Are black bolts painted black?

Black BoltMost likely no. Our “black” bolts are unfinished or bare steel. The term “black bolt” is an industry term for plain finish or no finish bolts. These bolts offer no corrosion resistance and will rust over time. If you are looking for a decorative coating that is actually black, you will want to specify that they are actually coated and state which kind of coating is necessary. You will want to contact your local plating company or powder coater for the many different options from black oxide, black zinc, powder coating or even just painting to get the look you are after. Portland Bolt typically does not offer these finishes since we do not perform these services within our facility.

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    @Hani- The iron in the steel oxidizes when exposed to moisture and creates iron oxide which in layman’s terms is rust.

    I have a Sub-Contractor on-site using mainly A325 mechanically galvanized hardware with wax coated nuts, but have some A490 Black bolts for some of their connections, after reviewing the MTR’s, im not seeing any kind of lubrication noted. Are there instances where black bolts have been lubricated or are they generally just “raw”?

    @Jason- Normally, black A490 bolts are sold as plain, with an oily finish. Additional lubricant can be added, but it is not standard.

    I wondering how the bolt become black? What is the chemical reaction? Or is it from heat treatments effect? I get some problem to make bolt become black.. sometimes it becomes red-black..

    @Figo- There are a few methods for turning the bolt black, from a black oxide conversion coating, to an oil darkening process, to some sort of black coating, paint, etc. You would need to discuss the specifics with your processor, we are not familiar enough with your specific situation to properly diagnose any problems you are having.

    Hello. We are experiencing some difficulties with our supplier of bolts. After 5 years of delivering the bolts (5,000,000 pcs) they are talking about shelf life of bolts. They claim that shelf life is 6 months because the bolts do not have any coating. Is there any law in USA obligating manufacturer to state expiry date on the label and required storage condition for shelf life items? This is urgent. If you can provide any kind of information regarding above, we would be grateful.
    Thank you.

    @Jelena- There is no “shelf life” of bolts. Steel bolts do not have any inherent degrading that occurs, so they can theoretically remain on the shelf for years as long as they are kept dry. However, if they are not in a controlled environment, and are allowed to corrode due to weather conditions, then they will eventually corrode to a point where they should not be used. That corrosion point will vary based on the material, environment, etc.

    In black coating bolt we found rust corrosion then what we need to do for corrosion its acceptable or rejected please give feedback its urgent

    @Mohammed- Rejection based on corrosion is subjective will be up to the project engineer. We are unable to make recommendations in this case.

    @Paul- Apologies but we don’t typically deal in small screws like that. Your local fastener distributor or hardware store should be able to help you with these.

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