Filament manufacturers like Dupont have since learned how to impart the qualities of a good China bristle brush to their products, but for the sake of cutting costs, some companies today make synthetic filaments that are as primitive as their predecessors. Of particular interest right now is the Chinex filament, which is designed to be used in both latex and oil, and manufacturers are jumping on the bandwagon. But with level filaments, the brush tends to dump the paint, said Babkowski. Tapered filaments of varying lengths form a kind of ramp that paint runs down. Level filaments form a stairway and a rougher route for flowing paint.
Solid filaments are more durable.
And if they're bent, they'll return to their original shape. If hollow filaments are bent over, they stay bent. Hollow filaments also tend to suck up the paint inside, making the brush considerably more difficult to clean well. Reighard also recommended brushes with round filaments. Feathery flags, for example, don't pick up viscous coatings very well.