In Vanitas still life of '600 it is easy to find in the painting pocket watches often with a blue ribbon to safe the key instead of a chain; does anybody know the reason of this choice? why it is always blue? is there a book that explain and recognize the models of watches and clocks portraited in the still life of '600?
thank you in advance for sharing your knowledge on the argument.
I supposed they are watch and not compasses for the key to wind