In Paintings of Dick Ket, a painter in the school known as magic realism, paint had started to slide down because of impure linseed oil.

In the great wave of romanticism in the 19th and early 20th centuries, some painters became so absorbed in expression that they lost sight of the limitations of their materials. Ralph Albert Blakelock, the American romantic landscapist (1847-1919), delighted in the rich gloss of bitumen, a poor-drying, brown pigment, which…