In this stage, I'm going to add detailed flat colors based on the color scheme draft.
 Preparing to paint flat colors
■ Hide the paper layer
I make it so that only the lines are visible on the canvas so that it is easy to find unpainted areas.
I hide the paper layer at the very bottom.
Any transparent areas that haven’t been drawn on show as gray tiles.
Note: For reference, I filled the cat in white and kept the layer visible.
■ Brush settings
Next, I set up my brush for flat colors.
If I paint with a brush that reflects pen pressure, gaps and thinly painted areas are more likely to appear. Because of this, I change the default settings to not reflect pen pressure.
I choose the [Pen] tool > [Pen] > [G-pen] and uncheck [Pen pressure] in the [Effect source settings] dialog box.
You can check that pen pressure is turned off by looking at the stroke preview shown in the red frame below. When turned off, the brush thickness will be consistent.
 The girl's skin
After setting up my brush, I start coloring the skin.
In the [Layer] palette, I hide all folders and layers except for the “girl” layer folder.
■ Coloring the skin
I create a new “color” layer in the “girl” folder and color the skin using the [G-pen] I just set up.
I can change the color later, so at this stage I use a dark red so that I can easily see any areas I’ve missed.
If you find any uncolored areas when there are a lot of layers, it can be a pain to fill the gap, so I try to prevent leaving any uncolored areas at the flat colors stage.
You should paint flat colors from the bottom up. This time I started by coloring the skin.
Color for the hair and the clothes will be layered on top, so I color roughly over the lines.
By doing this, I make it less likely that there will be small gaps when I color the parts on upper layers.
■ Changing the skin color
After coloring the skin, I reference the color scheme draft and change the color.
I go to the [Edit] menu > [Tonal Correction] > [Hue/Saturation/Luminosity] and change the color using the sliders.
To change from dark red to a skin color, I increase the value of [Brightness] greatly.
To add more yellow tones, I move the [Hue] slider to the right
I adjust the values while looking at the results on the screen.
Once I have the color I want, I rename the layer to “skin” and turn on [Lock Transparent Pixel].
 Coloring the eyes
I create a new layer above the “skin” layer and color the eye in red.
Although it looks a bit scary, it’s hard to see white clearly on the skin color, so I use a dark color again.
Once I’ve finished, I change the color like the skin.
Rather than a brilliant white for the eyes, I use a subdued color with some yellow tones so that it blends into the skin tone.
Then, I erase the area around the inner corner of the eyes a little.
Since the shape of the whites of the eyes affects the impression of the face and the line of sight greatly, I make quite detailed changes.
After I’ve finished adjusting the shape, I rename the layer “whites” and turn on [Lock Transparent Pixel].
Next, I create a new layer for coloring the iris in green.
Hint: Lock transparent pixels
To reduce mistakes when working on my project, I turn on [Lock Transparent Pixel] for all flat color layers.
For example, this prevents me from mistakenly coloring on the hair layer when I color the skin.
It also prevents drawing outside of the color area when painting the shadows later.
 Coloring the hair
Since many parts of the hair overlap with the lines for the face, I temporarily hide the lines of the face to avoid missing any areas.
Now I can color the hair.
I color smaller parts such as the hair tips so the color goes out of the lines. Then I erase any extra color with the [Eraser] tool.
I paint the tail on the same layer, as it is the same color as the hair. As with the skin, I start by painting a dark color and then change to white.
I chose a color with a slight yellow tone so that it looks more realistic as the hair of a living creature.
 Coloring the ear
Next I color the inside of the ear.
I make a new layer above the “hair” layer, and turn on [Clip at Layer Below].
I color while leaving a little bit at the edge uncolored.
I select the [Brush] tool > [Watercolor] > [Transparent watercolor] brush, and paint with [Pen pressure] turned off. I use a large brush size of about 100 pixels.
When I paint the ear with this [Transparent watercolor] brush, it creates a gradient.
After blending the colors, I open the [Edit] menu > [Tonal Correction] > [Hue/Saturation/Luminosity] dialog box and change the color, like with the hair.
I changed it to a healthy pale pink color like a real cat.
I rename the layer to “ear” and turn on [Lock Transparent Pixel].
I’ve finished coloring the body parts now. Next time, I’ll color the girl’s costume.