Pyyhekumi

Pyyhekumi, also known as an eraser, is a common stationery item used to remove pencil marks from paper. It is typically made of a pliable material, such as rubber or vinyl, which is designed to abrade the surface of the paper without damaging it. The friction generated by rubbing the pyyhekumi over the pencil marks lifts the graphite particles from the paper.

The history of the pyyhekumi dates back to the 18th century. Before the invention of the rubber eraser, people used breadcrumbs or hardened bread to remove pencil marks. In 1770, English scientist Joseph Priestley discovered that rubber could effectively erase pencil marks, and thus the first rubber eraser was created. Early erasers were often large and expensive due to the cost of rubber. Over time, advancements in material science led to the development of more efficient and affordable synthetic rubber and vinyl erasers.

Pyyhekumit come in various shapes, sizes, and colors. Common types include block erasers, pencil-top erasers, and kneaded erasers. Kneaded erasers are particularly popular among artists as they can be molded into different shapes and are less likely to damage delicate paper surfaces. The effectiveness of a pyyhekumi depends on its material composition and the type of pencil lead used. Some erasers are designed for specific types of pencil marks, while others are more versatile.