Like the Clear label stock, the Metallic material will affect how the colours look. Unlike with the Clear, light colours do not need to be avoided, but since the shiny metal surface will show through the lighter ink coverage, this will need to be considered in the final design. Again, if pictures are included in the design, they might not look as intended.
To address this, white ink can be printed first and the colour printed on top of it. Also, because the white does not need to cover the whole area and can be printed in select areas, striking contrasts between shiny and matte colours can be achieved. As with White Ink on Clear stock, extra inspections will be done on the files so that the desired effect is obtained.