When is a painting finished?

I know that many artists face this dilemma when they are making work – not quite knowing when a painting is finished. Sometimes I think a painting is finished, I paint the edges, putting hanging wires on, even exhibit it, and then get it back to my studio and find myself playing with it again, because I can then see it more clearly and can see what I need to do to get it to the right place. Here are some recent examples, with Before and After images:

Before: Saltmarsh Recollections 1

Saltmarsh Recollections 1 SOLD 61 x 61 cm £420

Before: Saltmarsh Silence

Saltmarsh Silence, 61 x 61 cm, £429

Before: Breathing Spaces 3

After: Breathing Spaces 3, 30x30cm £180