What are the three oil painting rules?

When you’re using oil paint, a composition is usually built up using different layers of colour. For example, if you’re painting a portrait, you may start with an area of background colour. On top of this you may sketch out the proportions of the portrait with another colour, and on top of that you may add further colours for the detail. The way each of these layers of colour interacts with each other is important and will affect how your finished work looks.

If you want to make the most of your painting, there are three tried and tested rules that will serve you well:

1. Fat over lean

First up, is what’s known as ‘fat over lean’. Think of this rule as meaning ‘flexible over non-flexible’. To prevent your paint from cracking, each layer needs to be more flexible than the one underneath. Just add more medium to each new layer to make it more flexible than the previous one.

To make it even easier to achieve this you can use a range of Winsor & Newton mediums, so that there is no need to keep on adding oil to your colour. One of the most commonly used is Liquin Original.

2. Thick over thin

Next, is ‘thick over thin’. When painting with heavy colour, it is best to apply thick layers over thin layers. This is because the thin layers dry more quickly. For example, if you like the impasto style of the Impressionists, with their thick, bold brush strokes then it is important to remember that these thick layers need to be uppermost: thin layers on top of impasto layers are likely to crack.

3. Slow-drying over fast-drying

Lastly, we have the ‘slow-drying over fast-drying’ technique. If fast-drying paint is applied over a slow-drying layer that is still in the process of drying out, the latter will pull and twist the layer above, making it crack. So it’s best to always use fast-drying colours as underlayers.