A method is provided for detecting not fully set coatings and liquid or smearing impurities on a surface, in which in a first step a film is pressed onto a surface of a coating using a predefined press-on pressure, the film having a relative motion with respect to the surface of the coating, thereafter the film is pulled off the surface of the coating and finally it is determined whether impurities are adhering to the film. A device is also provided for performing the method, including at least one film, which may be pressed against a surface to be tested, at least one press-on roller having a surface by which the film is pressed against the coating, and at least one device for determining whether there are impurities adhering to the film.