Definition: Mildew is a type of fungus that typically thrives in warm, damp, or humid environments. It often appears as a powdery, fuzzy, or patchy film on surfaces and can cause discoloration, staining, or degradation of organic materials such as paper, canvas, mats, and backing boards.

Overview

Mildew is one of the most common biological threats to artwork and framed materials, especially in poorly ventilated areas. It is distinct from mold in its appearance and growth pattern, but both are fungal contaminants that can compromise the longevity and aesthetics of artwork.

Causes

High Humidity: Relative humidity above 60-65% encourages fungal growth.
Poor Airflow: Stagnant or unventilated environments trap moisture against art surfaces.
Direct Water Exposure: Leaks, floods, or condensation on glazing or backing boards can lead to mildew formation.
Organic Materials: Paper, canvas, wood, and cotton mats provide nutrients for fungal growth.

Prevention

Maintain a controlled environment with relative humidity between 40-50%.
Ensure proper ventilation and air circulation around framed artwork.
Use archival, acid-free, and lignin-free materials to reduce food sources for fungi.
Regularly inspect and clean areas prone to moisture accumulation.

Damage Caused

Staining or discoloration on paper, canvas, or mat surfaces.
Weakening of fibers in paper or textile-based artwork.
Potential permanent damage if left untreated for extended periods.

Treatment

Consult a professional conservator for valuable artwork.
Remove and isolate affected materials to prevent spread.
Use gentle cleaning techniques such as soft brushes or dry cleaning sponges; avoid excessive moisture.

Mildew