Residues After an Emergency

After an emergency event involving fire and/or water, different types of residues may be present on your collections and in your building:

  • Mold
  • Soot
  • Odors
  • Mud

Dealing with these residues safely and appropriately is essential for both the health of the responders and the collections.


Mold spores are found everywhere and thrive in warm, moist conditions. Mold will grow on a variety of surfaces and material types; it takes only 2-3 days for wet materials to go moldy at normal temperatures (68 to 72 degrees F). Some molds can cause eye and respiratory irritations, while others may cause severe and dangerous allergies in certain individuals.

To lessen the danger of mold developing after a water event:

  • Lower the temperature in the affected space below 65 degrees F. Most species of mold favor a higher temperature.
  • Lower the relative humidity in the space below 65%. Most species of mold favor more humid conditions.
  • Mop up standing water and remove wet collections and other wet materials from the space including saturated carpets, floor padding, and some building materials.
    • Materials that retain large quantities of water will keep the relative humidity level in the space high, slowing down the drying process.
    • Materials that remain wet for some time may harbor mold within them or beneath them.
  • Consider freezing suitable collections materials that you will not be able to dry within 2–3 days (see section on freezing).

If mold does occur:

  • If possible, have a sample identified by a mycologist
  • Take the precautions advised by an industrial hygienist, according to the identification of the mold. Wear the recommended personal protection equipment (PPE) including respirator or mask, gloves, goggles, Tyvek suits and hair coverings.
  • Isolate affected objects – physically separate into another space and remove
  • Ensure the air handling system in the infected space is isolated from the rest of the building
  • Once the affected specimens or objects are dry, remove the mold deposit with a HEPA (High Efficiency Particulate Apparatus) vacuum on low suction. Use only a HEPA vacuum, which captures even very small particles such as mold spores and prevents them from being spread through the vacuum’s exhaust system.
  • Keep the object(s) in a dry environment

Soot and Fire Residues

If there is a fire, shut down the ventilation systems and close internal doors to prevent the spread of smoke and soot if you can do so without danger to yourself. Personal safety first!

Once you are allowed back into the space, open any external doors and windows to exhaust smoke. Use exhaust fans and consider turning your HVAC system to 100% fresh air intake.

Collections that have been exposed to a fire may be highly compromised. Their integrity and appearance may be altered and they may be extremely fragile, especially if they are also wet. Damage caused by extremely high temperatures is irreversible.

Soot may contain hazardous substances including lead, arsenic, PCB’s, etc., according to what burned. As with mold, have the deposited soot analyzed, and take the advice of an industrial hygienist on correct handling and appropriate PPE before starting a cleaning program. Generally, nitrile or rubber gloves, a properly fitted respirator or mask, goggles and disposable coveralls will be recommended. If highly toxic substances are present, it may be a requirement that qualified HAZMAT professionals carry out the cleaning operation under the guidance of collections staff.

General rules for soot removal:

  • Get started as soon as possible
    • The longer soot stays on the surface, the harder it is to remove
    • Some soot is acidic and can degrade museum materials.
  • Prioritize cleaning sooty objects
  • Porous surfaces and/or intricate surfaces
  • Objects with charred areas and structural damage
  • Organic materials
  • More sooty to less sooty
  • Try not to touch sooty objects directly - handle as little as because handling ingrains the soot particles into the pores
  • Soot is so fine that it will get into every crack and onto every surface. Be prepared to clean everything that was exposed.

Soot removal methods:

  • Dry methods are preferred to anything involving water or solvents.
    • First, vacuum on-site with a HEPA vacuum using micro attachments and soft brushes
    • Follow the vacuuming with dry brushing, “soot sponges”, or kneaded erasers


Odors can linger and be very annoying. Smokey odors will dissipate over time, but can be reduced during the early stages of the recovery by the removal of the damaged collections and building materials. Some odors can be prevented simply by not allow the objects to become exposed. For example, the odor of mold can be prevented by quickly freezing the damaged collections to prevent mold growth.

After that, plenty of fresh air circulation will help. Do not use ozone as

it will degrade cellulose and other materials. However, specimens or artifacts may be placed in an enclosure with zeolites (molecular traps), which will absorb odors.


Mud is a residue often associated with receding flood waters, as layers of levigated silt will be deposited over the surface of your artifacts and storage equipment. The composition of this water-bore sediment will vary according to its origins, and may contain toxic substances – sewage, pathogens, pesticides, and other chemicals. If this is the case, take the precautions recommended by an industrial hygienist.

When mud is allowed to dry on specimens, it becomes hard, and may be very difficult to remove. Therefore, if you have time and resources immediately after an event, the following is recommended:

  • If objects are wet and muddy, and will tolerate the flow of water to remove mud, items may be gently rinsed. Use a series of three or four tubs of cool rinse water.
  • Mud can be rinsed off wet books. Hold books closed so that the mud will not infiltrate the text block.
  • If mud has dried, it may be possible to use a brush or vacuum to gently remove it. Use using a plastic screen between the nozzle and the object to protect the object.

If you cannot deal with mud while the collection is still wet, remember that many artifacts or specimens can be frozen and dealt with at a later time (see “Freezing”).

Additional References and Resources 

Extensive resources are available on the Museum SOS Response & Salvage webpage

Rossol, Monona.Mold, Nothing to Sneeze At. Arts, Crafts & Theater Safety, Inc. (ACTS) 1997 (revised 3/5/01)

Spafford-Ricci, Sarah, and F. Graham. 2000. The fire at the Royal Saskatchewan Museum, parts I and II. JAIC 39 (15-36) and (37-56).

Nyberg, Sandra. The Invasion of the Giant Spore. (SOLINET) Preservation Program Leaflet No. 5 Atlanta: Southeastern Library Network, 1987.

Access the list of preservation supply vendors who sell some of the materials mentioned here.