Revision Date: 4/03
Process Code: Navy/Marines: IND-006-99, IND-004-02; Air Force: MT05; Army: ELE
Usage List: Navy: Low; Marines: Low; Army: Low; Air Force: Low
Alternative For: Cyanide Silver Plating
Compliance Impact: Not applicable
Applicable EPCRA Targeted Constituents and CAS Numbers: Cyanide (CAS: 57-12-5)

Overview: Non-cyanide silver plating deposits a silver coating to production parts by dipping the parts in a bath solution, and rinsing. Using a non-cyanide plating process reduces the volume of hazardous waste generated and the associated disposal costs, and exposure of personnel to hazardous materials and wastes.

Until recently, the majority of silver plating of production parts has been accomplished using cyanide-based processes. The disadvantages of cyanide-based plating are that cyanides are hazardous to personnel, require frequent bath solution change-outs due to limited bath life, and the generation of rinse streams containing high concentrations of metals and cyanides. The rinse water generated requires pre-treatment to remove the cyanides and metals at the Industrial Wastewater Treatment Plant before the water can be released to the Public Owned Treatment Works (POTW). The treatment process at the treatment plant requires the use of toxic chemicals such as sulfuric acid, caustic, chlorine, and other hazardous materials.

Compliance Benefit: Chemicals used in cyanide-based silver processes are toxic to humans and are strictly regulated by local, state, and federal agencies. Using a non-cyanide process reduces the volume of hazardous waste and decreases the amount of cyanide at the facility. The reduction of hazardous waste helps facilities meet the requirements of waste reduction under RCRA, 40 CFR 262, Appendix. It may also help facilities reduce their generator status and lessen the amount of regulations (i.e., recordkeeping, reporting, inspections, transportation, accumulation time, emergency prevention and preparedness, emergency response) they are required to comply with under RCRA, 40 CFR 262. In addition, this technology allows facilities to eliminate cyanide bath solutions, so there is less chance that the facility would exceed the reporting thresholds for cyanide under SARA Title III (40 CFR 300, 355, 370, and 372; and EO 12856). Both process types may require an industrial wastewater discharge permit (local issue).

The compliance benefits listed here should be used as general guidelines and should not be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g., the amount of workload involved.

Materials Compatibility: The plating process can only be applied to metallic substrates.

Safety and Health: Caution must be exercised with the equipment. Proper personal protective equipment must be worn and other safety practices must be employed.

Consult your local industrial health specialist, your local health and safety personnel, and the appropriate MSDS prior to implementing this technology.

  • Elimination of cyanides, which results in reductions in worker exposure, and hence, reduced health risk and liability.
  • Reduction of costs and materials required for treating cyanide-contaminated rinse waters at wastewater treatment plants.
  • The removal of cyanides may enable the reclamation of metals from the bath solution and rinse water.
  • The same process equipment (tanks, heaters or coolant coils) that is currently used for cyanide silver processes can be used in the non-cyanide silver process.
  • The properties of adhesion, roughness, solderability, hydrogen embrittlement, throwing efficiency, torque tension, and fatigue life attained using the non-cyanide silver process were equal to or better than the cyanide silver deposit when deposited on copper substrates.

  • Not an acceptable alternative to the cyanide-base silver plating process for use on all parts due to failure to meet specific requirements. In particular, the process is unsuitable for nickel-plated parts, parts that have a tarnish resistance requirement, and parts that require a high thickness of silver deposit.
  • Silver deposit that is produced from the traditional cyanide silver process is of a higher visual quality than the non-cyanide process. In general, the non-cyanide silver deposits had a yellow color and a burnt appearance along the edges of the panels. This visual quality might be improved by experimentation with the racking of parts and the optimization of the process parameters of the solution.
  • Use of the non-cyanide bath with brighteners requires a higher degree of control than the non-cyanide bath without brighteners. Once the brighteners were added, the bath became unpredictable and more sensitive to changes in process conditions.

Economic Analysis: The National Defense Center for Environmental Excellence (NDCEE), operated by Concurrent Technologies Corporation (CTC), was tasked by the Department of Defense to investigate the technical viability of the non-cyanide silver process. No detailed economic analysis has been performed; however, the non-cyanide silver process can be implemented using existing tanks, heaters, and ventilation systems. The only cost variable will be for the initial make up for the process bath.

NSN/MSDS: None Identified.

Approving Authority: Appropriate authority for making process changes should always be sought and obtained prior to procuring or implementing any of the technologies identified herein.

Points of Contact: For more information

Vendors: This is not meant to be a complete list, as there may be other suppliers of this type of equipment.

Technic, Inc.
55 Maryland Ave
Pawtucket, RI 02860
Phone: (401) 728-7081

Sources: Concurrent Technologies Corporation. Non-Cyanide Silver Plating: Test Report. October 7, 1998.