What is black optical Coating and what is it used for?

Metal parts can be provided with an improved matte black appearance with the help of black conversion coatings. The process of converting material to another state occurs by using an electrochemical or chemical reaction.

For black optical coating, a chemical reaction would take place after immersing parts in a solution of alkaline aqueous salts. The process usually occurs at a temperature of approximately 285 degrees Fahrenheit.

A compound called magnetite is created when the iron in the ferrous metal alloy reacts with the iron in the oxide bath. A layer of magnetite resides on the component’s surface to impart its finish.

A black optical coating finish improves both the appearance and dimensional stability of parts. Radiation-sensitive parts must also reduce light reflection on the surface.

The thickness of steel increases when you black coat it. The increase might only be insignificant, but it helps sharpen tools like screwdrivers and drills.

Processes involved in black Optical coating

There are various ways to blacken a surface. Here are the three main methods for black optical coating. Read below to find out how each process works;

Hot Bath

This process converts the surface material of fasteners into magnetite by treating them with different chemicals. The fasteners are dipped in one or more tanks and occasionally placed in water to complete the process.

Upon completion of the dipping process, the fastener’s top layer becomes porous and is then coated in oil. Rust is further retarded by the oil seeping into the material.

Cold Coating

During this process, a copper selenium compound is applied to the fasteners at room temperature. The application of this process does not require any chemicals or heat temperatures, making it more convenient to use in-house. If oil or wax is applied first, this form of oxidation becomes stronger than the other types.

Mid-Temperature Bath

As effective as the hot bath treatment method, but produces fewer toxic fumes. Surfaces are converted to magnetite at much lower temperatures than those found in the hot bath treatment method. Similarly, the hot bath method also meets the same military standards.

What are the advantages of black optical coating used for products & why?

Longevity is one advantage. As opposed to other materials, they do not rust or corrode. Water is the main cause of rusting, so their wax coatings protect them against it. These wax coatings also make cleaning a lot easier.

It doesn’t take as much time to clean the item because the wax prevents harmful substances from reaching the metalcore. In addition to giving your tools a sharper edge, the black optical coating will not dull over time. This means that you can be more certain about the quality of your products.

Some Benefits Of Black Optical coating

  • Fasteners do not significantly change in size as compared to hot-dip galvanizing.
  • An inexpensive alternative to electroplating and other methods of corrosion resistance.
  • Shine without being overpowering.
  • It is usually cheaper and faster to produce smaller sizes when done in large quantities.
  • Adds an oil finish to reduce galling risk
  • Finishing touches
  • Protects from mild corrosion and abrasion
  • The black coating adheres well to paint if you need to paint it


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