Black Nickel / Ruthenium Plating Processes

Black Nickel

Camera exterior processed with Uyemura’s BlackNight deep black nickel finish

NIMUDEN™ BlackNight produces a deep black finish, with exceptional hardness and dense topography. This is an entirely new film “shape” with extraordinary micro-uniformity and corrosion resistance.

Recent developments in nickel overplates and co-deposited blackening agents have yielded a process that delivers both a dark black surface and very high hardness values. “BlackNight” has been adapted to use an electroless nickel rather than an electroplated nickel underlayer and overplate. This allows the plating of complex part geometries with a uniform nickel thickness.

The BlackNight process uses a standard EN underplate followed by a thin mid phos electroless Ni-P deposit layer. This thin 5 micron electroless Ni-P overplate is a lead-free ELV, WEE and RoHS-compliant layer that serves as both the seed layer and a topography matrix for the blackening deposit. A hardness of 600-80HV can be achieved.

Improved L values and low reflectance result from two factors: the deposited matrix that has been developed through use of a specific mid phos electroless Ni-P overplate, and a blackening agent electrolyte that uniformly etches, and deposits an Ni2O3-enriched surface.

Nickstar deposits a thin, highly uniform over-coat of black nickel-zinc alloy, preserving substrate brightness while producing a rich black nickel finish. The process is exceptionally versatile: A deposit thickness up to 2 microns can be achieved with rack or barrel. If a thicker deposit – or very high corrosion performance – is desired, a heavy nickel undercoat can be used.

Automotive interior features Uyemura’s BlackNight deep black nickel finish

Greater hardness can be achieved with a salt additive. Color density, from darkest black to softer hues, can be modified using a hull cell. Nickstar decorative black nickel can be dual-toned with UIC satin nickel for a distinctive and elegant finish.

Nickstar black nickel plating is well-suited for automotive interiors and for upscale sporting goods, where it diminishes glare and improves durability. It is also ideal for hardware, plumbing, architectural and other decorative uses that demand a luxurious finish with a long service life.

Nicostar uses the highly successful Nickstar chemistry as its base, and adds cobalt for enhanced hardness. Nicostar’s black nickel-cobalt-zinc alloy deposit preserves the brightness of the substrate. A nickel underplate can be used if enhanced corrosion protection is needed.


Ruthuna 479 Black strongly acidic ruthenium electrolyte is widely considered to be among the most attractive finishes. The process produces a deep, dark plated surface that closely resembles fine onyx. It seems to reflect and absorb light simultaneously. On large jewelry pieces, it is the perfect offset for gold. It is also an elegant finish for upscale eyewear.

Ruthuna is a trademark of Umicore GmbH and is available throughout North America exclusively from Uyemura.

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