21 Jun 2017

The history of pigments

From Nights, 7:15 pm on 21 June 2017

From cow's urine to beetle's blood, the ingredients that have been used to make pigments are equally weird and wonderful.

David Coles' Melbourne exhibition Chromotopia: A History of Colour tracks the history of over 200 pigments – some deadly, some revolting and some dangerous.

First off, we have to remember that most of the colours that we see on a daily basis are synthetic, created by pigments from dyes or minerals rather than by light, Coles says.

"The colour we experience all around us in the physical world – from plastics and paper and cars and cosmetics – they actually come from something."

The first synthetic pigment was Egyptian blue, created 5,500 years ago, but another exquisite bright blue shade 'YInMn Blue' (which stands for Yttrium, Indium and Manganese) was discovered quite recently, by chemistry students at the University of Oregon in 2009.

YInMn Blue

Photo: Public domain

The deep brown substance which coloured most writing ink until the early 20th century came from nut-like growths on an oak tree, known as oak galls. 

"In essence, [and oak gall is] a blister that the oak tree creates when the European wasp lays its eggs on the soft buds of the tree ...The oak, to protect itself from diseases, grows this nut-like growth around it, called an oak gall."

These growths then fill up with gallotannic acid – a concentrated version of tannin.

Until Titanium White came along in the 20th century, Lead White was commonly used in oil paintings and cosmetics such as face powder, despite being poisonous.

Indian Yellow comes from the brightly coloured urine of cows fed exclusively on mango leaves by the herdsmen of Monghyr.

"They would collect that, concentrate it by boiling and then mould it into balls, which were then dried out."

Most of these colours were superseded when modern chemistry exploded – "it was much cheaper and safer and less cruel" – but one is still in common use.

Cochineal powder

Photo: Flickr user madame.lure / CC BY SA 2.0

The blood of a tiny Central America beetle is used in the deep crimson red colour Carmine, aka cochineal.

14,000 insects are needed to produce 100 grams of pigment, Coles says.

Cochineal is one of the few FDA-approved natural colours so it ends up in a lot of processed foods and beverages, including blackcurrant juice – so strict vegetarians beware.

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