Linseed oil is the fastest drying of all the drying oils (such as safflower, poppy seed and walnut oil), it has excellent adhesion properties and it dries to a glossy, flexible film. For these reasons, linseed oil is the most commonly used binder in commercially made oil paints and it makes an excellent medium for extending oil paints. A linseed oil medium will increase gloss, loosen stiff tube colours and allow you to control the transparency of the paint for techniques such as glazing. By no means do you need to use linseed oil, you can use oil paints straight from the tube or use an alternative drying oil as a medium. Diluting oil paint too much with artist solvents, such as turpentine or mineral spirits, is not recommended because it weakens the paint film. An oil medium, whether linseed oil or not, is preferable because it extends the paint without under-binding it.