title: FTIR study of ageing of fast drying oil colour (FDOC) alkyd paint replicas.
abstract: We propose ATR-FTIR spectroscopy for the characterization of the spectral changes in alkyd resin from the Griffin Alkyd Fast Drying Oil Colour range (Winsor & Newton), occurring over 550 days (∼18 months) of natural ageing and over six months of artificial ageing under an acetic acid atmosphere. Acetic acid is one of the atmospheric pollutants found inside museums in concentrations that can have a significant effect on the works exhibited. During natural ageing we observed an increase and broadening of the OH group band around 3300 cm(-1) and an increase in bands in the region 1730-1680 cm(-1) due to carbonyl stretching. We found a broad band around 1635 cm(-1) likely due to CO stretching vibrations of β dichetons. These spectral changes are the result of autooxidation reactions during natural ageing and crosslinking, which then form f alcohols and carbonyl species. The increase in absorbance at 1635 cm(-1) was selected as a parameter to monitor the ageing process of paintings prepared with FDOC, without the need for any extractive procedure. FTIR spectra of paint replicas kept under an acetic acid atmosphere indicated the chemical groups involved in the reaction with acid, thus suggesting which spectral FTIR regions could be investigated in order to follow any degradation in real paintings. A red paint sample from a hyper-realistic artwork ("Racconta storie", 2003) by the Italian painter Patrizia Zara was investigated by FTIR in order to evaluate the effects of 10 years natural ageing on alkyd colours. The results obtained suggested that after the end of chemical drying (autooxidation), alkyd colours are very stable.
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Universita' di Pisa, Via Risorgimento 35, 56127 Pisa, Italy.
authors.forename: Celia
authors.initials: C
authors.lastname: Duce
authors.affiliation: National Research Council of Italy, CNR, Istituto di Chimica dei Composti Organo Metallici-ICCOM-UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Della Porta
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Universita' di Pisa, Via Risorgimento 35, 56127 Pisa, Italy.
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Tiné
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Universita' di Pisa, Via Risorgimento 35, 56127 Pisa, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Spepi
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Universita' di Pisa, Via Risorgimento 35, 56127 Pisa, Italy.
authors.forename: Lisa
authors.initials: L
authors.lastname: Ghezzi
authors.affiliation: National Research Council of Italy, CNR, Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: Maria Perla
authors.initials: MP
authors.lastname: Colombini
authors.affiliation: National Research Council of Italy, CNR, Istituto di Chimica dei Composti Organo Metallici-ICCOM-UOS Pisa, Area di Ricerca, Via G. Moruzzi 1, 56124 Pisa, Italy. Electronic address: bramanti@pi.iccom.cnr.it.
authors.forename: Emilia
authors.initials: E
authors.lastname: Bramanti
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D001154:Art; D002244:Carbon / Q000737:chemistry; D003116:Color; D003890:Desiccation; D008422:Materials Testing; D010150:Paint; D010151:Paintings; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors
chemical_list: D012997:Solvents; D002244:Carbon; D019342:Acetic Acid
keywords: ATR-FTIR; Alkyd paints; Artificial ageing; Natural ageing