A method for the artificial weathering or light fastness testing of samples, comprising the steps of a. Providing a weathering chamber containing a UV radiation device with UV light emitting diodes (UV-LED) (31.n) of different emission bands; b. Placing at least one sample in the weathering chamber at a distance from the UV LEDs (31.n); c. Irradiating the sample with radiation from at least one UV LED (31.n) of a particular emission band; d. Analysing the changes in the sample due to the irradiation; and e. Performing steps c. and d. with one or more UV LEDs (31.n) of one or more further emission bands; wherein an apparatus is used for carrying out the method, which has a weathering chamber in which a UV radiation device is arranged, and in which at least one sample can be arranged in a sample plane spaced from the UV radiation device, wherein the UV radiation device contains a plurality of UV light-emitting diodes (UV LEDs) (31.n) containing three or more classes of UV LEDs (31.n) of different emission bands which are selected spectrally in such a way that a spectral distribution is obtained in the sample plane with which the rising edge of the UV component of the solar spectrum is simulated, wherein the UV LEDs (31.n) are combined in groups of 3 or more UV LEDs (31.n) each, wherein the groups are formed identically, and wherein the groups are spatially regularly distributed on a flat surface and arranged separately from one another, and at least one UV LED (31.n) from each of the different emission bands is represented in each group, and wherein the distance of the UV LEDs (31.n) from one another within a group is determined as an average value of the centre point distances of in each case directly adjacent UV LEDs (31.n) and this distance is smaller than the distance between the UV radiation device and the sample plane. a. Providing a weathering chamber containing a UV radiation device with UV light emitting diodes (UV-LED) (31.n) of different emission bands; b. Placing at least one sample in the weathering chamber at a distance from the UV LEDs (31.n); c. Irradiating the sample with radiation from at least one UV LED (31.n) of a particular emission band; d. Analysing the changes in the sample due to the irradiation; and e. Performing steps c. and d. with one or more UV LEDs (31.n) of one or more further emission bands; wherein an apparatus is used for carrying out the method, which has a weathering chamber in which a UV radiation device is arranged, and in which at least one sample can be arranged in a sample plane spaced from the UV radiation device, wherein the UV radiation device contains a plurality of UV light-emitting diodes (UV LEDs) (31.n) containing three or more classes of UV LEDs (31.n) of different emission bands which are selected spectrally in such a way that a spectral distribution is obtained in the sample plane with which the rising edge of the UV component of the solar spectrum is simulated, wherein the UV LEDs (31.n) are combined in groups of 3 or more UV LEDs (31.n) each, wherein the groups are formed identically, and wherein the groups are spatially regularly distributed on a flat surface and arranged separately from one another, and at least one UV LED (31.n) from each of the different emission bands is represented in each group, and wherein the distance of the UV LEDs (31.n) from one another within a group is determined as an average value of the centre point distances of in each case directly adjacent UV LEDs (31.n) and this distance is smaller than the distance between the UV radiation device and the sample plane. an apparatus is used for carrying out the method, which has a weathering chamber in which a UV radiation device is arranged, and in which at least one sample can be arranged in a sample plane spaced from the UV radiation device, wherein the UV radiation device contains a plurality of UV light-emitting diodes (UV LEDs) (31.n) containing three or more classes of UV LEDs (31.n) of different emission bands which are selected spectrally in such a way that a spectral distribution is obtained in the sample plane with which the rising edge of the UV component of the solar spectrum is simulated, wherein the UV LEDs (31.n) are combined in groups of 3 or more UV LEDs (31.n) each, wherein the groups are formed identically, and wherein the groups are spatially regularly distributed on a flat surface and arranged separately from one another, and at least one UV LED (31.n) from each of the different emission bands is represented in each group, and wherein the distance of the UV LEDs (31.n) from one another within a group is determined as an average value of the centre point distances of in each case directly adjacent UV LEDs (31.n) and this distance is smaller than the distance between the UV radiation device and the sample plane.