The glacis is a technique of wall decoration which allows to obtain numerous nuances and transitions of colours among which in matching tones (the same tint in several nuances), the contrast (opposition of colours) and the cameo (association of a dominant tint in nearby tints)

The glacis must not be confused(merged) with the term "washing", what is generally made. They are two very different techniques. The glacis serves for unifying a zone when the ombre/éclairci contrast is too strong or when the demarcations between two tones are too much cut. It is in a sense the application of a transparent coat(layer) of colour on another pigment.

The glacis is a technique of deposit(warehouse) of the colours which consists in diluting the painting in a very important way (1 flight(theft). Of painting for 5 in 6 flight(theft). Of water) the painting so applied is going to create a quasi-transparent coat(layer) which qualifies acutely the previous colours. We can also mix him(it) with the medium to give him(her) a slightly more plastic aspect and avoid that she(it) goes to hollows as an ink.