This is an oxidized iron sheet on which there is numerous scratches and dents. Most of the scratches and pits corroded and are covered with rust. Besides, some of the rust is dripping down due to the rain wash.

It is a oxidized brushed aluminum plate with dirt. The oxidation reduces the reflectiveness of the metal, so the surface has uneven glossiness.

Besides oxidation, dirt also affects the colors and reflectivity of aluminum.

This highly oxidized metal plate is full of round cap nails, but well aligned. It is usually used as covers for containers.

Dirt has accumulated around round caps as those are good places to hide debris.

Oxidation has different degrees too. It can be proved by different reflectivity.

Of course, scratches cannot be omitted for oxidized iron metals.

It is a cobalt or nickel like metal plate. The surface has been hammered, so it is very uneven and bumpy. The surface is also oxidized affecting the reflection.