There are many different oil painting mediums that can aid and enhance your portrait paintings. For instance, most mediums are designed to dilute or thin paints helping you create thin glazes for painting techniques such as sfumato, which require subtle blending and fine detail, others are used to enhance the body of the paint, perfect for impasto.
In this article I will be highlighting some of the best oil mediums to use for blending and glazing in portrait painting:
Winsor & Newton Liquin: This low gloss liquid alkyd medium is used to improve the flow of oil paint and smooth out any brushwork, it also increases transparency making it the perfect medium for thin glazes and blending work. Also, by smoothing brushwork it is ideal for finer details. Liquin can also accelerate drying by up to half the usual time depending on the oil colour to medium ratio.
Refined Linseed Oil: Although usually mixed with turpentine to create an oil painting medium, refined linseed oil can also be used on its own. Linseed oil increases the fluidity of paint and also the transparency so again it is an ideal oil medium for thin glazes and blending. Retards drying allowing you to work longer with the paint.
Roberson-Parris Marble Medium: Roberson-Parris Marble Medium is made from refined beeswax, turpentine and a synthetic copal varnish or dammar resin. Mixed with oil paint at a ratio of 1:3 and diluted with rectified spirit of turpentine, this oil medium is used to create a non-reflecting matte like surface that can be ideal for creating the illusion of depth, especially for dark backgrounds behind a portrait.
Spectrum-Alkaflow: Spectrum-Alkaflow is an alkyd based oil painting medium that is used to thin oils and smooth out brush strokes. Its effects are similar to Liquin, although Alkaflow is a bit more viscous and creates a gloss-like finish. So again it is an oil painting medium perfect for thin glazes however the shine it creates is more ideal for areas such as the eyes or lips to give the interpretation of moisture or shine.
Roberson-Glaze Medium This oil painting medium is exactly what it says on the bottle; an oil medium you mix with the paint specifically to create thin glazes. It improves the flow of the paint and so is therefore ideal for blending and finer detailed work as well.