Mold on Books and Paper

The snow storm in February 2021 caught central Texas by surprise and created a lot of hardship. Burst pipes were among the many challenges. I received a number of inquiries from people dealing with paper materials that got wet in their homes. I’d like to offer some basic information about what you can do with wet or moldy books and documents and when you should contact a professional to help.

Mold can grow on almost any material, but we will focus here on paper-based items: books, documents, and photographs. When paper materials become wet, from a weather-related incident or leaky pipes, mold growth begins fairly quickly, within 2 to 3 days. It’s important to address the wet items as soon as possible. Quick intervention to dry the materials will prevent serious damage. Note that mold growth is not limited to floods and leak events. Materials stored in even slightly damp environments, such as basements and garages, are in danger of mold growth. 

Handling paper materials after a flood or leak

If you find your papers damp or sitting in water, you first need to determine what kind of water it is. If it is “black water,” meaning toxic water, you should not handle the materials. A salvage professional should help with the cleanup, in this case. If you know the water to be safe and relatively clean, you can take the following steps to save your books and documents.

Sheets of wet paper spread out to dry. Photo by Sarah Norris

Sheets of wet paper spread out to dry. Photo by Sarah Norris.

Damp papers and photos: Gently separate stacked sheets while they are still wet, and lay them out to dry in a single layer. Remember that paper is easily torn when wet. Place them on butcher paper, towels, or paper towels. Exchange the towels frequently to aide in drying. Don’t lay towels on the image side of photographs, as it will likely stick. If the papers and photos do not separate from each other easily, don’t tug them apart, that will either tear the paper or damage the media. If the sheets are stuck together, take a deep breath, and let them dry. Once dry, they can likely be separated safely by a professional.

Photographs hung up to dry.

Another way to dry your photos is to hang them on a line with a wooden clothespin. Be sure the clothespin stays at the edge of the photo, not on the fragile image. Photo by Sarah Norris.

A book splayed open for drying, with paper towels inserted.

Damp books: For wet books, stand them up on their bottom edge, using supports if needed. Don’t use supports that will trap the water or prevent drying. Fan the pages open as best you can to allow the inside of the book to dry. Insert butcher paper or paper towels between numerous pages. Then change out the towels and shift the inserts to different openings as the book dries. Again, don’t tug apart stuck pages or they might tear.

Place a fan nearby your drying materials, but be careful that the fan isn’t tearing the papers or blowing them across the room.

If mold has already begun to grow, you will need the assistance of a paper conservator or mold remediation expert familiar with paper-based materials. Breathing mold can cause health problems, so do not handle moldy items or try to clean them without assistance. Do not use chemical agents to kill mold on paper. They are not designed for this use and the paper and media cannot tolerate them. A professional has methods for removing mold from paper without causing further damage and without breathing the mold.

Prevention!

Mold remediation can be difficult and time-consuming. Once paper has mold growth, it may never be entirely free of mold. Paper is a web of fibers, and mold grows both on the surface and into the fiber web. We can remove some of the mold, but tiny spores, trapped between fibers, may not be accessible. Paper-based materials that have been treated for mold should be stored in conditions where mold cannot grow. An item that had mold in the past should not be stored in potentially damp areas for any period of time, because the remaining spores can be quickly reactivated.

So, prevention is the priority when it comes to protecting books, documents, and photos from mold. In libraries and archives, we store collections according to strict standards: Temperatures are kept below 70 degrees Fahrenheit and relative humidity is kept at 55% +/- 5%. These conditions are ideal, but may not be realistic in a Texas home. I usually tell people that paper items are comfortable in the same conditions that make you comfortable inside your house or apartment. Keep your important items in the climatized parts of your home. Don’t store them in a garage, attic, or basement, not even temporarily. Storage boxes of papers should be raised off the floor. The most common mold damage I have seen is when papers were stored in a cardboard box, directly on a garage floor. Even a small amount of water can seep into the bottom of the box and dampen the items inside. A bedroom closet shelf works well for storage.

Be aware that perimeter walls in a home can be damp. Items stored next to a perimeter wall can be vulnerable. When I was in college, I lived in a finished basement apartment in Massachusetts. My books were on open-backed shelves along the wall. Many of the books grew mold on their fore-edge and I didn’t even know it. I occasionally get calls from people in Galveston and other high-humidity cities, reporting mold on the back of framed artworks that were hanging on a wall. Dampness is not always obvious.

Know your valuable items

You can make a list of the valuable paper-based materials you are storing in your home. Once a year, pull these items out of storage and check the condition. Are they clean and dry? Is the storage location still the best option for these papers?

If you need to speak with a conservator about storage options or other conservation needs, the American Institute for Conservation provides a search tool to locate conservators in your area. https://www.culturalheritage.org/

Preservation information provided by the Texas State Library and Archives Commission is intended only as a general guideline for collections care. The Texas State Library and Archives Commission is not responsible for any damage that might occur in the specific application of this information.