Markers, or felt-tip pens, serve a variety of functions. Children use them to make bright, colorful drawings. The stereotypical teacher uses a glaring, unmistakable red felt-tip to grade papers. Retail employees, roadside vendors, performers, and protestors rely on the indelible, eye-catching shades and thick inking surface of these writing and drawing utensils to announce sales, prices, and productions, or to create strongly worded posterboard signs to convey dissatisfaction. Markers are also useful for permanently marking surfaces, which is often necessary for identification purposes--putting names on clothing tags, boxes, and tape which can be adhered to almost any item.

The felt-tip pen was invented by Sidney Rosenthal in 1953. This inventor from Richmond Hill, New York, placed a felt tip on the end of a small, stout bottle of permanent ink and discovered that the resulting marks saturated a heavy, absorbent surface, yielding rich color and permanence.

The felt-tip pen...