title: Pigment Degradation in Oil Paint Induced by Indoor Climate: Comparison of Visual and Computational Backscattered Electron Images.
abstract: For the first time the degradation of lead white pigment in mature oil paint has been used as an internal marker for the degree of saponification and hence chemical degradation of oil paint. Computational image analysis of the backscattered electron images quantified the degree of the intact lead white pigment versus the nonpigmented and lead-rich areas (degraded lead white) in the paint layers. This new methodology was applied to a series of paint samples taken from four painted wall hangings (dated 1778), which makes it possible to study the influence of indoor climate on chemical degradation of aged oil paintings. The visual interpretation and computational image analysis of the backscattered electron images revealed clear trends. The highest degree of lead white degradation in the room was found in samples from the north wall close to the windows, whereas degradation diminished further away from the window. Lead white from the south wall was less degraded, but showed a similar trend as in the paintings on the north wall. These results imply a strong relationship between chemical degradation of paint and location of the paint in the room.
authors.affiliation: 1Laboratory of Materials Science,Materials in Art and Archaeology,Delft University of Technology,Mekelweg 2,2628 CD Delft,The Netherlands.
authors.forename: Katrien
authors.initials: K
authors.lastname: Keune
authors.affiliation: 4Department of the Built Environment,Eindhoven University of Technology,Den Dolech 2,5612 AZ Eindhoven,The Netherlands.
authors.forename: Rick P
authors.initials: RP
authors.lastname: Kramer
authors.affiliation: 4Department of the Built Environment,Eindhoven University of Technology,Den Dolech 2,5612 AZ Eindhoven,The Netherlands.
authors.forename: Zara
authors.initials: Z
authors.lastname: Huijbregts
authors.affiliation: 4Department of the Built Environment,Eindhoven University of Technology,Den Dolech 2,5612 AZ Eindhoven,The Netherlands.
authors.forename: Henk L
authors.initials: HL
authors.lastname: Schellen
authors.affiliation: 5Cultural Heritage Agency of The Netherlands,Smallepad 5,3811 MG Amersfoort,The Netherlands.
authors.forename: Marc H L
authors.initials: MH
authors.lastname: Stappers
authors.affiliation: 1Laboratory of Materials Science,Materials in Art and Archaeology,Delft University of Technology,Mekelweg 2,2628 CD Delft,The Netherlands.
authors.forename: Margriet H
authors.initials: MH
authors.lastname: van Eikema Hommes
keywords: computational image analysis; indoor climate; lead soap; pigment degradation; scanning electron microscopy