When most people digital paint they tend to default to using opacity to layer and blend their colors. However many people don’t fully understand the other option. Flow. Both Flow and Opacity allow us to control the transparency of our brushes.
What is Opacity
Opacity is the opaqueness or transparency of the brush. When using opacity the amount of color being added to the canvas is the same you are only changing how see-through it is.
What is Flow
Flow is how much color is being added to the canvas. Flow gradually adds color from no color to full color.
Opacity VS Flower in application
If you draw a dot with 25% opacity and 100% flow. Then draw a dot with 100% opacity and 25% flow. These two dots would look identical. However if you were to shade an area back and forth with each of these settings the one with 25% flow and 100% opacity would have s more saturated color. This is because flow adds color continually. Opacity only adds every time you pick up and put down your brush.