Pyroxyline Paintings by Siqueiros: Visual and Analytical Examination of His Painting Techniques

Abstract

The role of David Alfaro Siqueiros (1896-1974) and his use of pyroxyline-based paints are crucial in the transition from oil to acrylic paints. During the early 20th century, his experimentation with this innovative paint medium had a great impact on North American traditional painting techniques (1). Although Siqueiros's paintings labeled as 'pyroxyline-based paintings' are highly prone to decay, little scientific research has been actually done to verify the presence of a pyroxyline-based medium (2). Identification of this type of paint film is usually based on visual examination. Consequently, pyroxyline paintings have often been confused with other painting media. In order to obtain data on Siqueiros's pyroxyline-based paintings, five of his paintings that records cite were made with pyroxyline-based paints were analysed using Fourier transform infrared spectroscopy and light microscopy. Results indicate that visual characteristics assumed for pyroxylines are a misleading guide in the labeling of paintings. Only two of the five paint films analysed were pyroxyline-based paints, two were painted in oil and one was an acrylic. The poor conditions of paint films are more probably caused by Siqueiros's unorthodox painting technique rather that his use of pyroxyline-based paint.