The decimal coins are minted in copper-plated steel (previously bronze), nickel-plated steel, cupronickel and nickel-brass. In modern German, Kupfernickel or Kupfer-Nickel designates the alloy cupronickel. Currently, cupronickel and nickel silver remain the basic material for silver-plated cutlery. Only cupronickel and modern multi-ply plated steel five-cent pieces are considered "circulation coins". Copper and its alloys (brasses, bronzes, cupronickel, copper-nickel-zinc, and others) are natural antimicrobial materials. The "silver" is cupronickel, 75% copper and 25% nickel. The 1 kroon was struck in cupronickel, the others in aluminum-bronze. This panic would lead to the demonetisation of the Korean cupronickel coinage in November 1908. In the past, true silver coins were debased with cupronickel. In 1972, cupronickel 5 baht coins were introduced, switching to cupronickel-clad copper in 1977. Another common modern use of cupronickel is silver-coloured coins. Copper was eliminated completely, replaced by cupronickel. A staggering amount of 266.480,000 of cupronickel coins were exchanged during this panic. The 1 and 2 toea were minted in bronze, with the others in cupronickel. Cupronickel 5-sen coins were introduced in 1889.