Metal finishing Q&As since 1989

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How do I color steel balls?

Hello, I'm looking for the best process to color steel balls that are a little over .5" in diameter. The surface finish I'm looking for would be similar to colored anodized aluminum. The ability to coat the balls in a full rainbow of colors would be preferred, but a process that can only produce a limited number of colors would be acceptable. The coating must be durable, scratch resistant, low cost and a suitable process for mass production. The problem that I'm foreseeing is how do you coat a small sphere evenly without the need for a fixture to hold the ball? I've also seen some surgical steel jewelry that has a nice iridescent coloring that would work, but I'm not sure what process was used. Any advice would be greatly appreciated!

Chris Schmidt
product development - Pleasanton, California, USA
2005

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Chris,

PVD coatings would meet your needs, if you were willing to stick with a very limited range of colors. You can get just about any shade of gold. Other colors include mauve (yes, mauve!), dark gray, light gray, and, of course, silver. All of these colors can be deposited with very high levels of consistency. There are techniques that can be used to produce a wider variety of colors, but batch to batch consistency is almost impossible, and the coatings are not nearly as wear resistant. It is possible to do it in large quantities at low cost -- we regularly coat cheap earring studs. What steel are you using? What's the annealing temperature? How tight are the tolerances?

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California
2005

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Hi Chris,

You could try running the balls in a dip/spin centrifuge coater, like something P. Ronci Machine in Rhode Island builds. A decent baked-on dyed coating should be durable enough if all you are looking for is scratch resistance.

Best regards

Jake Koch
G. J. Nikolas &Co.,Inc.

Bellwood, Illinois

2005