Brother DCP-4020C - Manual (Page 81)

8 - 3 PRINTER DRIVER SETTINGS
Media Type
To achieve the best print results, the media being printed on should
be selected in the driver. The DCP changes the way it prints,
depending on the selected media type.
Plain Paper
Inkjet Paper
Glossy Paper (4 colour)
Glossy Paper (3 colour)
Transparencies
The print quality of black ink depends on the type of glossy
paper you are using. Black ink is used when you select Glossy
Paper (4 colour). If the glossy paper you are using repels the
black ink, select Glossy Paper (3 colour), which simulates black
ink by combining the three ink colours.