Originally Posted by 0lBaldy
When you paint a color you want to use the color you picked, If you use low Opacity then the colors you picked will be sort of watered down or muted, so you use full opacity (which can always be changed later in the layers pallet) and just use a little at a time (flow) to build it up..
Try a test using both settings side by side to compare the difference
I tried and i see the difference, but i don't understand the advantage. Maybe you know a website that can me give more information about this?