Techniques

Pencil

I use very soft pencils for the broader areas and a mechanical pencil for the details. A kneadable eraser is a wonderful tool to correct shading and to add highlights. Sometimes I wipe some graphite filings over the paper to make dark backgrounds

Plain pencil sketches are the fastest way to make a convincing illustration.

Coloured Pencil

The weak colour of coloured pencils allow very accurate shading. However, it's painfully slow.

Pastel

A quick way to get strong colours. But control isn't too good, and it's a dusty affair.

Egg Tempera

The colours are just wonderful. I don't use the recommended cross hatching technique (I tried it without success) but try to make shadings by adding thin transparent layers. I often add chalk to make colours more transparent.

Oil

As I already have raw pigments for egg tempera, I use them for oil paintings as well. I don't use any solvents. Instead of reducing the amount of turpentine, I increase the amount of slower drying oils from layer to layer. I store my brushes in a brush pot filled with non-drying oil. As I paint very thin layers, the drying time is not too bad.

Gouache

Gouache is currently my paint of choice when travelling. By adding egg, it can even be used for egg tempera without having to carry dusty pigments around. The flatness of gouache is not ideal for rendering nudes, though.

Casein

From what I've read, they're somewhere between egg tempera and gouache. I'm currently experimenting with curd cheese and alcalic mortar, as I couldn't find ammonia or borax in the local shops. The first tests look promising.

This was done with low fat curd cheese and salts of hartshorn (ammonium carbonate). The mixture smelled horrible, but worked well. Layering works to some extent.