
What is a Filbert Brush? The filbert brush is a type of flat and narrow brush that features hairs that end in a rounded point. When used on its side, the filbert brush delivers a very thin line. When used flat, the filbert brush can create a broad brush stroke. This is also an excellent brush for making tapering marks. Filbert brushes constructed with bristle or hog hair tend to wear down with use, but this is often when they are the most useful. Filberts that have been worn beyond use can be very handy for dry brushing.