The masterpieces hiding in old master paintings in pictures

Using x-rays and ultraviolet light, Alejandro Guijarro looks deep into the very fabric of old master paintings and finds a mysterious world of light and shade

Read more: https://www.theguardian.com/artanddesign/gallery/2017/feb/28/masterpieces-hiding-in-old-master-paintings-in-pictures-alejandro-guijarro