The materials and procedures of the 19th-century lithographer are duplicated in almost every respect by the contemporary hand printer. An image is drawn with tusche (a carbon pigment in liquid form) and litho crayon before the printing surface is fixed, moistened, and inked in preparation for printing. The printing itself is done on a press that exerts a sliding or scraping pressure.
The dream about keys is a dream that refers to solutions to one's life problems. The question you have to ask yourself when you have this type of dream is 'what is the problem I have today that needs a solution, or a key? (read all at source)
To dream that you are in a library signifies your search for knowledge and your hunger for ideas. You may be trying to seek out new meanings to life. You need to study and evaluate your situation before taking action.