Acrylic Retarder is used to counter the fast drying properties of acrylic paints making possible the usage of wet on wet or other techniques which would otherwise require oil paints. When used correctly, they can keep the paint from drying for half an hour extra to a full day's working time. Applying too much retardant, however, can prevent a layer from drying correctly for as long as the retardant is present, causing future damage to the painting unless the affected layer of paint is removed or re-mixed.