Hard Dry Paint, Softening Tacky Paint, and Exuding Drips on Composition (1952) by Jean-Paul Riopelle

The painting Composition (1952) by Jean Paul Riopelle (1923–2002) is
part of the Henie Onstad Art Centre’s collection in Norway. Examination of the
painting revealed the presence of drips of soft medium exuding from the surface.
The main aim of this paper is to report chemical characteristics of its hard, soft and
dripping paints. Information was collected about Riopelle’s use of materials. Data
were obtained from microsamples by analysis with Scanning Electron Microscopy
with Energy Dispersive X-Ray (SEM-EDX) and Direct Temperature resolved Mass
Spectrometry (DTMS). Composition (1952) is painted with 26 different colours or
shades of paint. All these paints vary in their specific physical condition when tested
on the painting. Paints were classified into three categories: hard, soft, softer and
dripping. The most problematic of all paints contained cobalt blue pigment.
Dripping exudates show relative high DTMS features for polar compounds such
as azelaic acid and midchain-oxygen-functionalised stearic acids. Lower relative
amounts are present in softening paints. Hard paints are characterised by higher
relative amounts of saturated fatty acids ranging from palmitic (C16) to lignoceric
(C24) fatty acid. We infer that a physical separation mechanism is responsible for
formation of polar micelles that form from oxidising semidrying oils in the paints
used by Riopelle. Results from Composition (1952) are compared with another
painting by Riopelle from 1956 and one by Pierre Soulages from 1954.