Final answer:
A glaze is a popular technique in oil painting where a thin, transparent film of color is painted over an existing surface.
Step-by-step explanation:
The popular technique in oil painting, where a transparent film of color is painted over an already-painted surface, is called a glaze. A glaze is typically a thin, translucent layer of paint that is applied to modify the colors and tones of an underlying layer of paint. It adds depth and richness to the overall composition.
Learn more about Oil painting techniques