Cold bluing question

tangara

I have a bolt on firearm accessory that came with bright plated screws and nuts. I was able to find black machine screws a a local hardware store but they did no have any black nuts. My question is does cold bluing take to shiny plated hardware or do I have to grind or file the plating off first. This was not a high dollar item and I do not want to spend more than a few bucks on it. The shiny hardware just looks wrong. I do have some cold bluing so that is not part of he cost.

charliemeyer007

Remove the plating. Multiple treatments on warm metal will help.

tangara

Kind of what I figured, Just thought I would ask. Thanks charlie.

truthful

Try this. It works pretty well on zinc or cadmium plated hardware.
Place the shiny item on a fire-proof solid metal surface such as the top of a bench vice. Now use a propane or butane torch to heat the part. First any oil or grease gets burned off. When the part gets hot enough you will see the shiny surface quickly dull as the zinc or cadmium oxidizes. Hold the flame on the part for a few seconds longer then let the part cool. Once cool, scrub it with a wet brush and let it dry. Then apply some cold blue. I have done this to "antique" various larger hardware items and see no reason it shouldn't work on small nuts as well.