Silver Plate on Reflectors

Question:

I am trying to silver plate stainless steel reflectors. The parts must have a high reflectivity. So far all of my attempts have resulted in peeling of the silver from the stainless steel. What am I doing wrong? S.F.

Answer:

You don’t mention in your e-mail how you are preparing the stainless steel, but I assume you are trying to plate directly on the stainless steel. That’s a no-no! Here is a procedure that should work:

1. Electropolish the stainless steel. The Metal Finishing Guidebook & Directory, 2000 edition, 904-333-2500, has a section describing the electropolishing process and formulas for stainless steel. This is a critical step in obtaining a surface with high reflectivity.
2. Activate cathodically in an alkaline cleaner.
3. Apply a Wood’s nickel strike.
4. Apply a silver strike.
5. Plate in a bright silver plating bath.
6. You may want to bright dip the silver plate after the plating step.
7. The last rinse step after the bright dip is to apply some type of tarnish preventive. Tarnish preventives based on benzotriazole or similar materials can be added to the final rinse. Suppliers can be found at www.pfonline.com in the Suppliers section under “Cleaning and Pretreatment” or in the Products Finishing Directory and Technology Guide, 2000 edition, 800-950-8020, under Tarnish-Preventive Treatments.

If you need help with any of the mentioned strike and plating baths contact your vendors.