Painting a portrait in aquarelle watercolours is pretty hard. There is so much risk with things going wrong, that's why it is important to have a good attitude towards it:first of all, realise that you may have to tear up your work and start over, and secondly, try out the important parts on the same type of paper that you are going to create the painting on. One of the (many) important parts of a portrait is 'Hair'. There's blond hair and dark hair and everything in between, there is short and long hair, straight and curly... It takes some study to get 'em all under control... And the one I had never really practiced before was 'short frizzy hair', most seen on black children - and on Pim :°).
Try-out 1. Wet-in-wet, start with the colours of face and skull. Then on top of that, while still wet, very dark dots (I used a mix of sepia + payne's grey) then let dry, then background.
Make sure you prepare! You need to know what you are going to do, make enough paint, decide on colours. Don't draw at all or just some thin help lines...
Try-out 2. on wet surface, the skin and skull colours, leaving out highlights. Then very dark paint approx where the hair is, then add salt. For me this doesn't really do it, but I'm sure others like Cathie could make it work!
Also working well for me is to experiment on one page, divided in 4 or 6 parts using masking tape. That way you have only a small surface to fill each time - and you don't ruin too much of your expensive watercolour paper!
Try-out 3. just the hair, to see if I could get it darker as the salt takes out the 'dark' as well. So this one sure stayed dark but I considered it a fail as it doesn't look one bit like curly hair...Yet in the right context I might get away with it!
Try-out 4: Another fail, the difference with nr3 is that I wetted the paper first. This might actually work for suggesting fur, or sheepskin, so it was useful as experiment...
Try-out 5: Wet the paper with clear water, then dot the hair in darker and lighter (more and less pigment) shades. Let dry, then add the skin colour and shadows. Then the background - which can also make the impression of short curls stronger. This method worked the best for me...
Try-out 6: Same as number 5, but now with a part of the face of an African boy. That helps!
Conclusion: The suggestion of curly hair is more important than the details. It looks right if the rest of the painting is clear - the brain will automatically 'connect the dots' because of the context... A background that leaves out the curly shapes helps explain your picture.
The technique you use is personal, I prefer the wet-in-wet, but I'm sure that good results can be achieved with salt, or by painting all curls seperately with a one-hair-brush. And always keep an eye on the light, make sure your shadows are consistent and don't be afraid of a bit of contrast!
Soon we will spend more time on portraits in aquarelle!!