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Understanding the three oil painting rules
Opus Resource Library

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:

Fat over lean

Each successive layer needs to be more flexible than the one underneath. This can be done by adding more medium to each new layer, which makes it more flexible than the previous one and stops the painting from cracking. Think of the rule as “flexible over non-flexible”.

Winsor & Newton offers a range of mediums to help create this flexibility within layers. One of the most commonly used mediums is Liquin Original. Using it means there is no need to keep on adding oil to your colour.

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.

Slow drying over fast drying

It is best to use fast drying colours continuously as under layers. If a fast drying layer is applied on top of a slow drying layer then your painting may crack. This is because the fast drying layers will have dried on top of layers that are still in the process of drying out, and as the slow drying layers dry they will pull and twist the layers above, making them crack.

Article Source: Winsor & Newton