A kneaded eraser, also commonly known as a putty rubber, is a tool for artists. It is usually made of a grey or white pliable material, such as rubber (though it can be found in many different colors, ranging from green, blue, hot pinks, yellow, and many other colors) and resembles putty or chewing gum. It functions by absorbing and "picking up" graphite and charcoal particles, in addition to carbon, colored pencil, or pastel marks. It does not wear away nor leave behind eraser residue, thus it lasts much longer than other erasers.
Kneaded erasers can be shaped by hand for precision erasing, creating highlights, or performing detailed work. They are commonly used to remove light charcoal or graphite marks and in subtractive drawing techniques. However, they are ill-suited for completely erasing large areas, and may smear or stick if too warm.
Although kneaded erasers do not wear away like other erasers, they can become saturated and unable to absorb any more graphite or charcoal. In that case a kneaded eraser will actually leave marks on the paper instead of erasing them.
Kneaded erasers also do not leave any eraser crumbs like other erasers.
Different colored erasers can be blended together, creating a larger eraser that is a new, unique color. New kneaded erasers can be stretched and compressed easily, changing their texture and form.
Kneaded erasers are also useful for making impromptu sculptures to sketch from. Kneaded erasers are mostly used for slightly, but not fully, erasing the content of graphite. It has great plasticity and can be molded and shaped into desired forms for ease of usage.
Kneaded erasers are also preferred because they are easy to clean. You simply knead your kneaded eraser and the medium will fade into the eraser.