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A Colour A Day: Week 38. 7 - 13 December - Cobalts
A Colour A Day: Week 38. 7 - 13 December - Cobalts, Jo Volley, 2020

Each pigment is bound in gum Arabic on W&N watercolour paper and read from left to right:Cobalt Violet DarkCobalt GreenCobalt Violet BrilliantCobalt Yellow PaleCobalt Green BluishCobalt Violet Cobalt Titanate Green

A Colour A Day
Week 38,  7 - 13 December 2020

Follow Jo Volley's A Colour a Day project,  a year-long project to celebrate one colour each day by recording a swatch of it,  on The Pigment Timeline Blog:  https://blogs.ucl.ac.uk/pigment-timeline .

This week’s colours are accompanied with a text by Robert Mead in response to the cobalts.

Cobalt: Pigment of Hope and Destruction

Robert Mead

Cobalt shares an entwined history with both painting and technology. The mineral is capable of producing a range of different colours - perhaps the most commonly known is Cobalt Blue. This is a cobalt aluminate pigment and was first discovered in 1775 – with further modern production achieved in 1777, where the moistening of aluminium compounds with a cobalt solution turned blue and strongly calcined.

A variety of other colours can be produced through cobalt; a range of violets can be created through a variety of different compounds – such as cobalt magnesium arsenate – and cobalt phosphate octahydrate. Cobalt Green has been made by multiple processes including the direct mixture of cobalt blue with ‘chromic’ yellow or a combination of cobalt and zinc or iron oxide. Cobalt Yellow is a potassium cobalt nitrate, first synthesised in 1831 – through the reaction between potassium nitrite and cobalt salts, creating a crystalline mass.

Using cobalt, we are able to produce range of wonderful and unique colours. However, as a mineral its demand has increased alongside the development of new technologies – as a key component of batteries in laptops, phones and increasingly electric cars. The main source of cobalt extraction is in The Democratic Republic of Congo, whose history of colonisation by Belgium from 1869–1908 through to its independence in the 1960s is entwined with the desire for its available supply of minerals such as diamonds, copper and uranium. Now major western companies such as Apple, Dell and Microsoft have bought into the mining industry there, as cobalt suppliers for their lithium batteries, this high demand has led to quarries operating with dangerous conditions and often using child labour.

Furthermore, both the pigment and the mineral itself hold highly toxic particles and when consumed or inhaled and can cause major health risk - increased through poor mining conditions. Further increasing the demand for cobalt is the development of electric cars. As we attempt to offset the climate crisis by moving to using electric vehicles, companies such as BMW and Tesla have also invested heavily in cobalt mining to acquire the material for powering them. In this case, cobalt is at the centre of paradox between hope for moving away from fossil fuels and towards clean electric energy and the negative consequences its acquisition results in.

Without sustainable mining methods, its production is tainted by this problematic discord.In reflecting on cobalt’s significance for our future, it seems prescient that it was the key ingredient in what was considered the doomsday weapon of the Cold War – the Cobalt Bomb (or C-Bomb), theoretically capable of wiping out all human life on the planet and featuring in films such as Beneath the Planet of the Apes and Dr Strangelove. The use of cobalt would allow a much higher level of fallout to be released from detonation, many times greater than the level of residual radiation still present in the strata of the Earth from the era of nuclear testing.

When we look at the alluring colours it can produce we can also consider that cobalt pigments are entwined with both our colonial and technological history and humanities attempts at both healing and destruction.


Robert Mead is a painter and PhD researcher at the Slade School of Fine Art. The aim of his research is to make paintings that form emotive connections between the viewer and our environment which draw them into wider hidden discourses. Robert says of his work; 'Moving through the strata of my paintings digs up histories and ghosts that we may not wish to confront but are bound to our past’ .

Each pigment is bound in gum Arabic on W&N watercolour paper and read from left to right:

Cobalt Violet Dark
Cobalt Green
Cobalt Violet Brilliant
Cobalt Yellow Pale
Cobalt Green Bluish
Cobalt Violet
Cobalt Titanate Green