How Oil paint is made and its properties


How do they make Oil paint? This is a simplified explanation of how oil paint is made - the paint pigment is ground together with a binder, usually linseed oil, although other oils are used depending on the pigment type. Bees wax can be added, also driers and stabilizers. By hand the process involves - first mixing the paint pigment with the linseed oil to a crumbly mass on a glass or marble slab. Then a small amount at a time, is ground between the slab and a glass Muller (this is a round, flat bottomed glass instrument with a hand grip, like the one shown right). Pigment and oil are ground together 'with patience' until a smooth, ultra fine paste is achieved, this is then placed into jars or metal paint tubes and labelled. In commercial paint manufacture, years ago pigment and binder were ground together between special stones, now the paint pigment and binder, sometimes called a vehicle, are milled together on large steel rollers. The resultant paint then goes through many tests before being put into familiar paint tubes, a label is applied with full details of the contents and it then arrives on the shelves in an art shop. The more important properties of oil paint. The information on the label will tell you a lot about the paint:- the name of the pigment or pigments used, followed by the pigment number i.e. Burnt Umber is PBr 7 - PBr stands for Pigment Brown, PY Pigment Yellow and so on. The label also tells you about the vehicle or binder the paint has been made with, the vehicle is often Linseed Oil, although Safflower Oil is regularly used for light colours. The light fastness - this is shown by a star or number rating (usually the higher the amount the more lightfast), e.g. a high lightfast rating would indicate this colour is less likely to fade than a lower rating when used under normal conditions. Another symbol or wording is used, to state whether the paint is opaque, semi-opaque or transparent. A caution notice if it is required. Back to Colour Mixing Oil Paint can be transparent, translucent or opaque. If you are not sure which, an easy way to check is put a dark line on a piece of white card, use a brush to put a thin layer of paint across the line. If you can see the line it's transparent, if the line isn't visible it's opaque, if the line is indistinct but visible it's translucent (often referred to as semi-opaque). Another property of oil paint is its drying rate. The earth colours (as they are often referred to) tend to dry the fastest. These are usually made from iron oxide:- Burnt Umber, Burnt Sienna, Raw Umber, Raw Sienna, Light Red, Mars Red, Mars Violet and Mars Orange. These are often applied at the beginning of a painting, their fast drying makes then good for underpainting. The slow dryers tend to be Titanium and Zinc White, Alizarin Crimson, some Yellows, Green Earth and Ivory Black. These are often applied towards the end of a painting, this helps maintain the 'fat over lean' principal more information on this can be found on the techniques page. Back to Colour Mixing Paint has three other properties concerned with it's colour:- 1) Hue; 2) Value; 3) Chroma, this is covered on the Colour page. Oil Paint can also be thinned, usually with a solvent like Zest-it or painting medium, this gives different qualities to the handling of the paint and the way it behaves after being applied to the canvas. It can also be used 'as is' straight from the tube, especially where texture is needed. Some people also add wax paste to the paint, this again will give a different look and feel to the paint. Copyright© Jacqui Blackman 1999