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Black Oxide Fasteners
Black Oxide Screws, Bolts, Nuts and Washers in Stainless Steel
Looking for Black Stainless Steel Hardware? Black Oxide Fasteners made from stainless steel, (usually grades 18-8 or 304) have been chemically treated to alter certain qualities of the material, most notably the color. The treatment also adds a mild corrosion and abrasion resistance (in addition to the plain stainless steel’s nature), and reduces the now black oxide stainless steel fastener’s reflective properties. To achieve maximum corrosion and abrasion resistance, the black oxide may be wax coated or oiled. Wax coated product is more dull, where as oil sealed product is spun off to remove excess oil and may be bright or shiny. Wax coating complies with military specifications as a Class 4 finish. Black residue may come off of these fasteners, so they should be wiped down before being applied in applications such as jewelry or finishes where they may come in contact with hands.
Black stainless steel hardware that has been treated in this manner is commonly used in the automotive industry on both car and motorcycle builds. Black Oxide Screws, Bolts and Nuts are also commonly used on dirt-bikes, 4 x 4's, ATV's and other off road vehicles, as well as in racking systems for automobiles including roof racks, grills and luggage or general gear racks. Additionally, this type of stainless fastener finish is often used in gun and knife builds, particularly in the handles, because of its corrosion and abrasion resistant qualities. Of course, black oxide fasteners are also used for their sleek black look as well.
Check out more information on Black Oxide as well as the other materials we offer.
Understanding the Black Oxide Process
Understanding The Black Oxide Process Transcript
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Bob: Hey, welcome back to Albany County Fasteners, Fasteners 101. I'm bob and today we're going to talk about the black oxide process. So let's get started.
Black Oxide. What is it? Black oxide is a conversion coating formed by an alkaline-salt solution. There are two processes in black oxide: you have a hot process and a cold process. The cold process does not meet government or milspec and will have color variations.
There are four different classes with black oxide. Black oxide has classes 1 through 4. The typical ones being used are classes 1 and 4, for fasteners. Class 1 basically runs between 285 degrees and 290 degrees as the processes baked. Class 4, which is for stainless steel, is a 250-degree process.
So what I have here presently right now are fasteners that had been black oxidized from stainless. These are all stainless parts that have been sent out and had the black oxide process applied. Some of these parts have different finishes, as far as how dark they're pigment is versus others.
The flat washers, as you can see here, have some minor scratches or imperfections and washers are not always going to be totally one hundred percent black. You can see some variations in some of them. Some will be purely black. I've seen them both ways. Sometimes we send them back for reprocessing. It's just the nature of the process that you have to deal with, like this socket cap screw.
I've seen this time and time again. I have two here: I have a larger one and a smaller one. The smaller one is a little darker than the larger one. The larger ones almost have more like a pigmented gun finish and with that process you can have different patinas on them. It's all a matter of how they process and how long they put it through the process to complete it and for some of these the typical process for black oxide is: rinse, black oxidize, rinse again, finish coat. That's the typical finish.
We stock a lot of black oxide products. A couple of products here that can be done, that we don't have here presently, are nylon lock nuts. They have a nylon part in those and they need to be protected before they go through the process so it does not change the physical condition of the nylon so it locks the nut in place.
I want to go through the five basic steps for black oxide which are clean, rinse, black oxidize, rinse again, supplementary finish. The supplementary finish is what protects the black oxide for a long, long time.
The coatings are oil, wax, paint, or lacquer. So dependent upon your condition and what you're applying this to, that will change how you finish your black oxide. So this particular one, this button head, has wax on it. This was put in wax, spun, and finished. The typical process for black oxide is black oxidize and then oil, spun off. That is the typical when someone does not specify.
So oil finish will give you a glossy finish. Wax finish will give you a matte finish. Paint or lacquer will give you a satin finish or a glossy finish dependent upon what you specify. It all depends on what you want your black oxide to be. We can send your product out if you want us to and have it done to your specifications.
Black oxide on stainless will yield excellent corrosion protection primarily due to their inherited properties. So when you black oxidize stainless chances are it's going to be more resistant to corrosion. Now keep in mind that a black oxide finish with oil in a saltwater condition will eventually show some type of rust. Same thing if you put black oxide on your car or your truck and you drive the vehicle in salt on the streets, you will see corrosion on the fasteners.
So you're going to want to coat your black oxide accordingly, and that's really what it comes down to.
We have a customer who sells his product that he puts our fasteners into and with those fasteners he first has them black oxidized. Then he sends them out to be painted black and then he lacquers it. So when it goes into a saltwater environment he will not experience, or his customer will not experience, any rust. Or another way to prevent rust would be to black oxidize 316 stainless. That should, you know, finish it but 316 is very expensive, it's not cheap, so you have to pay for that.
As far as hot and cold finish go, these are all done in hot black oxide. Cold finish, how you can tell is, cold will start to rub off. You can take your hand and you can rub it and the black oxide will rub off.
This will not rub off. So the hot process is the best process. Cold process will chip, it will scrape, you will have issues as far as black oxide goes in a cold finish.
Colors will change if you're using black oxide and a 900 degree or higher environment. So if you're going to put the black oxide parts into nine hundred, one thousand degrees, you're going to see variations in the color happen as it's in that environment.
If you're going to have your parts black oxidized and your parts are rusty or scaling, you will need to have the parts clean before they can be black oxidized. In other words it would have to go into an acid pickle to clean the parts and then rinse them back off again and then go through the process of black oxide.
Plated parts such as alloy with zinc plating on it or alloy with hot-dip galvanized plating-all those platings would have to be removed prior to black oxidizing. Black oxide only works on alloy or stainless steel products that are free of any other foreign products on it. So no oils, no grease, no platings, it's got to be clean parts.
Plating can be done to direct alloy parts or stainless steel parts series 18-8, 300, and 400 series. Anything other than that, a 316 or other special stainlesses, will need to be reviewed for how dark you're plating will be as far as-or your black oxide process.
Welding black oxide does not produce noxious fumes or hamper the ease which parts can be welded.
So in closing of black oxide, this is a process that many gun dealers, knife, and car products use this type of hardware in their applications.
It's an awesome look; people love it. We stock loads of this stuff and we also send out custom orders for processing.