Editing Photoshop Brushes How-To (section)

== Brush properties ==

* '''Flow''' is the amount of color that is laid down by a brush with each stroke. <ref>[http://blogs.adobe.com/jkost/2017/05/brushes-and-painting-tool-shortcuts-in-photoshop-cc.html 20 brush and painting tool shortcuts in Photoshop CC] - Adobe Blog</ref>
* The '''airbrush''' option allows the brush to build up opacity as it covers over an area. With '''airbrush''' selected, '''flow''' controls how much color is laid down, i.e. you probably want a flow less than 100% when using the airbrush option. 
* Also, when a brush does not have the '''airbrush''' option, pressing the number keys, 1, 2, 3...0, changes the '''opacity''' of the brush, while pressing Shift and a number key changes the '''flow''' value. When a brush has the '''airbrush''' option on, the number keys changes the '''flow''' value, and Shift + number keys changes  the '''opacity'''.