AURUNA® 503 Rose Gold Electrolyte

Neutral, cadmium-free electrolyte for red layers

AURUNA® 503 is a neutral, cadmium-free gold-copper electrolyte for the deposition of bright red surfaces. It works without free cyanide.

AURUNA® 503 is especially suited to decorative but also technical applications, such as sliprings. Special features of this electrolyte are its long lifetime and fast deposition speed. For low-carat gold-saving layers, it also offers good resistance to corrosion and abrasion.

The gold-copper electrolyte can be used for rack and barrel plating and can achieve layers up to 5 μm in thickness.

Electrolyte characteristics

Electrolyte type


Metal content

6 (5 - 7) g/l Au
2.5 (2.0 - 3.0) g/l Cu

pH value

7.5 (7.3 - 7.8)

Operating temperature

65 (60 - 70) °C

Current density range

0.8 (0.6 - 1.2) A/dm²

Deposition rate

approx. 0.25 μm/min at 0.8 A/dm²

Anode material

Pt-Ti (type PLATINODE® Pt/Ti)

Coating characteristics


Gold Copper


75 wt.% Au
25 wt.% Cu

Colour of deposit

rose gold



Hardness of deposit

380 - 400 HV

Max. coating thickness

approx. 5 μm

Density of the coating

approx. 15 g/cm³


  • Gold-saving coating (approx. 18ct)
  • Long lifetime
  • Fast deposition speed
  • Cadmium-free
  • Red gold-copper coatings
  • Resistant to tarnishing and corrosion
  • Maximum layer thickness approx. 5 μm
  • Very hard (380 - 400 HV), abrasion-resistant
  • Suitable for rack and barrel


  • Accessories
  • Jewelry
  • Watches
  • Bathroom fittings
  • Lighting
  • Spectacle frames
  • Writing utensils
  • Sliprings
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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

Tel.: +49 (6181) 59 6005
Fax: +49 (6181) 59 2970

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.