Baseball pitchers use a rosin bag to help them get a better grip on the baseball. A slippery baseball is a major obstacle to throwing a good pitch of any type. When the umpire hollers "Play ball", you can be sure that the pitcher has the rosin bag on the pitching mound with him.

Rosin is the primary byproduct of heating the resin of mostly pine trees. The residue is hard and flaky, and has a high content of abietic acid. The resultant rosin enhances friction, and is used for a variety of purposes. Everyone is familiar with the violinist who rosins his bow before playing his instrument. The rosin applied to the hair of the bow increases the friction between the bow hairs and the strings, necessary to make the instrument speak.

In the case of baseball pitchers, the rosin serves to counteract the perspiration that would cause him to lose his grip. The friction provided by the fingertips is what causes a ball to have the properties of a curve ball, slider, and other varieties of pitches. Additionally, wet weather conditions would make pitching almost impossible were it not for rosin.

The next time that you go to a ball game, you will know that when the pitcher picks up that little bag that it's not just his nerves. Nor is it a little toy for pitchers to distract themselves with. It is one of the tools of the trade for a baseball pitcher.

Learn more about this author, Bob Schmidt.
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