Mould & Water-Damaged Books - What Everyone Needs to Know

Have you ever found a favourite book or important file mottled with stains and musty odours after a water leak or flood? The hidden threat of mould is more destructive than most realise. Water doesn’t just warp and blur pages—it creates the perfect conditions for fungi to invade and ruin cherished collections. 

The Sneaky Power of Mould

When books, documents, or paperwork get wet, filamentous fungi like Aspergillus, Penicillium, Cladosporium, Chaetomium, Trichoderma, Stachybotrys, and Alternaria can colonise the fibres in as little as 24–28 hours. They release acids and enzymes that eat away at paper, create permanent stains, and produce strong, unpleasant odours. But it’s not just about the damage—mould spores are a real health risk, especially for allergy and asthma sufferers. 

Why Water Damage Is Worse Than Fire

Many expect fire to be a library’s worst enemy, but water “damages books more surely than fire”. Even minor leaks or humidity spikes can trigger long-term chemical, mechanical, and aesthetic decay. Every part of a book and its binding can support fungal growth, and once mould takes hold, the effects can linger invisibly in collections and air quality. 

How Mould Takes Hold—and How Fast

Mould spores are everywhere—in library air, carpets, ventilation ducts, and even in dust. They can stay dormant for years until they meet moisture, sparking rapid germination and colony growth. Xerophilic species thrive on just a little dampness, while dangerous black-spored fungi like Stachybotrys chartarum require heavier flooding. The longer books stay damp, the deeper the contamination sets in. 

What Happens to Paper, Inks & Bindings?

• Foxing: Small reddish or yellowish stains linked to fungal metabolites and chemical reactions.

• Structural Decay: Fungi digest cellulose and glue, weakening pages and causing binding distortion.

• Pigment & Odour: Mould can leave coloured stains and strong, persistent musty smells.

It's not just about appearance—fungi can continue to break down materials even without visible growth if enzymatic activity is retained, especially after freeze-drying. 

Mould Risk = Health Risk

Mould in libraries and offices isn’t just a property concern. Exposure to airborne spores has proven links to respiratory conditions, allergic reactions, asthma, and, in rare cases, mycotoxicosis. Individuals with sensitivities or weakened immune systems should avoid contaminated environments and always use protective gear during clean-ups. 

How to Respond: Expert Assessment Is Key

Water damage? Act quickly! Here’s why consulting Biological Health Services and Dr Cameron Jones, PhD can help:

• Rapid Lab Testing: Identify mould species, contamination level, and health risks.

• Evidence-Based Remediation: Recommendations for freezing, drying, and safe handling matched to local regulations and the value of the collection.

• Prevention Plans: Recommendations for air quality management, humidity control, and ongoing monitoring to ensure long-term protection.

Proven Strategies to Rescue Collections

• Immediate Freezing grants time for decision-making and preservation. 

• Vacuum Freeze-Drying is ideal for rare and valuable books with heavy water damage, minimising ink run and page stickiness.

• Physical & Chemical Decontamination may involve biocides, UV-gamma radiation, or ethanol vapour—but must be handled by experts to avoid further damage or health risks.

• Digitisation: For materials too fragile to conserve, digitisation ensures access and information preservation. 

How Biological Health Services Can Help

As experienced mycologists and consultants, Biological Health Services offers:

• On-site and remote inspections for libraries, archives, offices, and home collections

• Mould identification reports and full documentation for insurance and restoration

• Custom remediation recommendations and health risk evaluation

If water damage strikes, don’t hesitate—connect with Dr Cameron Jones, PhD and Biological Health Services. Mould may be small, but the stakes for health, heritage, and valuable collections are immense.

Need an expert’s opinion or a lab test in Australia? Contact Biological Health Services today to protect your books and paperwork from hidden mould risks.

REFERENCE:

El Jaddaoui, I.; Denda, K.; Ghazal, H.; Bennett, J.W. Drenched Pages: A Primer on Wet Books. Biology 2025, 14, 911. https://doi.org/ 10.3390/biology14080911