Preparing for and Cleaning Mold on Paper Records

 If you have ever stepped into your records room and caught the unmistakable scent of mildew or opened a drawer to find a fuzzy film growing there, you know the stress this can cause. You might feel that all hope is lost, but thankfully, you can often salvage moldy documents. A quick, informed response will ensure the preservation of your records and your safety.

Our Alabama heat and humidity works against us in preventing the growth of mold. In high temperatures, mold can begin to grow on wet paper in less than 48 hours. This means taking precautions like not storing records under a water pipe; keeping temperatures below 70°F; or if the relative humidity in your storage area rises over 65% using a dehumidifier to stabilize the RH can go a long way in preventing water damage and mitigating mold growth. (Turn off the dehumidifier once the relative humidity is holding steady between 40% and 64%. Low humidity comes with its own issues!) No matter how many precautions you take, however, the chance of water damage to your records is never zero. Pipes can leak, hurricanes can batter your town, or cut grass can clog a drain causing flooding. The possibility of damage from water means an opportunity for mold, but your organization can prepare now so that you are ready to respond immediately. 

This blog will walk you through the basics of identifying and responding to moldy paper records and cleaning them using the safest, most effective mold removal method, a HEPA vacuum cleaner. For more in-depth resources and a list of disaster response vendors, please visit this page:

Safety First! 

When working around mold, remember that human safety and health is the number one priority. Mold exposure can cause allergic reactions that include, but are not limited to, a runny nose, itchy watery eyes, skin rashes, and aggravation of asthma. If anyone is immunocompromised, they should not handle mold or work in the contaminated area as they are more likely to have a severe reaction. If the mold damage is extreme, the amount of moldy materials is extensive, there is not enough staff available, or if the building itself is infected, you will need to work with an outside disaster response vendor rather than dealing with the issue yourself. If you assess the situation and are confident that you can safely deal with the moldy materials, you can move forward with in-house remediation.

You must have personal protective equipment on hand before you can even begin to assess the situation. It is good practice to put together a disaster kit ahead of time and make sure that all employees know where it is stored. Personal protective equipment includes aprons, lab coats, or disposable hazard suits, disposable gloves (nitrile is best), and masks that are approved for use with mold. Masks should be fit-tested to ensure proper protection and a good seal when worn correctly. Disposable masks approved for mold include N-95, R-95, and P-95. Custom-fitted respirators with particulate cartridges are also an option if dealing with moldy materials is likely to be an ongoing task. Goggles or glasses will provide protection for your eyes.  Having a disaster kit that includes these items will allow you to respond rapidly to a mold outbreak.

Active Mold

Active Mold, Inactive Mold, and Things That Aren’t Mold 

An “earthy” or musty smell may be your first clue that there is a mold outbreak in your records, but this smell is not always present. Touch and sight are your most essential senses when identifying mold and assessing whether it is active or not.


  • Can feel wet (You can tell this through gloves. Don’t touch the mold!)
  • Will smear when touched
  • Often has a white furry appearance around the edges

Active mold spreads quickly and is more likely to cause respiratory symptoms. The most important thing to remember is you cannot clean active mold!  Attempting to clean active mold can transfer the spores and cause another outbreak. 


  • Feels powdery or dry (You still have those gloves on, correct?)
  • Does not smear when touched

Inactive mold is not dead. It is dormant. Subjected to the proper environmental conditions (Alabama’s hot, humid climate), the mold will reactivate. 

Not Mold

Sometimes, harmless blemishes appear on records and are mistaken as mold. Foxing is characterized by reddish-brown spots, which are caused by the oxidation of metals left in the paper from the paper making process. You might also come across efflorescence, white crystals which occur from salt dissolved by humidity. While these may be startling if discovered, they are harmless to your records, and cleaning is unnecessary. 

Efflorescence on Books
Foxing on a map of south-central Tennessee

Responding to, Deactivating, and Cleaning Mold

Your goal is to isolate affected items and work to deactivate the mold as quickly as possible. 


With a small outbreak, move the individual items to a clean area with lower humidity. DO NOT place items in plastic bags or sealed bins! Plastic creates a microclimate that allows mold growth to flourish. Remember, our Alabama climate is already helping the mold grow. It does not need additional help from you.

If the outbreak is large and moving the collection is impractical, seal off a room from the rest of the building as best as possible. Humidity in the isolated area must be below 55% to stop most mold growth. You may need dehumidifiers to achieve this humidity. Reduce the temperature to under 70°F. Adding circulating air will help to dry out wet documents, floor and desk fans are an inexpensive option. The fans can also help to prevent further mold growth in the future. The documents must dry out so that the mold goes dormant and becomes powdery. If the humidity and temperature remain low enough, after two days, the mold may have gone dormant, and you can commence with cleaning.

The shelving or drawer housing the records should be cleaned with alcohol (70% isopropyl alcohol or ethanol) and allowed to fully dry before anything is returned to the location. Placing alcohol and cloths in your disaster kit for this purpose is a great idea. If the records were stored in boxes, the boxes should not be reused. You will need to order new boxes.

Air Drying

Air drying your moldy items to deactivate the mold is a cost-effective option if you have a small number of items and the weather is cooperative. Mold can be deactivated at temperatures between 86°F and 104°F.  If it is not windy outside, place items on a clean sheet or piece of paper in direct sunlight for no more than an hour. If the item is a book with mold issues on more than one page you will need to periodically turn the pages. Refrain from leaving records out in the sun longer than an hour, you don’t want to bleach them out!


If you cannot deal with the moldy items within 48hrs after the active mold was first noted, or the isolation didn’t shock the mold into submission, you should freeze the items. You may also choose to freeze items with inactive mold that has been around for a while if you won’t be able to clean it in a timely manner, this will keep the mold from reactivating. You should not however plan to keep the items in the freezer indefinitely. Make a plan to address these items as soon as you possibly can. Wrap the individual objects in freezer paper. Label and date each item. This makes identification easier when removing documents from the freezer. Items should be frozen for at least 48 hours and must defrost before proceeding with cleaning. The defrost period will take a minimum of several hours. You do not want to shock the item by moving it from the freezer to high temperatures too quickly.  

Do not freeze wet photographs, leather-bound books, vellum, or audio-visual materials. You should contact a disaster response vendor for these items as they are more fragile to deal with.

You should not use your fridge’s freezer, but you also do not need to invest in a specialty freezer like a scientific freezer. A household upright frost-free freezer can be a great cost-effective choice for short term remediation projects. Chest freezers are also acceptable. You will want to make sure that the freezer can keep a constant temperature. Plan on monitoring the temperature inside of the freezer at least every other day while the items are in the freezer. There are several resources available online that describe different freezers acceptable for freezing records. This Conserve O Gram from the National Park Service gives specifications you should look for. If you regularly work with paper that may have mold spores, your institution may think about investing in a freezer specifically for this purpose. You may also consider an agreement with another institution to use their freezer in case you need to freeze moldy items. 


Working in a sheltered area outside is preferable, but when vacuuming mold indoors, work in a well-ventilated area to clean the items. If you have access to one, use a fume hood. Working in front of a window with a fan that draws the air outside is also a safer option.

You will need a HEPA vacuum, preferably with a multiple speed function, to remove inactive mold, and you should wear a mask and gloves during the entire cleaning project. HEPA (high efficiency particulate air) filters capture more than 99.97% of .3 or larger microns. Mold spores are typically between 3 and 40 microns. Vacuums with a HEPA filter are often more costly than regular vacuums but you don’t need to purchase a museum grade vacuum. You can find vacuums from brands like BLACK+DECKER and Dyson which have HEPA filters and are much more affordable. A universal micro tool kit for your vacuum would be helpful as the smaller tools provide a smaller suction source; the kit is especially necessary if cleaning volumes. These tools should be dedicated solely to mold remediation to avoid the spread of mold spores. Storing the tools in your disaster kit is a smart idea. Do not attempt to vacuum records if they have pastel or charcoal drawings or flaking paint. 

While vacuuming, use the lowest suction available (this is why a multi speed function is useful) and avoid direct contact with the paper as this can cause damage or weaken the paper. Instead, hover the suction source right over the paper while holding the paper down with a gloved hand or covered weights. You can use a soft bristle brush to loosen the mold while you vacuum if necessary. Fragile records should be vacuumed through a mesh or window screen frame. In the absence of a frame, you can completely cover the nozzle with cheesecloth to avoid vacuuming up scraps or pieces of the paper.

Bound volumes with mold may be trickier to clean than single sheets of paper, so a soft bristle brush is a necessary tool. If mold is worked into the pages or caught in the spine of a volume, use the bristle brush to loosen the dried mold. Always work outwards from the spine and make sure not to catch the edge of the pages. Records that have sustained mold damage will never return to their original appearance despite cleaning, especially if they have gone through the drying and freezing process. They will, however, be usable.

It is important to clean all tools after you’ve completed the cleaning project. You can clean the micro tools and brushes in a 1:1 ratio solution of bleach and water. Wipe down your vacuum in the same solution. Make sure that the tools are entirely dry before returning them to your disaster kit. If the soft bristles brushes are especially dirty or damaged from cleaning, you may make the decision to discard them and purchase new brushes for your disaster kit.

Removing Mold Odor

While not always present in an outbreak, the smell may linger on documents even after you have thoroughly cleaned the mold from your records. There is a chance that you can deal with this smell in-house using a makeshift neutralization chamber. You will need a large sealable bin and a smaller bin that will fit inside of the larger one. In the bottom of the larger bin, pour baking soda, kitty litter or plain charcoal (BBQ briquettes). The charcoal, litter or baking soda will act as the neutralizing agent. Place records in the smaller bin. You do not want the documents to come into contact with the smell neutralizer at any time! Place the smaller bin inside of the larger and place the large lid on the bin. Monitor the materials in the chamber every few days to see if the odor has dissipated or not; it may take a while for the smell to disappear. If the smell does not dissipate or is from a large volume of records, you should contact a disaster response vendor.

So your records are clean now what?

Once your documents are clean and ready to be refiled, ensure that any problems in the storage area have been addressed. If the cause of the mold was a broken pipe, it needs to be fixed, and flooring needs to be dried before returning the records. If a hurricane or tornado was the catalyst for the leak and mold outbreak, you might not be able to return the records to their original place at all. You will have to find another temporary or even permanent home for the records. Once you’ve returned the records to their shelf or drawer, you should create a schedule that allows you check on the records regularly.  It is best practice to check on all records, especially those stored offsite, at a minimum of every week so that you know if there are any facility problems, bug infestations, or mold outbreaks and respond quickly. Mold is scary, and in Alabama, we may not be able to avoid it. Having a disaster kit and a plan so that you can rapidly respond to an outbreak, however, can give you some peace of mind.

Records Management Archivist Hannah Marshall Bawden wrote this blog.

For further information on mold remediation, here are some resources:


Library of Congress: Collections Care

The National Archives: Archives and Mold

The National Park Service: Conserve O Grams

The Northeast Document Conservation Center (NEDCC): Preservation Leaflets


Carvalho, Catrina.  Portugal’s National Archives. 2018.

Picket, Clarence E. Letter from Clarence E. Pickett to Patricia and Priscilla Stephens, April 28, 1960. 1960-04-28. State Archives of Florida, Florida Memory.

Whiteway, Geoffrey. Mold. 2016.

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