To bring out the best attributes of letterpress, printers must understand the capabilities and advantages of what can be a very unforgiving medium. For instance, since most letterpress equipment prints only one color at a time, printing multiple colors requires a separate press run in register with the preceding color. When offset printing arrived in the 1950s, it cost less, and made the color process easier. The inking system on letterpress equipment is the same as offset presses, posing problems for some graphics. Detailed, white (or "knocked out") areas, such as small, serif type, or very fine halftone surrounded by fields of color can fill in with ink and lose definition if rollers are not adjusted correctly. However, a skilled printer overcomes most of these problems. However, a letterpress provides the option of a wider range of paper, including handmade, organic, and tree-free. Letterpress printing provides a wide range of production choices. The classic feel and finish of letterpress papers takes printing back to an era of quality and craftsmanship. Even the smell of the ink, more apparent on a letterpress-printed page than with offset, may appeal to collectors.