Winsor & Newton Water Colour Blending Medium slows the drying of water colours, allowing more time for blending. It is particularly useful in hot climates where artists would like their water colours to stay open and workable for longer periods of time. For maximum effect dilute with medium only. Can also be mixed with water. Blending Medium can be used in a number of different ways. For maximum blending time, mix the medium directly with the water colour. Alternatively, you can apply the medium directly to the paper in preparation for the water colour wash. Dilution with water will provide a variety of lending / drying times. Drying rates will vary and depend on the temperature and air flow. Once dry, further washes can be applied over any washes which included Blending Medium.