Bag End Helps Preserve 18th Century Pastel Artwork

Fragile! Handle With Care

A highly customized laboratory subwoofer was designed for Delft University of Technology in the Netherlands to aid in preservation research of 18th century pastel artwork.

Pastel paintings are considered one of the most fragile artworks. Because the medium is barely attached to the support, each movement is a risk. In theory, museums don’t lend pastels; but in practice, the number of exhibitions including pastels is increasing, which means that pastels are moved.

Standards exist for light, relative humidity and temperature, but risks related to vibrations are still misunderstood and under-estimated. A PhD was initiated in 2014 to provide standards for vibrations, in collaboration with the Rijksmuseum, the Cultural Heritage Agency of the Netherlands and the Delft University of Technology.

Adopting a phenomenological approach, the present research aims at establishing a methodology to predict damage for 18th century pastel artwork subjected to vibrations induced during transportation. This will help conservators answering two questions: “What is the maximum vibration level acceptable for one transport?” and “How long and how many times can one pastel be transported this way?”

For the fatigue testing, a customized Bag End 18” subwoofer is used to simulate vibrations induced by transport. A pure sinusoidal signal is produced by a function generator and acoustical vibrations are applied to the mock-up artwork by the subwoofer. The subwoofer and art work are positioned in precise physical proximity providing a repeatable calabrated test. The testing stops when failure, or an unacceptable damage level has been reached and the corresponding vibrational data is recorded.

For the first time, the concept of fatigue life and cumulative damage will be brought from engineering into conservation, following three main research axes: the definition of failure, or unacceptable damage, as combination of visual perception and pastel surface properties; the characterization of vibration loads induced by transport; and the establishment of a relationship between pastels’ properties, vibration level, duration and damage.

Pastel drawing mounted horizontally on testing frame above Bag End Subwoofer

Pastel drawing mounted above Bag End S18 subwoofer

Leila Sauvage
(Rijksmuseum/Delft University of Technology)
PhD Research Project

Participating researchers:
Rinze Benedictus (supervisor),
Bill Wei (supervisor),
Marcias Martinez (supervisor),
William Sethares, Robert Erdmann

Institutions involved:
Rijksmuseum, Delft University of Technology,
Cultural Heritage Agency of the Netherlands,
Wisconsin University