Hi ednah and Tony,
It's good to see some newcomers to The PainterFactory discussing Painter. Welcome!
While Painter's Digital Watercolor ("DWC") and Watercolor ("WC") brush technology is quite advanced, there are still things we'd like to see added, such as what you've mentioned.
There's a lot we can do, but it takes some experimentation and practice to learn how to control both DWC and WC brush categories.
Maybe these two John Derry Visual Guides for Digital Watercolor and Watercolor will help:
Painter 8 Tutorials
Since they were written for Painter 8, you'll notice spelling of the brush category names is different from what's used now (Digital Water Color vs. today's Digital Watercolor and Water Color vs. today's Watercolor).
A more important difference is a great improvement in Digital Watercolor since Painter 8 introduced that brush category. In Painter 8, wet DWC paint was automatically dried when the file was saved, closed, and opened again, whether or not the artist wanted it dried and even when the file was saved in Painter's native RIFF format.
That problem was fixed in Painter IX and now we can save a Digital Watercolor painting in RIFF format, close it, then open it again in Painter and continue, with the Digital Watercolor paint still wet until we decide to dry it.
When reading John Derry's Visual Guide for Digital Watercolor, you'll see that he mentions the drying of wet Digital Watercolor paint when the file is saved. Don't let that worry you. Since you're using a more current Painter version, it shouldn't be a problem as long as you save in RIFF format to retain all Painter-specific information. In this case, that would be the invisible Wet Layer, the ability to edit existing DWC brush strokes with DWC brush variants, and the expected look of wet DWC brush strokes.