In these styles of work I apply the paint to the reverse side of perspex.
Layering colour the image builds depth and coverage but the first applications of paint will remain the most obvious - quite different to more traditional painting.
When complete the work is framed to be viewed from the unpainted, clean side.
I like to think of it that the hours of work are captured behind and that the careful colour selection is what the viewer is drawn to see.
I work with both matte and gloss perspex. The matte means an intentionally blurred finish.