Category:Mold/Fungi

From Wiki

Introduction

Mold affects many different types of materials and heritage objects. Please consult the following pages for more information about mold-remediation, prevention of mold growth, and safety precautions when dealing with a mold infestation.

Image of the back cover of a pharmacist's prescription book that became moldy after being wet from Hurricane Sandy flooding in October 2012. Image taken by Rachael Perkins Arenstein and courtesy of the Irvington History Center.

Terminology

See the Lexicon pages for mold and mildew. The Paper Conservation Catalog also has a detailed Glossary of mold-related terminology.

Health and Safety

Identification

See: Identification on BPG wiki

Health effects

All molds can pose a health risk to humans. Adverse reactions to mold can be a mild skin irritation, or can be severe for those with compromised immune systems. Both dormant and active mold can cause an unsafe reaction.

Surface molds – the molds that conservators usually encounter – produce conidia, which form and release mold spores into the air. Those spores float through the air and land on surfaces along with dirt, skin cells, pollen, fibers, and other materials that make up dust.

One element found in molds is mycotoxins. A class of mycotoxins – known as trichothecenes – has been implicated as potentially infecting humans via inhalation rather than ingestion or dermal contact. One of the molds that produces this mycotoxin is Stachybotrys chartarum, named in the media as “toxic black mold.”

Protection

Always wear appropriate Personal Protective Equipment (PPE) in any situation where you might encounter mold; you cannot predict how you will react. PPE should include respiratory protection, as well as eye (impermeable goggles) and skin protection (gloves, lab coats, sleeve guards). Your respirator should have N-95 or P-100 filters for filtration of mold spores and activated charcoal filters if odors are a problem. Be sure to get your doctor’s permission before using a respirator (even disposable ones), especially if you have asthma or other respiratory issues. Be certain to be fit tested annually!

Mitigation

Cleaning is your best bet for preventing mold, especially when it’s dormant. Removing the spores doesn’t give them the chance to germinate and colonize.

For safe cleaning, be sure to use a HEPA or ULPA-filtered vacuum (variable suction is best) in a fume hood while wearing PPE. Dispose of mold-infested filters, vacuum bags, and other waste by sealing them in thick polyethylene bags and throwing them away with the trash.

What is the key element in stopping the mold life cycle? Water availability! Water vapor in the air, water content of the mold, and the equilibrium moisture content and its availability within the substrate all contribute to the life cycle of mold. Controlling your environment by keeping your dew point below 50ºF and your relative humidity below 65% will reduce the possibility of spore germination.

Mold spores are tough; with thick cell walls, mold spores are not defeated easily. Spores are designed to survive in an outdoor environment so that they do their job: breaking down dead organic matter such as fallen leaves and dead trees. Dormant conidia and spores can survive extreme heat, drought, and freezing temperatures.

Active, germinated spores are more susceptible to destruction. Flash or quick freezing around 32ºF (0ºC) kills active mold spores from the inside out: the moisture in the cytoplasm in the spore turns into ice crystals. As the water expands (freezes), it causes the active mold spore to burst, breaking up the cell wall. Dormant spores should be removed through cleaning (see #4).

The colored stains that you see on mold-infested objects are pigments excreted by the actively-growing hyphae of the fungus and/or the pigment in the hyphae that penetrate the substrate. Hyphae are the long, branch-like structures of a fungus that are its main mode of vegetative growth. The pigments are present to help protect the mold cells from radiation (IR, visible, and UV).

Resources

General facts about mold: how it forms, how it can adversely affect our health, and why it is difficult to eliminate.
Extensive article by a certified industrial hygienist about mold, its toxicology, evaluating mold presence and exposure assessment, remediation activities, and the effectiveness of decontamination.

Resources by Specialty Group

Book and Paper Materials

Electronic Materials

Photographic Materials

Textiles

Environmental Concerns for Textiles: Biological Attack

List of All Pages In This Category