Abstract: A method of diagnosing or determining parameters for an installation for detecting open defects in the surfaces of parts by sweating, the method including passing at least one standard testpiece through the installation, the testpiece having a surface possessing at least one pattern representative of the type of defect that is to be detected, applying to the surface of the testpiece a penetrating composition including an indicator substance, washing, drying, applying to the surface of the testpiece a composition including a developer, and illuminating the surface of the testpiece to illuminate any remaining indicator substance so as to form a developed image of the or each pattern and deduce therefrom an indication about the quality of the operation of the installation.

Abstract: Gas under pressure is admitted through an orifice formed in the bottom portion of a tank of substance in powder form, and is guided along an internal tube connected to the admission orifice, the tube passes through the powder stored in the tank and entrains powder through openings formed in the wall of the tube, the powder being extracted in the form of a gas-and-powder flow through an outlet at the top portion of the tank. The gas-and-powder mixture traveling along the internal tube is guided to the top portion of the tank where it is directed substantially towards a side wall of the tank so as to set up a gas-and-powder flow traveling through the volume situated in the tank above the powder stored in the tank, prior to the gas-and-powder flow being extracted through the outlet. The gas-and-powder flow can be taken to one or more powdering nozzles, e.g. in a system for powdering a developer in an installation for detecting surface defects by sweating.