Lacquerwork consists of artefacts made of wood or another material which have been coated with Japanese lacquer, the hardened sap from the lacquer tree (Rhus verniciflua). The paint is applied in many thin layers, each layer having to dry before the next is added. The sap can be mixed with various pigments.
Lacquer artefacts are stored at the museum in a room with a special climate. The most important thing is that the relative humidity stays at 55-60%. Otherwise there's a risk that the wood will shrink without the lacquer coating following, and it may flake off.
Really skilfully lacquerwork handles differences in humidity better because the wood is impregnated with the same substances contained in the paint, and the wood has been able to absorb these substances over a long time.
As a precaution, the museum keeps all lacquered items at a constant relative humidity, and it's required that this climate be maintained during, for example, loans and transportation.