A chemical used to slow the drying rate of paint. Retarders were commonly used in the nineteenth century for wet-in-wet techniques. Examples of retarders for linseed oil paints are clove oil, spike oil, lavender oil, rosemary oil and poppy seed oil. Butyl lactate has been used as a retarder for industrial lacquers. Synonyms: Inhibitor. Museum of Fine Arts, Boston (2000). [J. Cassar, R. de Angelis]