Lately I have been framing about half my works without a mat, in Plein Air Style frames, with museum glass or plexi for glazing.
I think this works because my paintings are fairly saturated in value and don't have a lot of white paper.
I do this frequently when I am exhibiting with mostly oil painters in exhibits or galleries. I don't know if this will be acceptable to watercolor societies as well, I will let you know what I find out!
The photographs are not as good as they could be, I originally took them for my own records and not for publication.
Here are a few of my recently framed paintings:
The photo dosen't show it but the frame is dark red that shows off the painting well.
Fairmont Gallery, Sonoma
Fresh Greens 18 x 24 , on it's way to the American Impressionist Society Exhibit