue

The word blue (in Italian blu, in French bleu, in Spanish and Portuguese azul, and in German blau) is generally traced back to two ancient words: Proto-Germanic blewaz (which referred to the colours grey, dark blue, and black) and Proto-Indo-European bhle-was, in which the root bhle meant not only “blue”, but also “the colour of light”, and in turn, referring to the concepts of blond and yellow as well, was also the origin of the Latin word flavus, i.e. yellow. The Romans used the term blavus, which came from the same root, with the meaning of “faded”, whereas to indicate blue shades they used the two terms cyaneus and caeruleus. The latter meant “the colour of the sky” (caelum in Latin) and it was sometimes used to refer to dark green and teal. The former (also the origin of cyan and cyanotic) derived from the ancient Greek kyanos, which, in turn, originated from the Proto-Indo-European root kwey, generally referring to white. Germanic blao, Norse blar, and Old Provençal blau, all indicating the colour blue, originated from here. The English word blue came from the former two, whereas it is from the latter that the French term bleu descended, of which Italian blu was an adaptation.

A brief history of blue

According to a Washington Post article from a few years ago, blue is the favourite colour of most people, regardless of their gender or place of origin. It is no coincidence that it was and still is ubiquitous on the web, probably because of the concepts of trust and reliability associated with it. However, this was not always the case, as the first traces of blue pigment use date back to the Egyptians some 6,000 years ago. Previously, the colour blue was not recognised: there is no trace of it in cave paintings, just as there is no reference to it in the Bible or in Homeric texts.

The Egyptians were therefore probably the first to appreciate the peculiarities of this tint found in the lapis lazuli extracted from the mines of Badakhshan, in north-eastern Afghanistan, which they set in jewellery or funerary masks. At the same time, they were never able to pulverise them into a pigment, as reported in an Il Post article. Around 2200 BC, however, they invented another type of blue pigment from a mixture of limestone, sand, and a copper-containing mineral (such as azurite or malachite), which they traded with Persians, Etruscans, Greeks, and Romans, thus spreading it. By heating this mixture, they subsequently obtained a matte blue glass to which egg white, gum, or glue were added to obtain a resistant varnish or ceramic glaze.

This Egyptian blue is considered to be the first pigment produced synthetically by humankind and remained the most widely used blue throughout the Greek-Roman era until at least the 4^th century AD, when other hues became more widespread, such as ultramarine blue (Afghanistan, 6^th century AD), one of the most valuable and expensive pigments, much sought after by European painters in the 14^th and 15^th centuries; Han blue (China), an inorganic pigment made with barium instead of calcium; and Maya blue (Central America), based on indigo, an organic pigment obtained from the leaves of certain leguminous plants, mixed with clay and then heated.

These hues remained unchanged until the late 18^th to early 19^th century, when chemistry developments led to the creation of new blue pigments, from cobalt blue, a cheaper alternative to ultramarine blue, to cerulean blue, Prussian blue, and the more recent Klein blue and YInMn blue, the latest discovery in this field.

Some applications of blue

From architecture to textiles, blue finds the most diverse applications. The colour of sky and water evokes tranquillity and confidence, which is perhaps one of the reasons why it is among the most appreciated tints.

In interior architecture, blue hues are chosen precisely to evoke these feelings of calm and serenity. Especially in marine environments, they integrate perfectly with the context. Blue shades that are reminiscent of water are often matched with the concept of clean energy, at least as much as the much popular (and, to some extent, abused) green ones.

Blue is the quintessential colour of jeans. The main reason for this is practical: all synthetic dyes penetrate firmly into the fabric’s fibres once heated, whereas indigo has the ability to stick only to the surface. This is why, during washing, some colour molecules escape from the fibres, giving denim the classic “vintage” faded effect that makes it an ever popular product.

“To feel blue” means “to feel sad”: as it evokes feelings of nostalgia and melancholy, this colour has even given its name to a whole musical genre: blues. This seems to be derived from an English expression, “to have the blue devils”, which, according to popular belief, referred to the state of confusion and sadness resulting from abstinence from alcohol. Hence the name given to a melancholic musical genre such as blues.

Fun facts about the blue colour

Did you know that before the mid-20^th century, blue was a feminine rather than masculine colour? Associated from Christianity onwards with the cloak of the Virgin Mary, it was recognised as a feminine tint, whereas red, recalling the blood of battle, courage, and tenacity, was a purely masculine colour. A US marketing strategy in the 1950s designed to sell more gendered clothes and toys reversed this trend. Since then, the colours blue and pink have taken on the connotations we know today.

What about night blue? Blue is the colour of the night sky when it is clear and serene because the gas molecules that make up the earth’s atmosphere only scatter blue light, which has a shorter wavelength, whereas longer wavelengths are absorbed.

And one last oddity: did you know that the sunset on planet Mars is blue? The “postcard” sent to us by the Curiosity rover’s Mast Camera towards the end of the 956^th day (or sol) since its arrival on Mars captures the Martian landscape at sunset, observed from inside Gale Crater. The bluish tint of the sky is due to the particles present in Mars’ atmosphere, which allow blue light to pass through more easily than others do.

French painter Yves Klein, the inventor of Klein Blue (see above), once stated that “blue has no dimensions, it is beyond dimensions”. It is perhaps because of this elusiveness that blue is and will remain one of the most popular colours ever.