Using the procedural Scratches texture is a great way to add weathering and wear to materials, and to metal materials in particular. These are the settings available for the Scratches procedural.
Color
Set the color of the scratches. In cases where the texture is used for opacity maps set this to black.
Background
The color between the scratches.
Scale
Use this to set the overall scale of the scratch pattern generated.
Bump Height
Increase this value to obtain deeper scratches. It can also be set to a negative value to obtain very subtle scratches.
Density
Use this to control the number of scratches generated.
Size
Use this to set the size of the individual scratches. Expand to control the scratch thinness (width) and falloff (fade).
Directional Noise
This controls the randomness of the direction of the scratches. Decrease this value to have scratches in a more aligned direction. Expand to choose Direction Field mapping.
Noise
Controls the straightness of the scratches. Increase the value to have more irregular scratches. Expand to access the Noise Scale slider.
Levels
Controls the number of unique scratches that are generated. Expand to access the level scale.