Fire is one of the most catastrophic agents of deterioration, in part because it typically includes several agents affecting collections at once. Obviously, high heat can burn or char an artifact. Falling debris and the release of fire suppression measures can also cause damage from physical forces. Collections might contain explosives or materials that ignite. Sooty smoke can deposit on the surfaces of objects as an acidic, greasy, and abrasive pollutant. Many items that have gone through a fire have a strong smoke smell. Fire suppression usually involves water and subsequent water damage to collections. Finally, the chaotic time following a fire can lead to dissociation or even theft. Let’s consider examples of these threats.
Figure 1 shows a desk that suffered a fire, leaving it partially charred. Figure 2 shows melted plastic adhered to the back of the desk. It seems the desk had a plastic dustcover that only partially covered the desk, and became stuck to the wood where it melted. Figure 3 shows the plexi glazing of a framed artwork completely melted from high heat. The paper artwork fell to the ground and was destroyed.
Be aware of items in your collection that might be a fire danger. Cellulose nitrate is an early plastic that was often used in photographic negatives and motion picture film. This material breaks down over time and becomes unstable, sometimes even spontaneously igniting. Typically, these materials are kept in cold storage to slow deterioration. Early fire extinguishers sometimes contain dangerous chemicals, particularly carbon tetrachloride (CCl4). This chemical is toxic, and when heated produces poisonous phosgene gas. Old brass fire extinguishers are attractive, collectable, and common in museum collections. In some cases, the local fire department may be able to assist a museum in drilling a small hole in the extinguisher to remove the dangerous contents but allow the object to remain in the collection. Natural history fluid specimen collections are sometimes stored in flammable liquids. Old ordnance like cannonballs can sometimes contain explosives that endanger lives and property in a fire. Occasionally these can be drilled to remove the dangerous contents, but sometimes it is necessary to sacrifice the artifact. An example of this happened at the Sheldon Jackson Museum in Sitka some years ago. Curator Rosemary Carlton described the process in a 2008 article, “All Quiet on Your Museum Front?”
The smoke produced from combustion is a special kind of pollutant. It produces greasy, sharp, acidic particles that can be difficult to remove from surfaces. In 1983, the Alaska State Museum suffered a “puff back” from its boiler system. The resulting cloud of soot settled on more than 15,000 artifacts and required a multi-year effort to clean and document the damage. Smooth, less-porous surfaces can sometimes be successfully cleaned with a kind of vulcanized rubber sponge called a “soot sponge.” Gonzo and Absorene are two brand names. These sponges, often available in hardware stores and sometimes marketed for “pet hair removal” can be cut up into small cubes, using each of the surfaces for cleaning. When each of the six sides of the cube is soiled, the cube can be sliced like a loaf of bread, using both sides of the slice to maximize the cleaning power of the sponge. Porous materials, such as white feathers on taxidermy birds or paper items (figure 4) are more difficult to clean and probably require professional assistance.
In the wake of a fire, records may be destroyed, objects dissociated from their information, and objects can even be stolen. Alaska’s moon rocks were stolen in the 1970s following a museum fire. See the section on theft and vandalism for the tale. Good record keeping and an emergency response plan that helps keep collections organized is crucial when disaster hits.
Good museum policy can help prevent fire in the first place. Electrical malfunction is a common cause of fires, thus anything plugged in should be well maintained and monitored. Portable heaters are a particular concern, especially in Alaska. Many buildings in Alaska have outdated or improvised electrical systems, which can add to the risk. Candles and other sources of open flame are typically prohibited in museums. Smoke detectors and fire suppression systems should be in good working order. The fire marshal of your town is happy to schedule a walk-through of your facility to identify potential risks. In the old overcrowded storage of the Alaska State Museum building, we struggled to keep collections off the tops of museum cabinets where they might block fire suppression systems from extinguishing a fire. In our old building (built in 1967 and torn down in 2014), we faced challenges from asbestos in many areas. Here were the pros and cons we considered when developing the fire suppression system for our new building.
Systems based on the release of a gas to smother the fire have been popular because they do not get the collection wet. Several Alaskan institutions, including the old Alaska State Museum, used Halon. With the Clean Air Act of 1994, its production was discontinued because it depletes the ozone layer of the planet. It continues to be legal to have a Halon system if one is already installed, but maintaining them is increasingly challenging and expensive. FM-200 (heptaflouropropane, a halogenated alkane) has been a popular replacement for Halogen. FM-200 emits hydrofluoric acid at very high temperatures, but at that point the collection is burned anyway. In order to smother a fire in a timely manner, gas will be propelled with great force. In our old museum, we lived in fear of a discharge because that force would have blown off ceiling tiles and contaminated the room with asbestos. In November 2006, a fire suppression system with a nitrogen propellant went off in the Museum of Ethnology in Vienna. Large numbers of objects were thrown from shelves and damaged, and dust was even blown into closed cabinets. Since nitrogen is odorless, a marker gas had been added and it left a tacky film on everything. Some jurisdictions require sprinkler systems in addition to chemical suppression systems. Another major disadvantage of a gas system is that the collection is not protected following a discharge until the system can be re-charged. In Alaska, that might take several months. Gas systems work by eliminating oxygen, which would be an asphyxiation hazard for anyone trapped in the space. Also, in order to eliminate oxygen, the space needs to be made airtight.
Wet pipe systems are the most common for fire suppression, with good track record and fast response. They are simple, reliable, time-tested, and have the fewest number of components to go wrong. There is low installation and maintenance expense, as well as ease of modification with renovations. Several of the largest museums in Alaska have wet pipe systems with VESDA (Very Early Smoke Detection Apparatus) in certain areas for higher levels of smoke detection. Regular maintenance of a wet pipe system includes discharge to the outside through an external valve. The top causes of failure are freezing temperatures or knocking off a sprinkler head. A typical sprinkler head releases 25 gallons per minute (GPM). A fire hose releases 150-250 gallons per minute. Many years ago, construction in the basement of the old Alaska State Museum building knocked the head off a sprinkler, and quick action was needed to shut down the water source. Collections were not harmed, but cleaning up the water was quite a task. Depending on the source cited, 60-80% of fires are put out with discharge from just 1-2 sprinkler heads. Sprinkler heads are typically activated by a fusible element that melts or they have a “frangible glass bulb” with liquid inside. The bulb is color-coded and ruptures at a certain temperature. Sprinkler heads have a failure rate of one head per 16 million installed annually. Unlike a gas system, there is a short period of down time of vulnerability after discharge…just replace the sprinkler heads and turn on the water again.
A dry pipe sprinkler system is one in which pipes are filled with pressurized air or nitrogen, rather than water. This air holds a remote valve, known as a dry pipe valve, in a closed position. When fire causes the seal in the sprinkler head to melt, the gas pressure is released and the flapper valve opens, allowing water through. This kind of system is commonly used in areas prone to pipe freezing, like warehouses, attics, and outdoor loading docks. One disadvantage of a dry pipe system is the longer delay for response, up to 60 seconds from the time a sprinkler head opens until water comes out. Failure of the compressed gas means the pipes fill with water, but as long as the seals on the sprinkler head are not melted, the water will not come out. A similar system is called a pre-conditioned dry pipe. In this case, electronic sensors activate the valve. There are two in each zone, and both must go off to activate the system. If one is not functioning, neither does the sprinkler. This system is computer-controlled. There is a manual release possible, but it must be located where it can be safely reached during a fire. In some jurisdictions, the fire marshal may require a demonstration to prove it is working (i.e. flooding the pipes). Corrosion inside the pipe can make a rust-water sludge that gums up the pre-action. Pre-condition systems have a higher cost of installation and maintenance, and modification is difficult. This might not be an ideal system for many Alaskan institutions.
A “deluge system” is a wet or dry pipe system that includes open heads, which just let the water flow, instead of sealed individual heads that release as needed. The open kind are also called “automatic” heads. These are not recommended for museums, but this is the kind of system we see in movies and music videos. Deluge systems are recommended for high-hazard areas like power plants, chemical storage areas, and aircraft hangars.
In recent years, mist systems have gained in popularity because only a few gallons of water are required to put out a fire, resulting in much less water damage. The small water particles are thought to bind up smoke particles and result in less soot damage. The tiny mist droplets give an increased surface area, helping to reduce temperature and oxygen quickly in the space. Droplets turn to steam and bind up available oxygen, acting rather like a gas to smother the fire. This might work better in a large fire than a small one. Water is released at high pressure (1000 psi) that is generated by gas or a high-pressure pump. Water comes from a supply pipe, dedicated tank, or canisters. If canisters or tanks are used, there will be a period of vulnerability while are refilled following a discharge. Discharge is usually triggered by electronic sensors. Research on mist systems began in 1960s but has been spurred on more recently as Halon is being phased out and there are new regulations for fire suppression in certain spaces, such as on board cruise ships. A 3-D array of pipes is needed throughout the room with a nozzle every few feet, which might be a challenge in collections storage spaces and exhibit galleries where the equipment might be obstructed. Piping is usually ½” diameter stainless steel pre-fabricated and then assembled on site with simple compression fittings. New hybrid systems combing mist and gas are also coming on the market. Until they are much better established, such systems are probably not appropriate for most Alaskan institutions.
Items in your collection that have already experienced a fire event might have ongoing condition issues. Charred areas are more brittle and delicate than they were before the fire (figure 5). In some cases, charred items might need to be isolated from other items in the collection to prevent soot rubbing off onto other objects. Sometimes, collections that have experienced a fire have a smoky smell.
Ozone is sometimes used by commercial companies to get rid of odors, especially smoke odor after a fire. Museum standards consider this inappropriate, since ozone is a strong oxidizing agent. Risks associated with exposing museum collections to ozone includes damage to plastics, cracking of rubber and rubberized fabrics, fading of dyes, inks, and watercolors, embrittlement of cellulosic materials such as cotton and paper, deterioration of leather, wool, and other protein materials, oxidation of silver and iron, and premature aging of most organic materials. These effects are exacerbated in high humidity conditions and can be worse in combination with other pollutants. There are odor absorbers on the market that can be enclosed in a plastic tote with an artifact (isolated from the object of course) and passively reduce the intensity of the smoke smell. A simple technique is to elevate the item within the tote and fill the bottom of the tote with a layer of kitty litter that contains zeolites. This odor reduction process may take many months, but is often effective and inexpensive.
Questions? Contact Us! The Alaska State Museum has an outreach mandate to help provide advice and expertise to museum professionals and other caretakers of Alaskan material culture.
Email Ellen at ellen.carrlee@alaska.gov or fill out our online contact form.
