Lacquered saya are sensitive to two environmental factors: direct UV exposure and rapid humidity fluctuation. UV light causes lacquer pigments to fade and can make the finish brittle over time, so display cases with UV-filtering glass or wall positions away from direct sunlight are strongly preferred. Humidity swings - especially in climates where heated indoor air becomes very dry in winter - cause the wood beneath the lacquer to expand and contract, eventually lifting or cracking the finish at seams and along the koiguchi opening. Storing or displaying the saya in a room maintained between 40-60% relative humidity eliminates most of this risk. If the saya will be stored rather than displayed, wrapping it loosely in acid-free tissue inside a wooden or cardboard box (not airtight plastic) allows the wood to breathe while protecting the surface from dust and accidental contact.