I had to stop painting halfway through a new work yesterday - my pet peeve - largely
because I struggle to get back into the zone of things when it's all dry and at that middle bland stage of light and mid values.
so I'm writing a list of what I need to finish, what I'm happy with, what I'm not happy with etc etc.
This also leads me to look at my pencil marks. The problem with pencil marks in watercolour is the danger of "paint by numbers", of being confined by the marks which leads to tight painting restricting the artist's creativity (read my article about nasty drawing.
I leave the ones that are lyrical and poetic and gestural and say what I want to say, they can be so beautiful.
However, during this process I also erase pencil marks that annoy me or are wrong or make the shape unclear to me or my viewers.
if you are using good paper like Fabriano Artistico or Arches aquarelle, marks underneath a transparent pigment will disappear easily (make sure it's really dry, erase the day after you paint). From under other pigments you might have to get quite rough with your eraser and marks will be difficult to remove from opaque colours (especially yellows).
Use a good quality plastic eraser like Faber-Castel and a kneadable eraser, if one doesn't do the job, the other might!!