At the end of 1950 it was decided that a new 5-crown coin would be added to the Czechoslovak monetary system. This was to replace the banknote of the same denomination. At the beginning of 1951, the Kremnica mint began experimenting with previously unused materials to replace the so-called coloured metals. This was necessary as these coloured metals had become much needed for the post-war reconstruction of the country and for industry. In addition to experimenting with PVC (polyvinyl chloride), which proved to be unsuitable, the mint’s employees also tried duralumin (an aluminium-copper alloy). The advantage of using this material was that it was a remnant material from the aerospace industry and stocks were in surplus. This fact also contributed to the decision of the Ministry of Finance to use duralumin as a potentially suitable material for the new 5-crown coin. Despite the mint’s objections, the Ministry commissioned patterns strikes of the coin.
The mint used Otto Gutfreund’s original design from 1925 for the new post-war 5-crown coin, with one minor difference, namely that the new pattern strike did not include the abbreviation “Kč” (meaning “Czech crown”) on the reverse. In the post-war period, the abbreviation “Kčs” (“Czechoslovak crown”) was established, which would not have fit into the original design. In addition to the design of the 5-crown coin, the mint also sent the Ministry of Finance patterns strikes in duralumin in the denominations of 20 hellers, 50 hellers and 1 crown (koruna). In the end, duralumin coins never entered circulation. The main reason for this was most likely the currency reform, which had been prepared in secret. There are even speculations that the design of the 5-crown coin was intended to divert attention away from the preparation of the monetary reform.