It can be difficult to make a good copy of a Diazo original. Diazo originals have a changing lightness with a 'cloudy' background, which can give an unclear output. The plotWAVE T75 has a special [Diazo] preset, that follows the lightness and changing background of the original and copies to an even and high quality output.
Use the [Diazo] mode for originals that have a changing 'cloudy' background.
Dark and light Diazo originals, or other light or dark originals with a changing background can be copied in [Diazo] mode.