Appearances can be deceptive.

Next time you visit the National Gallery in London – take a look at The Annunciation (1311), by Ducci. (It’s in the West Wing, Room 51)

Cranfield’s Angela Brown urges us to take an even closer look at the skin tone on the faces. You will see how they have a decidedly greenish tinge to them. Things are not quite as they should be. At least as far as these flesh tones go. So what’s going on?

Early Renaissance Italian painters understood and exploited the neutralizing effects of one colour when mixed or used against its colour compliment. They often combined this result with the technique of underpainting to the give flesh tones more dynamism and realism.

Terre Verte, with its colour opposite a rosy-pink, proved a wonderful undermodelling paint for portrait painters and the technique became known as ‘Verdaccio’ underpainting.

It’s thought Ducci uses a similar method here as he built up the middle and shadow flesh tones. Over time, the pinker hues in the paint layers over the faces have faded and become more transparent revealing rather more of the layers of green paint underneath than intended.

So there you have it – not so much what’s going on as what’s going, going, gone.

(Editor’s note: our colours are considerably better than our jokes)

It may be tinctorially weak, but Terre Verte is a born survivor, well able to resist the combined efforts of sunlight, the elements and the passing of time, stubbornly and with good reason, still occupying a significant place in the painter’s pallet.

And seven centuries later, here’s one of our own colour makers crafting a batch of genuine Terre Verte Oil Colour on a triple roll paint mill. And for those who are interested, Terre Verte or ‘Green Earth’ is a form of clay, a mixture of celadonite and glauconite and another of nature’s gifts to colour makers and painters alike.

If you can’t get to see the Ducci’s painting for yourself, here’s a link to The National Gallery site for a virtual tour of your own.