Friday, March 18, 2016

How to Oil Paint, Choosing colors for oil painting -- Part 4 of 4,

Van Eyck's The Marriage of Giovanni Arnolfini (1434)

How to Oil Paint, Choosing Colors for Oil Painting, Properties of Oil Paints...Drying Rate

Oil Paints unlike most other paints, change little as they dry in colour, but they do change slightly, becoming slightly darker and a little less brilliant. This is not really a noticeable change however.
So it is not really a concern to us as oil painters so much.

The rate at which the individual paints dry is important when you are building up a painting in layers. It is important to not paint fast drying paint layers over slow drying painting layers, until the slower drying layer is completely dry, in order to prevent the risk of problems occurring on the surface such as wrinkling or cracking of the paint in the future.

The very slow drying colours are titanium or zinc whites, ivory black, cadmium colours, vermillion and rose madder. Less slow drying but slow are ultramarine blue, cerulean blue and yellow ochre.

Colours with an average rate of drying are raw sienna, naples yellow, cobalt blue, chromium oxide (green), viridian, and earth red colours.

Fast drying colours are Prussian blue, raw umber, burnt umber, phthalocyanine blue, phthalocyanine green, flake white, burnt sienna and davy's gray.

So it can be seen that if you have a slow drying colour and you want to speed up it's drying rate, and you are also wanting to use a lighter shade, you can mix flake white instead of titanium white into the colour to quicken the drying rate. Alkyd mediums such as Liquin also help to speed up the drying process, although their primary purpose has been usually to make it easier for paint colours to flow under the brush.
If you like to see earlier parts of this article see Part 1, Part 2 and Part 3 for further properties of paint and choosing a palette for starting oil painting.

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