A wash is a term for a visual arts technique resulting in a semi-transparent layer of colour.
Historically associated with the four arts of the scholar-officials, the technique was often applied to landscapes in traditional Chinese, Japanese, and Korean painting.
The result is a smooth and uniform area that ideally lacks the appearance of brush strokes and is semi-transparent.
However, when gum arabic watercolor washes are applied to a highly absorbent surface, such as paper, the effects are long lasting.
[2] In ceramics, a wash is typically a coloring oxide thinned with water applied to the piece to achieve an effect similar to a glaze.