A feature of the Artists' oil colors is their slow drying time. Even a slightly thicker coat of paint can extend drying time by several weeks. Too thick layers can also lead to cracking.
To avoid this - especially for underpainting and impasto work - Lukas offers a range of quality mediums which can be added to the color and so reduce the drying time. Some of these media also have an impact on the characteristics of the color.
There are also means of prolonging the drying time, to keep the color open and workable.