Nickel has a shiny appearance and produces a slightly yellowish reflection in daylight. The nickel layer offers very thorough protection against corrosion but is not chip-proof. After some time, a nickel layer will form a grey sheen (as is the case with coins). Even though nickel can be used as a finishing layer, it is more often applied as the bearing layer for the finishing decorative layer.
For superior protection against corrosion, the nickel layer must isolate the ground material from the atmosphere entirely, which means it must be pore-tight. This requires a nickel layer of at least 20 µm, depending on the underlying material and the product’s use. In some cases, the layer must be 40 to 50 µm. For restorations we only apply a double nickel layer of 50 µm using the duplex system.
With the duplex system, the product is firstly plated with a semi-bright nickel layer for corrosion protection. On top of that, a bright nickel layer is applied for a decorative appearance. The pores of both layers do not link up entirely and both layers also have a different level of preciousness, which gives the product extra protection against corrosion.
The nickel layer can be applied in a matte, semi-gloss or high-gloss finish. A product with a matte or semi-bright nickel layer can be subsequently chrome-plated. With decorative chrome-plating, the nickel layer determines the shine.