If you look after your paint brushes well—which includes cleaning and maintaining properly, however long-lasting it can be—they will last. You can consult several signs listed below to consider replacing your paint brushes:
Start missing the point: The brush eventually won’t produce the thin, even lines it once did.
Feel the worn-out: Stiff-hair brushes, sometimes wiggle, wear down the quickest, primarily when used on rough surfaces such as unsanded gesso.
Bristles going bald and wear-and-tear.