You may have noticed that oils come in averiety of ‘series’. The number of the series reflects the quality and intensity of the pigment, and the amount of them used in each colour. A good quality oil paint will have a nice buttery thickness as it comes out of the tube, and only a small amount will reveal a strong intense colour when mixed with white.
As you have been painting, you may have noticed that some paints dry faster than others, and some appear leaner or more transparent. This has to do with the original pigments that are used to create a colour.
Oil colours were originally made up from natural materials taken from the ground or plants, which in many cases have now been replaced by artificially manufactured alternatives. That made some colours very expensive, and in some cases very toxic, as things like arsenic and lead were used. These have since been banned in many countries for OH&S reasons. Artists who mixed their own oil paints prior to the creation of tubes durng the Impressionist period of the early 19th century, have used a variety of binders for mixing with the pigments, some modern artists still prefer to work this way, and access the raw materials for creating their own bespoke oils. Common binders over the years have been linseed oil, safflower oil, and lavender oil.
Each pigment in its raw state is made up of larger or smaller particles. These particles can be either smooth or rough. These differences will determine the amount of area that the binder needs to cover each particle, IE: how fat or lean the colour is. The amount required will change the way the paint reacts when applied to a surface, such as drying time, and how transparent the paint is. Many colours, especially in the less expensive brands, are now made up of manufactured pigments however it appears that the principle of how these man-made pigments react with binders is still relevant.
For example, cadmium red has a large area to cover as it has large smooth particles, but alizarin crimson has more area to cover because of the amount of small irriegular particles. Test these for yourself to see which is the fattest or more opaque by thinning the paints out with more medium like artist’s linseed oil. You may also ask at your art supplier if they have paints that have natural pigments and manufactured ones, so that you can sample each to determine which you can afford, and prefer to use by testing them.
For more info, and a video go to the link below. Thanks to Winsor & Newton for another informative mini masterclass.
Reference:
http://www.winsornewton.com/au/masterclass-video-oil-absorption-rates?dm_i=4QA7,GS1,FFRLV,1AGR,1.
Janice Mills 