Preparing the panel
The panel, in my case waterproof plywood, has, just like all wood, a grain that have to be closed.
I use at least 3 layers of bone glue on all sides of the panel.
After allowed to dry thoroughly, 3 or 4 layers of (self made) putty is applied. Every layer have to be sanded down a bit.
After completely dried and sanded down to a smooth surface, two very thin layers of Gesso are applied, only needed to be able to apply the first layer of watercolour.
Like mentioned before, the first sketch is in watercolour (see picture1) drawn on the panel. The advantage of using watercolour is that it can be easily removed with a damp sponge, if its necessary to make some changes.
Now the watercolour image should be varnished, for two reasons, to preserve the image and because the panel would be to absorbent for the first layer of oil paint.
The first layer of oil paint exists of 3 basic colours. As you can see in picture 2, burnt umber, ultramarine blue and white is used. Other colour combinations are possible to.
On the parts of the subject, in this case the falcon, where light strikes the bird, a much thicker layer of paint is used. In the shadow parts the layers are thin (often the watercolour sketch can just be seen in the shadow parts of the finished painting).
When the underpainting is complete, thin layers of colour are applied, this is the stage of pure enjoy, the stage where the painting starts to "live".
Light parts are "highed-up" with white paint and reglazed again, its a technique where you have to be convinced on what you want to achieve. Big changes in this stage are almost impossible, you must have a clear vision in your mind of your finished painting.
It seems to be a cumbersome way of working, but its not. The drying times of the paint are minimal, because earth colours are used in the underpainting and also because in the glazing stage the layers are thin. I hardly lose any time waiting for paint to dry.
Its a technique not "invented" by me. In the 17th century this technique was common, its just a way of working that fits me but absolutely not the "Holy Grail".