This month’s 1091 Project addresses that bane of every library and archives conservator: mold. Whether the mold is black, white, green, magenta, or yellow, it is all treated the same way: with caution and immediate action. The mold that we deal with in the lab comes from three main sources:
- newly acquired items for Special Collections and Archives which are valued highly enough to make dealing with mold worth the trouble;
- items returning from circulation which were not cared for properly by the borrowing patrons;
- mold outbreaks in the collection, which could be caused by a leaky roof or water pipe, or extreme humidity in situations when the HVAC breaks down.
The “sniff test” is a pretty reliable indicator of mold, but technician Mindy Moe rightly scolds me whenever she sees me lifting a suspect book to my nose. Mold spores, even if dormant, find the warm, moist environment of human nasal passages and lungs to be a cozy place to take up residence. Repeated exposure to mold can also lead to sensitivities and allergies which, in the most extreme cases, can induce life-threatening allergic reactions. So, we always take a little extra precaution when dealing with the fuzzy stuff. Mold can be identified by a visual inspection under magnification, especially under raking light. If a visual examination is inconclusive because the spores are in a dormant phase, or the spot is a residual stain, then the presence of mold can be confirmed by examining the item under UV light, which causes mold hyphae to fluoresce rather dramatically.
Mold hyphae fluorescing under UV light.
The minimum PPE (personal protective equipment) for dealing with mold includes glasses or goggles, a lab coat (and in general keeping as much skin covered as possible), latex or nitrile gloves, and a P95 or P100 disposable respirator.
PPE for mold mitigation.
Nilfisk HEPA vacuum for mold removal.
Once personal precautions have been taken, we act. In the case of situations 1 or 2 described above, we are usually dealing with just a few items at a time. The moldy items are first isolated from the rest of the collection, and then assessed for damage. In the case of circulating items which have been returned to the Library with significant mold damage, we usually discard the item entirely and charge the patron to replace it.
In the case of Special Collections and Archives materials, we keep the moldy items quarantined until they can be vacuumed under the fume hood with a special vacuum fitted with a HEPA filter. We try to minimize the amount of moldy items we accept because our staffing levels allow us only 1 to 2 hours per week on our “mold workflow.” Items which have been treated for mold are affixed with a small label saying so, along with the date. In part this is to inform patrons about a potential health risk, and in part this helps us keep track of which items might be making repeat visits to the lab.
Situation 3, a mold outbreak in the collection, is dealt with in a slightly different manner. In the case of an active mold outbreak, the first step is not only to isolate the affected materials as quickly as possible, but also, if possible, to make the active bloom go dormant. We wrap items loosely in waxed paper and put them in one of our conservation freezers. The low temperature and humidity in the freezer will cause the mold to go dormant within a few days. Once the infestation is dormant, the items can be removed from the freezer and vacuumed — and treated further, if necessary — in small, manageable batches.
Mold-infested collection materials in the freezer.
Meanwhile, the environmental conditions which caused the mold outbreak in the first place must be dealt with swiftly to prevent it from spreading throughout the collection. Leaking or standing water must be stopped and mopped up, while humidity and temperature levels must be brought into a safe range, and the ventilation checked. We also have a couple of portable HEPA vacuums for vacuuming mold on-site.
Portable 3M HEPA vacuum for mold.
In the case of a large mold outbreak affecting thousands of items, we would be too understaffed and under-equipped to cope, so we have vendor contracts in place to work with a professional recovery company under those circumstances.
Let’s head over to Preservation Underground to see how they feel about mold in the Duke University Libraries Conservation Department.