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Black anodizing is a special type of anodizing that produces black metal that often has benefits beyond normal anodizing. One way of dyeing the metal for black anodizing is to use inorganic salts made from metals that turn the metal black, and the second way is to use organic black dye; organic dye typically offers limited benefits. A major benefit of this anodizing is that black dye fares better in areas of high light and heat. The metal also tends to corrode much slower than metal that has been subjected to regular anodizing.
The easier, and less beneficial, black anodizing method is to use normal black dye. This is applied directly after the metal is anodized and, while the metal will receive more benefits than normally dyed anodized metals, the benefits will not be as powerful as the other method of anodizing. The dye does not change the structure of the anodized metal, so the benefits are limited and weaker than other black anodized metals.
While harder to do, the second method of black anodizing involves the use of metallic salts. These can be added after the anodizing process, which is the most common way, or they can be added during the anodizing process. Salts typically are needed to keep the anodizing process stable, but this type of anodizing will require the use of special blackening salts. The salts are capable of changing the metal’s structure, so the effects are much stronger when compared to metal blackened by dye.
Anodized metals typically are subjected to demanding and dangerous environments that have high heat and powerful light. While normal anodized metal can go through these environments rather well, black anodizing better prepares metal by allowing it to remain unscathed by the heat and light. This allows the anodized metal to be used for spacecrafts, optical devices that cannot afford the metal bleaching, and health care equipment that must withstand high heat and powerful cleaning chemicals.
Another benefit of using black anodizing is improved resistance to wear and corrosion. This occurs because of the sealant used to keep the black dye or salt bound to the metal, and because the black color forms a better barrier over the metal when compared to other colors. This means anodized metals are better in extreme conditions and do not corrode when used as semiconductors or other products that are constantly exposed to a high amount of electricity.