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Modern oil paint,
industrially produced and sold in tubes as ready-made, diffused
amongst artists since the end of the XX century. Modern oil
paints present significant compositional differences with
traditional natural oil paints. The introduction in the
commercial paint formulations used in artworks of low cost lipid
sources, surfactants, stabilizers and thinners necessary for
long term stability and industrial workability is demonstrated
to cause challenging conservation problems. Alkyds paints are
oil-modified polyesters synthesized from polyols, aromatic
polybasic acids and different weight percentages of oil/fatty
acids, and have been commonly used as binders in artist paints
and coating since the 1940s. Preservation of artworks containing
modern oil-based industrial paints requires the availability of
suitable analytical tools and a better knowledge of degradation
pathways of modern oil-based paints.
A new analytical approach based on the integration of three
different mass spectrometric techniques was developed and used
for the characterization of plant oils, modern oil paint,
commercial alkyd paints, and industrial alkyd resins, before,
during and after laboratory ageing treatments.
• Gas chromatography-mass spectrometry was successfully applied
for the determination of the fatty acid profile and aromatic
fractions of the resins after hydrolysis;
• High performance liquid chromatography coupled with
electrospray ionization mass spectrometry with a tandem
quadrupole-time-of-flight mass spectrometry allowed us to
characterize triglycerides, diglycerides and the pentaerythritol
and phthalic acid esters when present;
• Flow Injection analysis was used as a rapid method to evaluate
the presence of possible additives such as synthetic polymers.
This approach was applied to evaluate the chemical modifications
of plant oils, oil paints and alkyd resins during artificial
ageing. The combined analytical approach was successfully
applied for the characterization of paint samples collected from
case-studies.
Published papers
• Jacopo La Nasa, Ilaria Degano, Elisa Ghelardi, Francesca
Modugno, Maria Perla Colombini, “Core shell stationary phases
for a novel separation of triglycerides in plant oils by high
performance liquid chromatography with
electrospray-quadrupole-time of flight mass spectrometer”,
Journal of Chromatography A, 2013, vol. 1308, p 114-124
• Jacopo La Nasa, Ilaria Degano, Francesca Modugno, Maria Perla
Colombini, “Alkyd paints in art: characterization using
integrated mass spectrometry”, Analytica Chimica Acta, 2013,
vol. 797, p 64–80
• Jacopo La Nasa, Ilaria Degano, Francesca Modugno, Maria Perla
Colombini, “Effects of acetic acid vapour on the ageing of alkyd
paint layers: multi-analytical approach for the evaluation of
the degradation processes”, Polymer Degradation and Stability,
2014, vol. 105, p 257-264
• Jacopo La Nasa, Ilaria Degano, Francesca Modugno, Maria Perla
Colombini, “Industrial alkyd resins: characterization of
pentaerythritol and phthalic acid esters using integrated mass
spectrometry”, Rapid Communication in Mass Spectrometry, 2014,
in press |
