Brush Flow and Opacity Settings
Now we should talk a little bit more about our brush because there's something I neglected to talk about and that is a lot of people want to know the difference between opacity and flow. And so I'd like to show you the difference there. When I choose a brush and I start painting with it, it looks at both the opacity and the flow settings to determine how much you can see through my brush. And if they're both at 100% when I click and drag like this in the very center of my brush you will not be able to see through the middle at all. I'll choose undo. If I change the opacity setting then you're going to be able to see through my brush and so if I bring that down, let's say I brought it down to 20% or somewhere near there. Now when I click and I drag, you can see that I'm only getting a hint of this color showing up and then I can go back and forth and back and forth and notice if I go back and forth I'm not getting multiple coats of paint. It's not like having a can of spray paint where ...
the more times you go across, the more coats you get. But if I do let go of the mouse button and I click again which I just did, we get a second coat of paint. And it doesn't matter how many times we paint across it, it's only two coats now. Let go again and click, and I get a third coat of paint. Then I can let go, click, and get a fourth. But to build up the effect I have to let go of the mouse button and click again. I'm going to choose undo a few times to get back to what we had earlier. Now let's bring opacity all the way up to and instead bring flow down to around 20%. And let's try the same thing. I'm going to click here and I'm going to drag and then I'm not going to let go of the mouse and I'm going to drag and drag and drag across the same area multiple times. So flow means how much do I want in my first paint stroke across the area, but if I paint across it again I'm going to get more and more and more. So you can think of adjusting flow, it's like using a can of spray point where the more times you go across an area the more coats you get. The difference being that if you go slower you don't get more. And faster getting less 'cause you get that with a can of spray paint. But it's just counting the number of times you go across. Then you can use flow and opacity together. If you bring opacity down, lets say I have it at 50. In fact if you use the number keys on your keyboard you're going to be changing the opacity if you're in the paint brush. So if I take five I get 50%, take nine you get 90%. We'll type two numbers very quickly to get a precise value. Like 32%, you gotta type three, two really fast. So if I set opacity to 50% and I set flow to, lets say 20%, how does that work? Well in the end it's going to be that opacity determines the maximum amount you can get without releasing your mouse button. So that means I'll never get more than 50% opacity. Flow means how much of that maximum am I going to get on the first pass. So I'm going to get 20% of 50. Then if I paint back and forth and back and forth and back and forth, it's going to build up but it's never going to get above whatever the opacity is set to unless I release the mouse button. And only then could it add more. So flow and opacity can be nice. It's a matter of do you want it to build up as you paint across and across. If so, adjust flow. Or do you want it to not build up? If you happen to overlap your paint strokes and you have to release the mouse button in order to add more, if that's what you're looking for, instead be using opacity. And some people will get fancy and use both. The number keys on your keyboard will change opacity when you're in the paint brush tool. And if you hold down the shift key when you use the numbers, it will change the flow. Typing zero brings it to 100.