i e treated with the same surfactant containing solution were each fixed tension free in two holders of a testing device and arranged one on top of the other so that the surfaces of the cuvettes came to lie plane parallel in the abrasion test the holder for the upper cuvette is designed to be stationary the holder for the lower cuvette is arranged on a horizontally movable sample table during the abrasion test the upper cuvette was lowered onto the lower cuvette and a test force of 20 n was generated from an estimate of the practical loading appearance of scratches can be expected from a force of ca 1 n for the sample table on which the lower cuvette had been arranged a travel path of ca 10 mm was set and the upper cuvette was traversed by the lower cuvette in one direction twice with a test force of 20 n the friction traces thereby generated on the surfaces of the upper and the lower cuvette were examined by light microscopy and the increased scratch resistance and resulting improved wear resistance compared to uncoated cuvettes was assessed by the investigator it was observed that layered smeared areas with extensive diffusion resulted on the surface of the upper stationary cuvette due to the.