How to Finish Black Oxide Metal

By Debbie Tolle
Finished black oxide metal
and overgrown garden and wrought iron railings image by Stephen Gibson from

Black oxide is used on metals that are prone to rust. It is particularly applied to steel and iron, but is also used on other metals. You can apply black oxide to most metals that you have at your home to stop or prevent rusting, such as metal sheds, posts and wrought iron. Preparation is the key for the successful bonding process of black oxide to metal and the final finish coat.

Applying Black Oxide

Wire brush the surface of your metal to remove any flaking paint or rust buildup. A wire brush will quickly scrape off all loose particles. Follow the wire brushing by using steel wool to sand the surface of your metal as smooth as possible.

Use a slightly damp cloth to remove sanding dust, dirt and grime from the surface of the metal. Water from a slightly damp cloth will quickly evaporate while you are wiping down your metal and not cause problems with the black oxide.

Thoroughly stir black oxide, then with a paint brush or roller apply an even coat over the entire metal surface. Do not apply black oxide too heavily or it will run.

Allow the black oxide to dry for a maximum of 24 hours or by the recommended amount of time required by the manufacturer. When black oxide is completely dry the surface of the metal, including rust, will turn black. Apply a second coat to any areas that you may have missed and let it dry. Follow the application of black oxide with a cover coat of paint.

Finishing Black Oxide

Apply a coat of exterior, oil-based primer made for metals, to provide a strong bonding surface for a cover coat of paint. Using a primer will prolong the life of your paint. Thoroughly wash your paintbrush with paint thinner. You cannot use water to clean a paintbrush used in oil-based products.

Wait for the primer to dry before you apply a cover coat. Some primers will completely dry within two hours. Read the label on the primer, and follow the manufacturer's requirements before you paint.

Paint the surface of your primed black oxide metal with direct-to-metal paint. Use a paintbrush for areas that you cannot access with a roller. On larger areas, use a foam roller. A foam roller will make the metal look as if it has been sprayed. Allow your cover coat to dry, then apply a second coat if necessary.

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