MIRALLOY® For Costume Jewellery

Copper-tin-(zinc) electrolytes as nickel-free alternatives

MIRALLOY® has been offering alternative nickel-free plating for fashion jewellery since 1981. With MIRALLOY®, electrolytes are used to deposit copper-tin or copper-tin(-zinc) coatings in rack and barrel plating. Depending on the electrolyte used, white or yellow layers can be deposited.

MIRALLOY® coatings stand out due to their excellent distribution of metal and, depending on the bath type, high tarnish resistance, levelling, abrasion resistance and exceptional corrosion resistance. A further plating layer with gold, rhodium, palladium or other precious metals, as well as tarnish protection if required, can be added with the right pre-treatment to create optimal corrosion protection.

Electrolyte characteristics

Electrolyte type

Alkaline-cyanide

Metal content

10.5 g/l Cu
21.5 g/l Sn
1.6 g/l Zn

pH value

Alkaline

Operating temperature

60 °C

Current density range

0.5 A/dm²

Plating speed

Approx. 0.12 μm/ min at 0.5 A/dm²

Anode material

MMO (type PLATINODE® 167)

Coating characteristics

Coating

Copper-tin-zinc

Alloy composition

85 wt. % Cu
10 wt. % Sn
5 wt. % Zn

Colour of deposit

2 N

Brightness

Bright

Hardness

400 HV

Max. coating thickness

20 μm

Density of the coating

8.4 g/cm³

Advantages

  • Copper-tin-(zinc) alloy coatings of white or yellow colour
  • Diamagnetic
  • Nickel-free (§27 of REACH, Ann. XVII, Reg. (EC) No 1907/2006, Standard 100 by OEKO-Tex®)
  • Resistant to tarnishing and corrosion
  • Excellent layer thickness distribution
  • Can be lacquered
  • Can be combined with precious metals
  • Tried and tested process does not cause allergic reactions in the way that nickel does

Applications

  • Costume jewellery
  • Ear studs / earrings
  • Necklaces
  • Bangles
  • Wrist watches

MIRALLOY® Copper-Tin-(Zinc) Electrolytes for Costume Jewellery:

  • MIRALLOY® 2840 (white) for rack operation
  • MIRALLOY® 2841 (white) for rack and barrel operation
  • MIRALLOY® 2844 (white) for barrel and rack operation
  • MIRALLOY® 2847 (1N and 2N) for barrel and rack operation
  • MIRALLOY® 2850 (white) for rack and barrel operation

European Nickel Regulation
In Europe 15 to 20 per cent of all women and about five percent of all men are allergic to nickel. For this reason, legislators issued the 7th change to the Consumer Goods Act; the European Nickel Act (§27, Ann. XVII, Reg. (EC) No 1907/2006): Earrings and comparable objects remaining in a wound during the healing process may not contain more than 0.5 % by weight of nickel.

Objects intended to come into direct and prolonged contact with the skin (e. g. earrings, necklaces, rings, watches, buttons etc.) were not permitted if the part of the product that would come into prolonged contact with the skin released more than 0.5 µg/cm²/week of nickel.

When using nickel-free plating, it must be guaranteed that the part of the product that will be in direct and prolonged contact with the skin does not release more than 0.5 µg/cm²/week of nickel in two years under normal circumstances.

Definition of Prolonged Skin Contact (ECHA Q&A no935)
The ECHA (European Chemical Agency) developed a scientifically supported interpretation of 'prolonged skin contact':
Prolonged contact with the skin is defined as potential content between the skin and items containing nickel for more than

  • 10 minutes for three or more occasions within two weeks, or
  • 30 minutes for one or more occasions within two weeks.

Apart from custome jewellery, this regulation affects a number of consumer goods such as clothing accessories, craft tools, writing utensils, spectacle frames, work tools, buckles, handles and steering wheels, devices for body care, mouthpieces, kitchen appliances and electronic devices.

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Questions about the product?

Markus Legeler

+49 7171 607 204

For inquiries and additional information
please contact

Umicore AG & Co. KG
Rodenbacher Chaussee 4
63457 Hanau-Wolfgang
Germany

Tel.: +49 (6181) 59 6005
Fax: +49 (6181) 59 2970
Email: chemistry@umicore.com
Website: www.chemistry.umicore.com

The information and statements contained herein are provided free of charge. They are believed to be accurate at the time of publication, but Umicore makes no warranty with respect thereto, including but not limited to any results to be obtained or the infringement of any proprietary rights. Use or application of such information or statements is at the user´s sole discretion, without any liability on the part of Umicore. Nothing herein shall be construed as a license or recommendation for use, which infringes upon any proprietary rights. All sales are subject to Umicore´s General Conditions of Sale and Delivery.