Trivalent Chrome Plating Processes

There are two methods for plating chrome from a trivalent solution, Sulfate and Chloride. Each has their own advantages and disadvantages:

Sulfate based process - Advantages
  • The color of the deposit is closer to hexavalent chrome
  • The process is very tolerant of metallic contamination
  • The process is comparatively simple to operate
  • Ion exchange is recommended for consistent performance in both corrosion and color
  • Operating temperature of the solution is ~65C meaning you do not need to bail out solution to compensate for additions
  • Chemical purification is possible as well as dummy plating

Sulfate based process - Disadvantages
  • The anode material is made of Iridium coated Titanium. This makes the cost of anodes expensive compared to chloride based processes

Chloride based process - Advantages
  • Comparatively easy to operate
  • Anode material is pure graphite making the anode costs comparatively cheap compared to sulfate based processes

Chloride based process - Disadvantages
  • Color is different to hexavalent chrome deposits, sulfate based processes are much closer
  • Temperature is ~25-35C so solution has to be removed if large additions are made to the bath