Labour relations at the plant were usually good; during the first two decades of the enterprise's existence the organisational structure was relatively simple, with limited hierarchies, and there were limited attempts at a benevolent social policy by the plant's management. Psychological testing of potential workers was gradually introduced, first for skilled workers, and after World War II for unskilled workers. Vocational training was slowly introduced after 1938. In the post-war period foreign workers from Italy, Spain, Turkey, Yugoslavia and Morocco began to be employed at the plant, and in the 1960s the practice of housing foreign workers in floating hotels was begun. Post-war there was no major industrial action until 1973, when 2,300 workers went on strike at the IJmuiden plant. During the Steel crisis there were no strikes, despite significant lay-offs.