Oil Medium - Liquin

Winsor & Newton Liquin is a fast-drying alkyd medium for oil painting that comes in five thicknesses for different effects.

You mix a small amount with your oil colour to thin your paint or thicken it and it also speeds the drying time. It halves the drying time of conventional oil colour (touch dry in 1-6 days depending on colour & film thickness).

It dries transparent but some people have found it yellows over time so you may want to avoid using it with whites or keep the proportion of Liquin that you mix with your paint small, although Winsor says it does resist yellowing.

Mixing alkyd in with your oil paint helps it be more crack-resistant, flexible and tough.