We are pleased to announce a new, online edition of the NICAS colloquium on Thursday 23 September 2021 from 12.00 to 13.00 hrs. The colloquium will take place online through Microsoft Teams. By clicking on the link below, the meeting will open in your browser.
Throughout the year, NICAS organises a bi-weekly Colloquium consisting of two short research lectures. It provides researchers with the opportunity to present ideas for, updates on or results of their activities. The NICAS Colloquium allows people to stay informed on a regular basis about the latest developments and results of research and to exchange information and expertise.
The chair of this colloquium will be Alba Alvarez Martin (Rijksmuseum)
The presenter is:
► René de la Rie – Wavelength Dependent Light Aging of Dammar Varnish
Impact on Norrish cleavage reactions in triterpenoid molecules and implications for accelerated aging experiments
The results of accelerated aging experiments are sometimes questioned. Norrish Type I cleavage reactions of carbonyl groups in dammar triterpenoids were studied at different wavelengths of UV exposure. Films of dammar resin were exposed to xenon arc irradiance, using long-path filters with varying cut-on wavelengths. The results were studied using gas chromatography mass spectrometry of the triterpenoid fraction. It was shown that -cleavage of carbonyl groups, leading to formation of A-seco compounds, takes place at wavelengths present in daylight filtered by window glass, thus validating the aging method. Claims that Xenon arc exposure leads to abnormal degradation appear incorrect. By eliminating UV entirely below 400 nm, Norrish reactions are inhibited.
E. René de la Rie has a doctorate in chemistry from the University of Amsterdam (UvA) and has been an adjunct professor (bijzonder hoogleraar) there as well as at the University of New York. He was head of the scientific research department of the National Gallery of Art, Washington, DC from 1989 until 2012. Before that he held positions at the Metropolitan Museum of Art, New York, the Training Program for Conservators (now UvA) and the Central Research Laboratory for Objects of Art and Science (later ICN, now RCE. He has published extensively and is currently active as a guest researcher at the Centre de Recherche sur la Conservation, Paris and at the UvA.