The waterbrush tip size determines how much water is dispensed with each brush stroke. Fine brushes release less water per stroke and are good for detail work while large brushes are suited for covering larger areas.
So you got yourself a water brush, now what? Well, there are a few things you can do with it, of course, you can use it to paint beautiful landscapes, people, abstract art and more, but here, we'll use it for lettering. But before you get to that part, (coming next week) let's talk about the different way to use it and how to take care of it so it lasts you a long time.