Where theworld gathers for metal finishing
Q&As since 1989
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Selecting a black finish for screws
Q. Hello, I'm looking for a finish on small screws that looks exactly like a black oxide or a black zinc (hex). The finish is mainly cosmetic, but corrosion resistance must be better than standard black zinc. I've tried one of the new trivalent black chromates on zinc, but the finish is not good enough.
Any suggestions?
Does not have to be plated finish, any finish that meets the requirements will do.
Thanks
plating - Montreal, Qc, Canada
2007
A. When you say "but the finish is not good enough", it would really help if we had a better clue as to what portion of the finish is not good enough.
You might look at one of the alloy-zinc with a black chromate. another possibility would be a black dye on regular zinc.
- Navarre, Florida
2007
A. What are your requirements?
Seems like: 1) RoHS compliant 2) Cosmetically attractive 3) Corrosion resistance to match hex black zinc.
That's tough! You might try your trivalent black in conjunction with a black dye, followed by a sealer. Or, you could shop around for a different tri black chromate.
Dave Wichern
Consultant - The Bronx, New York
2007
Q. Requirements are, 1, must be RoHS compliant, 2, appearance must be as good as a hex black or black oxide, the surface finish must not have any white spots or signs of abrasion like the ones I've seen in the tri blacks. 3, the corrosion resistance needs to be better than a black oxide (not zinc, there was an error in the original question.), but similar to a black zinc. The part is cosmetic and used indoors on consumer electronics.
All the tri blacks I have seen so far do not give the deep, rich black of a hex. They are also more prone to scratching.
What about zinc plating and then blackening the zinc? how does that finish look?
- Montreal, Qc, Canada
2007
A. If you can make your screws out of aluminum they can be black anodized. This would give you the black appearance and RoHS compliance with excellent corrosion resistance.
Jim GorsichCompton, California, USA
2007
A. Bulk e-coat might be an option, but it would depend on the size of the screw.
Adam Adkisson- McAllen, Texas
2007
Q. I design accessory sights for rifles and my company mass produces them. We are looking for ways to economize on some of our parts such as screws, e-clips, and pins, while still getting adequate corrosion-resistance. Most of the commonly available off the shelf parts are steel with black oxide, or they are raw stainless. The screws we use typically serve the purpose of either mounting or adjusting the sights, and the dowel pins serve the purpose of axle pins that get occasional use as the sights are flipped up or stowed. Any advice you could give would be appreciated along the lines of what seem like good options for blackening and corrosion protecting, while being most economical for application to the raw parts.
Thanks in advance.
designer - Austin, Texas, USA
May 18, 2013
A. Zinc Nickel Plating - Black is affordable and durable enough.
Khozem Vahaanwala
Saify Ind
Bengaluru, Karnataka, India
June 16, 2013
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