B/W tonal underpainting

[dashinvaine]

This question primarily relates to traditional art, especially oil painting...

When doing a black and white tonal underpainting, is it good to take it to a fairly high level of detail? My instinct says yes, but then it's almost like painting two finished paintings, one on top of the other. I suppose with more detail underneath you can get away with just doing washes when it comes to the colours, but still it can look a bit dull that way, with the grey showing through. Also, as an idea, is it advisable to paint a tonal wash over the whole area of the b/w underpainting prior to commencing the final colouring, so that there are no areas of grey showing?

[bjoern3000]

What you mean is called a grissaile and it is done without detail. Detail comes with the upper layers and glazes.

If you do something wrong in the grissaile you can never correct it in the upper layers unless you paint without glazes.

And: the grissaile is made without extreme lights and darks. These come with the following layers. If you do a part too dark you can not make it lighter with glazes. And since glazes are applied in the dark areas of a painting and every glaze darkens a bit more, you must not make the underlayer too dark.

Your second question: it depends

[Ninjerk]

In my painting classes we've used only burnt umber in the grisaille (although a couple of us have experimented with using white and orange to various degrees so we can go from the gray canvas upwards as well) and controlled tone primarily by thinning the paint in the areas of light. You can get a fairly detailed painting (for a student) by doing this.

[dbclemons]

...When doing a black and white tonal underpainting, is it good to take it to a fairly high level of detail? My instinct says yes, but then it's almost like painting two finished paintings, one on top of the other... Also, as an idea, is it advisable to paint a tonal wash over the whole area of the b/w underpainting prior to commencing the final colouring, so that there are no areas of grey showing?

In my experience, detail is unecessary at the start. Mainly due, as you mention, to being a waste of time since it gets painted over. I treat the undertones as broad shapes with the edges overlapped by new layers, sort of like coming into focus. I also keep those values in the mid range: from a scale of 0-10, use about 3-7.

There is a traditional verdaccio technique that involves a greenish or dead layer tone in the early stages as well. That mostly works for skin tones. I often start the painting in neutral complementary tones to the base color, rather than completely monochromatic, which is a similar idea.