ODOURLESS LEAN MEDIUM - This medium will be familiar to artists who have used and liked "Liquin". It is used for underpainting paint thinned with Liquid Gel, dries overnight and can be worked on the next day. It "tacks up" within hours for those who like working into a surface with "pull". It tends to retain brush marks, whereas Classic Medium is smooth. - 500ml - All these specialised Mediums are based on Alkyd Resins rather than Stand Oil or Linseed Oil so as to improve the drying characteristics and reduces the tendency to yellow. All these Mediums will maintain a similar degree of flexibility throughout the layers of a painting.