Cleaning a museum seems to be everybody's work, because everybody cleans his own house from time to time. Yet in many large museums, a professional organization is hired for the job, whereas in smaller ones, often a group of volunteers takes care of cleaning duties. Their cleaning plan is based on standards derived from their work in schools and offices, as to cleaning equipment, cleansers, and velocity (300 m² per hour!). In exhibition and storage rooms, however, it is not the velocity that counts, but the personnel and the sensible use they make of cleansers and equipment. An open and frank communication between the museum employees and the cleaning agency, including instruction and correction when needed, the drawing up of rules, establishing mutual responsibilities, the attitude towards the cleaners, the types of equipment used, the frequency of cleaning certain objects and parts of the museum depending on the number of visitors, and the application of a special cleanser for showcase windows. Several examples are mentioned of objects that received damage due to exaggerated cleanliness.