Building a face by layering values in a one-color portrait
Doing a one-color (monochromatic) portrait helps you understand the features without worrying about "what color do I use?" or "warm or cool?". Below is a finished monochrome of my #2 daughter. I used burnt sienna throughout, and when I needed to darken the hues I used bits of French ultramarine and less water when burnt sienna would go no darker.
For this demo, I am using French ultramarine throughout because it can go from a very pale blue (when watered down) to a very dark value.
First mask out any pure whites you want to save. I only masked the highlight in the eyes and a few things strands of hair and a small highlight on the tip of the nose.
When masking is dry, cover the entire face in a pale wash for the lightest values. If I feel confident enough, while the first value is damp, I create a slightly darker wash (by adding more paint to the puddle I've created), then paint over everything that is darker than the first wash. You should now have two values painted, but they should blend softly, no hard lines between the values. Dry the painting.
In this blue version, you see where I wet the entire face and hat, then put a very diluted solution of paint for the lightest layer. Since it was still wet, I put in my second value in any place that would eventually get darker: under the hat, on the neck, around the eyes near the upper nose, under the chin, etc I was using the water to keep the edges very soft at this point. BUT IF your first layer is not damp all over, dry it first. Then wet the area and put in your second value anyplace that is darker than the first value.
I am using my 3-or-4 value from Notanizer to give a general idea of where to place the next values. BUT this does not mean this will only have 3 or 4 values. I also look for nuances in the black and white photo to make decisions.
Here is my next layer of value.
Wet the painting again only in areas where you want to paint values darker than the first two. Large areas--under hat, around nose, chin, neck, etc--are wet in wet. Smaller areas--ear, iris, mouth, are on dry paper. Increase the darkness of your paint by adding more paint to your puddle, and again add darker paint to anything that is darker than the first two values. Dry the whole painting.
This next layer is completely on dry paper, as I'm dealing more with small spaces with some hard edges. I've painted in the mouth and eyes and some details and shadows on the hat. Dry again.
I've added another darker layer beneath the hat and some background. For this darker layer, I added some indigo to the French ultramarine mixture. Dry again.
I added some background.
Finally, I reached a point where I can do some lifting and corrections. I removed all miskit, then lifted just beneath the eyebrow; on the cheek; on the lips; a little around the mouth; some softening around the nose. I'm not completely happy with the chin, but if I mess too much with it it will make a mess. Mostly it has been a process of adding one value layer over another, then sharpening some details.
By the time you have 3 or 4 values, the spaces you paint will get smaller and smaller. You can switch to the wet on dry method, but you are always smoothing the edges to keep them soft. Examples of this would be around the nostrils, which gets pretty dark, but must be softened into the lip and cheek areas.
This is the most valuable skill for painting portraits: learning to keep the edges soft. When you need to soften edges that are still damp, apply the paint; then clean your brush, dab the water out of it, and use this to pull out the edges so they are softer.
TIP ON MIXING YOUR PAINT:
FIRST put the amount of WATER you want to use on the palette well. Since you will be using the same color over and over, make plenty so you don't have to keep mixing it up.
Second, add the paint a little at a time until you have a very diluted mix. Test it on a scrap of paper to see if it is dark enough.
REMEMBER that this is wet in wet, so your color will be even lighter because you will be adding the paint to the wet paper.
When you have your first layer, then add a little more paint to the water mix to kick it up a value or two.TEST it on scrap paper to see if it is dark enough (or too dark). Adjust the paint to water ratio until you get the next value. Make sure there is enough to paint the space you need to cover so you don't have to keep dipping into the paint and remixing.
Painting Noses in Watercolor
Here is a short YouTube on painting a nose in watercolor:
https://www.google.com/search?q=painting+nose+in+watercolor&rlz=1CATRIY_enUS1088&oq=painting+nose+in+watercolor&gs_lcrp=EgZjaHJvbWUyCQgAEEUYORigATIHCAEQIRigATIHCAIQIRigATIHCAMQIRigATIHCAQQIRifBTIHCAUQIRifBdIBCTczMTRqMGoxNagCCLACAQ&sourceid=chrome&ie=UTF-8#fpstate=ive&vhid=lZHstyBTeucikM&vld=cid:9ec2fc96,vid:kYmNGO8C9jg,st:0&vssid=l
You can also refer to my blog of May 2017 for nose
https://www.blogger.com/blog/post/edit/8812132386157895665/7104778837003534086.