3 3. SALVAGE AND THE INITIAL RESPONSE TO SOOT

The fire at the Royal Saskatchewan Museum was unique in the extensive soot damage it produced. Nevertheless, fires of any size can emit tremendous amounts of smoke within minutes before they are brought under control. This is particularly true if the fire is in a “modern room” fitted with fire-retardant polymeric materials, such as insulation, that release large amounts of soot.

Soot removal will take up the bulk of recovery time following a museum fire. Conservators at the RSM found that the degree of soot removal during the recovery stage after a disaster (when objects receive a deep cleaning) can be enhanced by the application of specific procedures and techniques during the first couple of weeks following a fire (the response stage). These procedures and techniques acknowledge the unique characteristics of soot that make the process of its removal from object surfaces more complex (see Spafford-Ricci and Graham 2000).

Soot becomes more difficult to remove over time, a fact that conservators involved in the RSM cleaning discovered from one week to the next. Soot is often acidic, as it was in the case of the RSM soot, increasing the necessity to remove it quickly. Moreover, soot agglomerations are easily broken into minute particles of soot that pigment, and become physically trapped within even the smoothest of surfaces. To be most successful, salvage of soot-covered objects should attempt to minimize pressure, disruption, and dispersion of the soot layer, all of which will tend to drive the soot farther into the surface of the object.

The RSM conservators developed effective procedures that can be implemented in the response phase (i.e., usually the first two weeks) following a fire and in the salvage of soot-covered objects.

3.1 3.1 POSTING A WARNING SIGN

The front lines of a disaster are a confusing and busy place, and conservators will rarely have control over all areas. Notices that caution against touching sooty surfaces should be prepared as part of the disaster contingency preparations and be ready for posting following a fire, whether it is a full-scale museum fire or a localized fire. The “don't touch” signage can state that if a sooty object is touched, the pressure will disperse the soot and embed it into the surface, thus making the object uncleanable. Although such precautions may seem obvious, few people can resist running their fingers over a fresh layer of soot. The multitude of inspectors, officials, media, and managers who will tour the site within the first few days following a disaster are in special need of this reminder.

3.2 3.2 TRIAGE

Following a fire, collections should be prioritized for salvage and conservation treatment according to the type of object and its relative sensitivity to soot damage. Objects with charred areas and structural damage are obviously the most unstable and should be given first priority. Collections can then be prioritized as follows: porous surfaces are more sensitive than nonporous surfaces, intricate surfaces are more sensitive than smooth surfaces, and organic materials are more sensitive than inorganic materials; objects can be further separated according to the degree of sootiness, with those that are less sooty often being at less risk. Objects or groups of objects thus prioritized can be recorded on a master table so that the salvage team can indicate the status of the salvage operations for each object group. This master table will aid in coordination of salvage operations, which are usually chaotic and involve a changing roster of persons working concurrently in different locations.

3.3 3.3 REMOVAL OF SOOT BY VACUUMING

Vacuuming is the one active step that must take place during salvage of soot and fire-damaged materials. The highest degree of soot removal by vacuuming is possible only if an artifact is vacuumed on-site during salvage before it is touched, and certainly before it is packed and moved. Those participating in collection salvage will require disposable coveralls and a particulate mask. Portable canister vacuums such as shop vacuums or small canister vacuums should have a long length of hose complete with a crevice tool, a circular nozzle (i.e., a brush attachment with bristles cut back), and mini-attachments as required. Vacuum attachments will require frequent cleaning to decrease soot transfer. High-efficiency particle air (HEPA) filter vacuums are recommended for treatment of natural history specimens.

Where possible, vacuuming should be carried out with direct use of the vacuum nozzle and without the use of a screen or brush, which may embed soot in the surface. For best results, the vacuum nozzle should not touch the surface of the object. For firm objects, it is possible to hold a crevice tool above the surface of the object propped on a finger, which is passed over an already cleaned area (fig. 9). The circular vacuum cleaner attachment (e.g., a brush attachment with bristles cut back) can also be used directly on a surface, which is then pulled upward to repeat the process in an adjacent area. To avoid dispersing a soot layer, it is essential that an object be vacuumed “as it is found”: for example, a textile that is folded should not be unfolded. Surfaces should be vacuumed first and then cleaning can proceed to inner areas and crevices. To provide for the most controlled movements, vacuuming is best done with assistance: for example, one person may hold a painting while another applies the vacuum.

Fig. 9.

Vacuuming of a diorama painting using a crevice tool propped on a finger

At the RSM, vacuuming was the first step in a very effective progressive cleaning procedure for soot removal that proceeded from vacuuming to dry-surface-cleaning methods and then as needed to wet-cleaning agents.

3.4 3.4 HANDLING

Careful handling is imperative when dealing with soot-damaged artifacts because soot agglomerations can be dispersed and tiny soot particles integrated into an object's surface. Handling of sooty objects should be minimized during both the response and the recovery phases. Moving of artifacts from one location to another should, therefore, be undertaken only when necessary and only after the artifacts have received direct vacuuming. But, even after vacuuming, specific handling procedures must be followed to avoid dispersing the remaining soot. Objects should be carried “as they are” so that soot is not disturbed and dispersed into the object: for example, a folded item should not be unfolded and a stack of documents should not be separated. Direct pressure on the sooty layer should be avoided by enlisting the aid of another person in the handling process, by using handling aids such as carrying boards, and by carrying objects by auxiliary features such as by the base on a natural history specimen or by the frame on a painting.

3.4.1 3.5 TEMPORARY STORAGE

During a fire recovery, many objects will be in temporary storage spaces awaiting cleaning. Temporary storage conditions for sooty material should be dry to avoid activation of acidic materials through moisture contact. This consideration becomes particularly important if soot-damaged objects remain in a location that is also being recovered after a disaster, since the processes of cleaning carpets, walls, etc. involve use of aqueous cleaners. A storage location should be chosen so that it is the object's permanent home while awaiting recovery, and it should be secure. The objects should be stored “as they are”: not unfolded or opened. Stacking and close wrapping for storage should be avoided so as to minimize pressure on the soot layer. If a temporary storage location is in the same building as the fire site, polyethylene film draping can be used to loosely cover the storage units, and consideration should be given to sealing off this area (including the vents) so that soot is not transferred from other areas of the building.