Session 9: Preventive Conservation (Lizzie Woolley/ Catherine Higgitt and Tomasz Galikowski)

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Presenter Lizzie Woolley discussed the "Vibration Monitoring of Daniel Maclise’s Wall Painting at Trafalgar."

When it comes to vibration research in preventive conservation, the UK’s Houses of Parliament or Palace of Westminster pose a new challenge not only for  architectural restoration, but most importantly the prevention of vibration in a working building to preserve the Trafalgar mural located behind the working space, involving the removal and replacement of the masonry.

Elizabeth Woolley and her conservation team have been involved in preparations for construction-related vibrations. They designed and installed physical protection for water and dust above the wall painting. MSR 145 data loggers, recording real time variations of the acceleration signals, were the key factor to understanding the different vibrations the working tools were producing.  The excessive vibration levels of some tools resulted in the elimination of their use; for example, use of metal and nylon hammers and chisels and the core drill were halted since these method required water and produced constant vibration. In some cases, these tools were still needed, and the conservation team took measures to dampen vibrations including bracing the mullion (central element between masonry) with tight-fitting timber frames on both the inside and outside. The presentation attendees were quite interested in this topic, and most of them congratulated the team’s amazing job of mitigating deterioration in such a high risk environment. They also asked questions such as:

“I am curious whether communicating the results of your monitoring and protocols with the teams working on site was challenging at all? How much supervision was needed to ensure that the teams followed the protocols you've established?”

Elizabeth Woolley responded:

 “We were fortunate to have a good working relationship with the other parties, even if I'm sure it would have been easier for them without our involvement! The main issue was 'creep' over long work periods - masons gradually forgetting about constraints over time, when we had to remind the masons of our work plans.”

The outcome of the project was to balance the conservation needs of inseparable components in the building and to identify which tools produced less extreme vibrations and to avoid them.

Finally, the longest session of the Congress concluded with a stimulating presentation by Catherine Higgitt and Tomasz Galikowski on "Protecting the National Gallery’s Paintings Collection from the Impact of Shock and Vibration during Building Work."

We welcomed Catherine, who was the last panelist of this session and who also researched vibrations during building works. But this time, the fpcus was directed towards paintings of different sizes, part of the collection of the National Gallery, London.  We understood already the difficulties faced by Elizabeth’s team at the Palace of Westminster, so we approached this presentation with some knowledge of a different approach for the intervention.

First of all, the team analyzed and monitored in situ vibrations from building work consisting of the use of demolition using heavy tools producing vibrations which transmitted through the walls. This testing informed the creation of risk assessment and methods to help mitigate this problem.

 One of the methods consisted of constructing test paintings with different weights to which they could incorporate different fittings with accelerometers. Test paintings were hung differently, some with chains from picture rails, the medium sized paintings with supported brackets, and smaller ones screwed directly to the wall. The conservator placed prototype fittings and backing pads as damping material to isolate the paintings from the wall. For the chains, the incorporation of elastomeric fittings were also needed. One of Catherine’s teammates, Tomasz Galikowski, dedicated to the acoustic data, helped her analyze the different vibration isolations of the fittings. He spoke about the use of spectral measurements to understand vibrational frequencies to determine the risk of damage, where vibrations are transmitted, and which fittings are best.

The introduction of pads, made from different damping materials in the fittings, and splitting the chains with elastomeric hangers, gave this team effective outcomes based on testing paintings of different sizes and weights. I do have to mention they had some difficulties. The decision was made to only use these adapted fittings and elastomeric hangers with selected medium sized lined canvas paintings with similar weight. All methods were very well received!

Well detailed information about vibrations analysis can be found by checking out the Session 9 paper presentations.

 

Author:

Carlos Izurieta is a senior student of conservation and restoration of paintings and sculptures at Universidad Politécnica de Valencia, Spain.