Sometimes the touch up paint looks too dark, especially for metallic colors.

The orientation of the flakes of metal (or ceramic in the case of pearl finishes) can affect the final finish. When metallic or pearl finish paints are sprayed, these flakes are consistently aligned and the finish reflects light accordingly. When such paints are brushed on, these flakes can lay in the paint differently, causing less light to be reflected. When less light is reflected, the paint appears darker. We recommend that you apply another coat. Try to brush this coat on lightly. Then apply clear coat. The control coat should help reduce this dark effect.

Aerosols and Control Coats
When spraying metallic colors, the same concept applies. The final coat is called a "control coat" or "drop coat", and it is applied differently to get the metallic particles to lay down in alignment. Typically, the control coat is sprayed from further away, with less paint, by moving the can faster than a normal coat. The result is a light dusting of the last coat, which allows those metallic flakes to lay down properly to achieve the metallic effect.