The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Bronze Color Variation

I am having a very difficult time finding a plater that can consistently provide me with bronze plated parts that are consistent in color from batch-to-batch. What can I look for at the plater's facility that will ensure me that this supplier has the capability to provide me an acceptable level of color variation from shipment-to-shipment . . . so that my production line will remain running on a daily basis. Thanks, Ron

Ron Craddock
- Steeleville, Illinois, USA
1999

---

In a word, consistency. 10 percent tin gives a red color, 15 percent a gold color, so concentrations and temperatures must be held closely to minimize the composition differences. Further, such things as organics absorbed on the surface will affect the composition of the alloy, so you must give them consistent work and they must clean it consistently. Then too, the lacquer (assuming there is one) can be a variable.

If you are sending the plater consistent work, and everything is tightly controlled at the shop, he has at least a good shot at maintaining a color match.

If the shop evidences limited maintenance, poor housekeeping, lack of operator training, obvious price-shopping for chemicals, and general chaos, they'll produce inconsistent color. If the line and the operator function like a well-oiled machine, they have a very good chance of producing color-matched work for you.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
1999

As Ted points out consistency can be met with tight controls. I would probably start with a quality audit of the in house laboratory. A well equipped lab is a must for controlling bath chemistry, of this type of plating solution, to specified parameters. Ask to look at solution records and procedures. The shop that analyzes their solution more often will more than likely provide more consistent results. The other things to look for are purification schedules and filtration. A good all around quality audit can provide a wealth of information.

Rick Richardson, MSF
Dayton, Ohio
1999