17 October 2008

On underpainting

The colour in the previous post’s pics is the watercolour and gouache underpainting. Once I’ve done something similar to the Piero one, I’ll start on the oil glazes for all three.

The idea is to build up layers of transparent colour (except for the gouache). In the finished painting, the light passes through these transparent layers and reflects off the white ground, giving it an inner glow.

Traditionally, you’d use oil paint diluted with turps for the underpainting. The reason for using turps is Rubens’ principle of ‘fat over lean’, where you put layers with more oil content over layers with less (to prevent cracking). The problem is that different pigments have different amounts of oil added to them to make oil paint, which complicates this process considerably.

My solution is to avoid the problem and use watercolours instead. Needless to say, they have no oil content. I then only have to worry about the glazes. That’s bad enough. I’m quite capable of getting horribly confused.

The other aspect of underpainting where I depart from tradition is the choice of colour. Traditionally, you’d use monochrome, usually in grey (called grisaille), or complementary colours. So in the latter case you’d underpaint the sky orange and the grass red, etc. As you can see, I do neither.


John said...

Ad Reinhardt had an interesting technique of mixing the oil paint with turps and then letting it sit for a month.The oil would rise to the surface,be decanted off,give the jar another shake,then repeat the process.The result ,after a few months is that you have something approximating purer pigment through concentration.....but also an avoidance of 'expressive' aspects eg brushwork.
Actually really beautiful 5ft square works which require physical looking and a waiting period as no light is being reflected back,nor is light being diffused through the painting surface.
The drawback of course is that without oil the surface is very brittle and almost hopelessly susceptible to marks.

David Cauchi said...

Nothing wrong with a few marks.

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