Applied to painting media, the term glazing means the laying of a transparent colour over previously laid and dried-out pigments, that may be opaque or transparent. With water-glazing only water need be added to the colours, with acrylics just the acrylic medium and water. For glazing with oil-paints, the diluent can be such as: linseed oil, poppy oil, turpentine or white spirit. Glazed colours appear to advance while opaque recede. Very rich translucent effects can be gained; for example, note the extreme richness of crimson in some of Titian's paintings, obtained by glazing over these areas with lake.