Decay of leather binding may be most effectively delayed by which condition?

• A. Air conditioning
• B. Exposure to direct sunlight
• C. High humidity
• D. Frequent handling without support

Answer: (A)

Leather bindings deteriorate most when environmental conditions change—heat, moisture, light, and pollutants all drive chemical and physical damage. Keeping the library environment stable with air conditioning helps maintain consistent temperature and relative humidity, which slows the chemical reactions in leather (like hydrolysis and oxidation) and reduces swelling, drying, mold growth, and dust buildup. In short, a controlled climate slows multiple decay pathways at once.

Direct sunlight speeds up fading and embrittlement due to UV exposure, so it accelerates damage. Very high humidity promotes mold and salt crystallization, causing staining and weakening. Handling without proper support causes physical wear, mis-shaping, and oils from skin to affect the surface. Among these options, climate control via air conditioning best delays decay because it tackles the most pervasive cause—environmental fluctuation—while the others introduce specific, more rapid damage.