Recently, a reader asked what brushes I use. If you look through the art supply catalogs, you'll see an overwhelming variety of brushes used for oil painting. You can get rounds, flats, filberts, riggers, fan brushes and even brushes tailored to create little marks that look like leaves. You can get them made of synthetic fiber or natural fiber such as sable, hog, squirrel and possibly even catamount. You can get them with long handles, short handles and also very short handles that will fit into your pochade box. There are almost as many choices for brushes as there are for paint colors.
Well, I like to keep things simple. I use natural hog bristle flats, period. The flat is incredibly versatile. With it, I can make wide strokes, thin strokes and dots. I can scrub on paint vigorously, or I can let off the gas a bit and make delicate, twig-like strokes. As the flat wears down to more of a filbert shape, I can make very soft, blended passages. Also, the natural hair seems to have a more gentle "spring" and fits my style of painting better than the "snappier" synthetics.
For painting outdoors in a 12x16 format or smaller, I use sizes 2 through 10. I don't go for the short brushes or the long brushes - the short ones are too short for my style, and the long ones are harder to control when painting in a small format. To keep my load light, sometimes I'll only take out a couple of brushes. For a 9x12, I may use only two flats - a size 6 and a size 8.
Although there are many fine brands out there, I've settled on Silver Brush's "Grand Prix" line.
Yes, I do have a rigger or signature brush and a few sables. If the painting has dried so much that I can't scrape my signature in with the end of the brush handle, I'll use a rigger to paint my signature. If I'm in the studio using glazes, I'll use the sables, which won't damage possibly soft paint layers. I don't carry either of these into the field, though.
By the way, in my online Udemy course, I have a video lesson on how I handle my brush. I should also mention that you get the full Udemy course as part of my upcoming Artist's Network University online course, which starts January 8. This is a four-week course in which you get weekly assignments plus personal critiques from me. Click here for the Artists Network University course.