Aging Characteristics of Surfactant Components
Two parallel studies were carried out at Winterthur by Janice Carlson and Chris Peterson—based on 1996 experiments by Richard Wolbers and Janice Carlson—to evaluate the deterioration products of representative surfactants already in use (or likely to be used) for surface cleaning: (A) the aging of surfactants on a polytetra-fluoroethylene film and (B) the aging of surfactants on a linseed oil film. The surfactants were found to have minimal effect on the surface. Some also appeared more stable than others. This information will help conservators in selecting the surfactant for a gel formulation.
Aging Study "A"
- Reference spectra of a pilot array of nonionic, cationic and anionic surfactants were obtained by Fourier Transform Infrared (FTIR) spectroscopy prior to artificial aging of the surfactant samples.
- Samples were artificially exposed to 72-hour cycles, an equivalent of 20 to 30 years of normal ambient conditions.
- Ethomeen C-12 and C-25 samples were removed at pre-determined intervals for analysis by FTIR.
- The volatile components of Ethomeens were measured using Gas Chromatography-Mass Spectrometry (GC-MS).
- The surfactant aging tests were rerun with samplings at earlier intervals in order to determine the response in the initial period.
Aging Study "B"
- Small amounts of the Ethomeens were applied to a linseed-oil film, dried, and exposed to 72-hour cycles of artificial aging. FTIR spectra were recorded and small sections were analyzed by GC-MS.
- The artificial aging and GC-MS analysis on samples of a model paint film were repeated with the first sampling taking place at an earlier stage, and successive samplings at shorter intervals.