Absorption of moisture by various instrument materials during 24‐h storage, under high humidity is considered. Glass, copper, stainless steel, and nickel absorbed −2, chromium and clean brass −2, and tarnished brass and polytetrafluoroethylene approximately 10 mg dm−2. Silicone rubber, natural rubber, and neoprene absorbed 30, 123, and 217 mg dm−2, respectively.