One of the things that has puzzled researchers for years is how did the artists achieve the glorious colours that we see in The Book of Kells.

This kind of art, which was done by Medieval monks and scribes, is known as Illumination. This is because the gold and silver used in the paintings reflected light and shone brightly when the light landed on the pages. And to further enhance the effect, the metal was often burnished till it it was smooth and shone even more brightly. However, what makes this book more remarkable is the fact that it achieves its brilliant luminosity without the use of any gold or silver.

It is believed that the book was produced around the year 800 by the monks of St Columba, possibly in Iona, an island off the coast of western Scotland where he founded a monastery, or in Kells, in Meath in Ireland where the monks moved to after a Viking raid on Iona.

It was produced on vellum, a kind of parchment.

But what about the actual paints themselves?

For years, it was assumed what the colours were without scientific tests being done to find out and verify these assumptions. The results, when this was done, produced some unexpected surprises.

At the time, there were a number of pigments in common use and readily available, and these turned out to be as expected.

For example:
Red/Orange shades – came from red lead
Yellow – was provided by ochre and orpiment
Black – was provided by carbon from lamp black or burned bones,
Brown – came from iron gall ink.

Iron gall ink was a staple of scribes, being regularly used to write documents on parchment as far back as the Magna Carta and earlier. It is one of the reasons we have preserved historical archives that go back for hundreds of years. So this would have been readily available and known to the monks.

In the Book of Kells, white was produced from gypsum. White lead was more common in other medieval paintings of the same time period.

It was thought that the blue was lapis lazuli.

This colour was a very costly pigment, being mined in Afghanistan or Persia, and travelling across huge distances to reach Britain. It was a hard stone and required much pounding and grinding to yield its beautiful dark blue. And it required skill and familiarity to successfully produce the colour — too little work left impurities in the powdered pigment, on the other hand, too much grinding and it would change and lose its colour. Imagine, all doing that work for nothing!

It was so costly that the use of the colour was reserved usually for the Virgin Mary, a point where the sacred joined up with economics of production. Or in the case of a wealthy patron, the lavish use of this colour proclaimed his prestige boldy for all to see and admire.

To great surprise, it was found that blue was supplied by indigo, a plant, though the source of the indigo itself is not currently clear.

Indigo in Britain at the time could have come locally from a plant called woad, which is native to northern Europe. Woad was used as a blue dye for cloth as well as for body paint by the Celts as far back as Roman times. Remember the stories about Boudicca.

However, indigo was also produced from Indigofera tinctoria plant and imported from South East Asia via Syria and Alexandria to the western Europe, making it the most expensive pigment in the Medieval world at the time. We don’t know which kind of indigo was used,

What we do know is that the Vikings and the Celts did have amazing trade routes established with the Baltic and the Middle East and Mediterranean area.

From the combination of indigo and orpiment, greens were produced, as well by using verdigris, a colour based on copper.

And the delicate purples were another plant derived pigment, produced by orecin obtained from a lichen called rosella tinctoria.

It is from this restricted palette of colours and pigment that the the artist monks had to work to create their stunning effects, using a combination of pure colours and simple mixtures.

By considered and careful juxtaposition and simple layering, very striking contrasts could be built up making colour combinations that sing with variety and luminosity. By adding 3 or more layers over a base layer, subtle gradations of colour and texture could be built up from only a few starting colours.

The diverse and delicate elaborate designs of The Book of Kells are amongst the most famous and well loved Celtic art work in the world. And the skillful use of mineral pigments has preserved the art work brightly for more than 1300 years.