Soft erasers are most commonly used to remove pencil-written notes from books.
Eraser crumbs can be bought either in loose form or in small bags (as shown). In either case, they are sprinkled onto the paper and worked with the fingertips (The bag is only a dispenser and makes no contact with the paper.) They are used for the removal of dry smudge-type stains such as those made by soot or, not surprisingly, pencil lead smudges. Though similar in functionality to the dry cleaning sponge, the latter is better suited for the removal of dry, loose matter such as that which remains after cleaning with a brush or vacuum. Also, eraser crumbs are the better choice for use on delicate paper.