This is a treatment method often used to finish galvanizing, and is the most commonly used and inexpensive surface treatment among surface treatments (plating). Typically associated with a silver color, but in the case of hexavalent chromate, the color is golden, as if it were coated in 7 colors.Recently, due to RoHS and environmental concerns, trivalent chromate has become more popular. There are a wide variety of colors, including colored chromate and black chromate. Among the normal chromates, there are silver, bluish silver, green, red, yellow, etc. The appearance varies depending on the plating chemical and film thickness, so decorative plating is used. Instead, it is plated for rust prevention. It is also important to note that it is often mistaken for chrome plating.