FRAGILE! HANDLE WITH CARE!

THE PREDICTION OF DAMAGE FOR 18TH-CENTURY PASTELS SUBJECTED TO VIBRATIONS INDUCED DURING TRANSPORTATION 

18th-century pastel paintings are a group of objects that are often requested for loan. However, they are considered to be one of the most fragile artworks because the medium is poorly bound to the support. Vibrations have been identified as one of the most important risk factors during transport. However, little data is available to predict what vibration conditions (strength and duration) are acceptable. The objective of this project is to determine acceptable vibration conditions for the transport of pastels.  

For this work, vibration testing was conducted on mock-ups, made using handmade paper and pastel sticks that were selected after a technical survey of the Rijksmuseum collection. One set of mock-ups was made by hand, another one with a scanner able to precisely control the amount of medium applied on the support. Vibration testing was conducted by mounting the mock-ups on a biaxial stretcher, simulating stretched historical pastel paintings. Tests were conducted at several different vibration levels, and the number of cycles to failure was determined.  

An important question was whether there is a cumulative effect after continued vibration, or if the particles would fall off if particle vibration cycles exceed the strength of the particle/paper bond. The results so far indicate that the effect of vibrations is a cumulative one. Further, initial tests with mock-ups with fixative show that it takes longer for a pastel with a fixative to fail than one without. 

PUBLICATIONS (SELECTION):

1. (Bill) Wei, Art Conservation, Mechanical Properties and Testing of Materials, Jenny Stanford Publishing, 2021, 164 pages
2. Sauvage, H. Stratis, L. Harrison, “Pastel roundtable – A study day at the National Gallery, London, April 30, 2018”, Journal of Paper conservation, vol. 19, 1, 2018, p. 33–35.
3. Sauvage, W. (Bill) Wei, M. Martinez, “When Conservation Meets Engineering: Predicting the Damaging Effects of Vibrations on Pastel Paintings”, Studies in Conservation, 2018, 63:sup1, p. 418–420.
4. (Bill) Wei, S. Watts, T. Seddon, D. Crombie, “Protecting Museum Collections from Vibrations Due to Construction: Vibration Statistics, Limits, Flexibility and Cooperation”, Studies in Conservation, 2018, 63:sup1, p. 293-300.
5. (Bill) Wei, L. Sauvage, J. Wölk, “Baseline limits for allowable vibrations for objects”, ICOM-CC 17th Triennial Conference Preprints Melbourne, 15–19 September 2014, ed. J. Bridgeland, art. 1516, Paris, ICOM, 7 pages.

Partially funded by the Migelien Gerritzen fund.

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