Polish monetary reform in 1957–58 prompted the NBP to test several alloys before settling on aluminum for the lower denominations. This piece is a trial strike — produced not for circulation but to evaluate die quality, metal flow, and striking pressure. The oak leaf design had already appeared on the circulating brass 1 złoty of 1949, making this an exercise in material substitution rather than design development. Fischer and Parchimowicz catalog it under separate references precisely because aluminum and brass trials from this period were struck on different planchet specifications and distributed to different evaluators.
Polish monetary reform in 1957–58 prompted the NBP to test several alloys before settling on aluminum for the lower denominations. This piece is a trial strike — produced not for circulation but to evaluate die quality, metal flow, and striking pressure. The oak leaf design had already appeared on the circulating brass 1 złoty of 1949, making this an exercise in material substitution rather than design development. Fischer and Parchimowicz catalog it under separate references precisely because aluminum and brass trials from this period were struck on different planchet specifications and distributed to different evaluators.