The company at which I am employed produces split rings that are used in the manufacture of fishing tackle. The rings are used to attach hooks to lures. We are looking for a way to apply a color finish to these rings which are durable enough to withstand the conditions which they must endure.
The ring sizes range from .165 to .670 inch diameter. We usually nickel or zinc plate these rings based on our customer's requirements and some of our customers have been inquiring about colored split rings to attach to their products.
I have dyed and lacquered some of our zinc plated rings, but that proved to be unacceptable. The color doesn’t hold up very well in outdoor conditions. What we need is a method to color several thousand split rings at a time with a durable finish with very few, if any, imperfections.
Epoxy paints will adhere to clean zinc surfaces. On the other hand, adhesion to nickel plating could be a problem. As I understand it, plated nickel is deposited in platelets with spaces in between much like those between floor tiles. Corrosion occurs in these spaces causing poor adhesion. The longer the period between plating and painting, the poorer the adhesion of organic coatings. The best way to solve the adhesion problem is to coat as soon as possible after nickel plating. Short of that, sanding and light abrasive blasting is indicated. Again, an epoxy will be your best bet. Now, how to paint them.
Large numbers of small parts can be dip-spin painted. The Products Finishing 2003 Directory and Technology Guide lists suppliers of Painting Equipment, Dip-spin Painting and suppliers of Painting Equipment, centrifugal, on page 405. Suppliers of coatings for this method are listed under Chemical Coatings on pages 320 and 321 in the same Directory.