SOME of the great Italian high Renaissance painters, such as Raphael, Tintoretto and Lorenzo Lotto, are renowned for their complex, extravagant hues. Their secret, it seems, was to add small particles of glass to their paints.
Adding the glass helps bring the paint colours to life by making them appear more translucent, and it was already known that glass was added to two paints called lead tin yellow and smalt blue that were used in 16th-century Italy.
But Barbara Berrie, a chemist at the National Gallery of Art in Washington DC, has now discovered that painters also added tiny glass…
