A paper cut is similar to a cut with a razor blade, with one major difference. A razor blade makes a smooth, clean incision in the skin, leaving behind few if any foreign particles that might cause the wound to become infected. Although it might hurt initially, the pain brought on by a small razor cut usually fades after a few minutes. Like a superficial cut by a razor blade, a paper cut smoothly parts the skin. But while a clean razor leaves little behind to irritate the wound, a paper cut deposits material that really stings.
Paper is made of pressed wood mulch and a variety of chemicals.
When paper cuts into the skin, chemical-coated fibers as well as bacteria and tiny particles remain in the wound and stimulate pain receptors in the skin. Because the cut is usually small and shallow, the skin on either side of the wound closes quickly, trapping the fibers and other particles inside. The result is a good deal of pain, and since the closed wound doesn't allow for much bleeding, the pain seems entirely out of proportion to a cut that you can barely detect. So the next time you get a paper cut, remember this Moment of Science. It won't help dull the pain, but at least you'll know what's causing it.