I normally tend to use pointed round brushes for watercolors, but every now and then I pick up a flat brush and use it throughout a painting. The other day I noticed some inexpensive flats on sale in a variety of sizes, so I picked up a couple to add to my collection. Now I have .25, .5, .75, and 1.0 inch flats, some firm, some soft. And tested them out.
Epson Scan used here – too lazy to putz around. The blue in the sky is granulated and light in color, but the blue in the water is too blue. The rest of the colors seem to be okay.
A flat brush is rather versatile. The longer edge makes for wider strokes, obviously. You can also load your brush with one color on one side and another color on the other side, and when you paint on wet paper, the results can be interesting. I didn’t do that here, but am writing this to remind myself I need to do it a bit more! The narrow side of the brush can give very nice straight lines, as you can see in the hay canopy in the mid-ground. Sharp edges, like in rocks can be easily expressed. Squiggly lines can also be achieved as seen in the too-blue-to-be-true water.
Watercolors, flat brushes, limited palette.
Ink, Yarn & Beer 
Good result!
Thanks, Fraggy! Always pleased when things work out – flat brushes seem limiting but really are more versatile than rounds at times.
Bob Ross was one for those I seem to remember.
He may have been, Fraggy . . . there is a watercolorist who used hake brushes almost exclusively but his name eludes me at the moment.