So I can increase the size of the blob brush and eraser tool with [ and ], but the same shortcut doesn’t seem to work consistently with the brush tool. It works with the three small “standard” brushes, as well as the calligraphic brushes. It doesn’t show an increased stroke size, but the brush itself is affected.
It doesn’t work at all with Watercolor brushes.
Is there a reason for this or is this simply a bug?
Is there another way to quickly adjust brush sizes for all brushes other than changing the value in the command bar manually each time? In Photoshop it can be done by Alt-Right Click-Drag, but in Illustrator this seems to be something else entirely (creating a closed shape I think).
The way the brush tool works is that you’re specifically choosing the widths when you create them. So the watercolor ones will be created at a certain height or width, and then you manually increase or decrease them, add strokes etc. Blob and Eraser tools are done dynamically.
If you double click the brush, blob, eraser tools you get some options to play with, they may help you get a desired effect too.
Source : Link , Question Author : Alexander Rechsteiner , Answer Author : Rsiel