Emergency Procedure and Grab Bag Testing
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Simulated attack testing: Method
The new grab bag was tested to establish how successfully it could be used to limit damage to paintings caused by a corrosive attack. It was important to establish how easy it would be to operate while wearing the kind of PPE needed in the most extreme of cases, how effective the equipment and guidelines might be, and how easy the grab bag was to use under pressure. Simulated attacks on test panels were conducted using three different attack substances.
The test panels consisted of six panels that were of unknown age and technique, but appeared to be from the twentieth century and executed in oil. All six were varnished with a thin layer of dammar and framed in painted softwood frames, the rebates of which were lined with velvet. Following general National Gallery practice, the works were back-boarded and hung with usual gallery hardware.
The minimum amount of time to reach the gallery with the bag was established. The time for a conservator to get from the studio to collect the bag and get to the furthest most gallery space was evaluated. An extra period of time was added to allow for security to be called, and for them to contact the conservator. It was therefore estimated that a minimum of fifteen-minutes would be needed to reach the targeted painting before the recovery process could begin. When conservators are not on-site, for example, during late night openings and weekends, this period could be considerably longer.
Three substances were blind tested. These were an acid-based cleaner, an alkali-based toilet cleaner, and a solvent-based paint stripper. It was not possible to test the more hazardous substances due to health and safety concerns surrounding the location of the test wall. It must be noted that in not testing the most damaging of acids, which are the usual choice of the vandal, we would not be able to comment precisely on the performance of the whole recovery procedure when dealing with this particular material. The test would still provide indications of general damage reduction with acid substances and that in conducting the test, trying out all the equipment and PPE would still be of great value.
To compare the degree of damage limitation a control painting was used that would receive the substance but would not be treated using the grab bag procedure. One substance was pipetted onto two test paintings in tandem. Two three-milliliter cascades were placed on each painting, one beginning on the painted surface and the other at the top of the frame.
After a period of fifteen minutes, the painting was attended to by two gallery staff, in this instance one conservator and one other acting under the direction of the conservator. Following the instructions contained in the bag and assuming the area had been cordoned off, the gallery staff donned the full PPE, which consists of coveralls, gloves, masks, and safety goggles.
The next task was to establish the pH of the attack substance and then follow the flowchart allied to either an acidic, alkali, or neutral reading. The approach to mop-up differed depending on the material, and further action was required if the substance was thought to have reached the rebate of the frame. The substances were all made to pool in the rebate of the frames and removing the backboards and frames became a required part of the procedure.
Depending on the type of substance, the final orientation of the work was adopted in order to limit damage. After mopping up and unframing, panels were either placed horizontal (for acidic agents) or vertically (for alkaline and neutral agents) with increased air flow to aid the evaporation of the substance.
For a full discussion of the simulated attack testing results, please consult our article entitled 'Incident preparedness at the National Gallery: Developing a grab bag for rapid response to a corrosive attack' published in Studies in Conservation in 2014.