Traditional painting varnishes project: preliminary report on natural and artificial aging and a note on the preparation of cross-sections

A variety of traditional varnishes were prepared for the colloquium and workshop, Varnishes: Authenticity and Permanence (Canadian Conservation Institute 1994). The varnishes were applied to various substrates, underwent artificial light-aging followed by dark storage, and natural aging both in light and dark conditions. Tristimulus Chromameter readings and gloss readings have been taken at regular intervals. This paper will report observations to a selection of the varnishes: those prepared with mastic, dammar and copal resins, and will summarise the data collected on their viscosity, film thickness, yellowing behaviour, and changes in gloss. Results of an investagation of the chemistry of the naturally aged and artificially light-aged mastic and dammar varnishes will be reported, and a brief note on the preparation of cross-selections and the use of Parylene