Why do some artists not sign their paintings?
Considering this, why would an artist not sign a painting?
The artist's signature has become a key ingredient in the art-making process—it signifies that the artwork is finished, and that the artist is satisfied. The right signature can even turn non-art into art. So when artists first start painting, most often they sign their work simply because that's what artists do.
Secondly, do all artists sign their paintings?
Your signature identifies your art for all time as having been created, completed and approved of by you and you alone (with the exception of collaborative works, of course). No signature. Believe it or not, a significant percentage of artists these days don't even bother to sign their art.
For example, many drawings in the market which cannot be attributed to Rembrandt yet have all the physical attributes of a Rembrandt are sold as “school of Rembrandt.” While an unsigned painting by a particular artist would have less value than a signed example by that very same artist, unsigned genre paintings do not