But much of that new output, and most of the reserve capacity, is in the form of heavier oils that are costlier to refine and for which there is less thirst.
Rembrandt Harmenszoon van Rijn, who died in 1669 aged 63, is widely regarded as one of the most prolific self portraitists, thought to have painted 40-50 pictures of himself in oils and used himself as a model in 32 etchings and seven drawings.