What Is the Rosin Bag Used for in Baseball? (Explained)

A. Coatess

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A. Coatess



Sean Hunter

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what is the rosin bag used for in baseball

If you frequently watch Major League Baseball, have you ever wondered what that small canvas bag sitting by the pitcher’s plate is? It’s called a rosin bag and is filled with a white, powdery substance.

But what is the rosin bag used for in baseball, really? Simply put, it helps pitchers get an excellent grip on the ball by keeping their hands dry.

Gymnasts, weightlifters, bowlers, rock climbers, and tennis players also use rosin powder to enhance their performance.

What Is Baseball Rosin Made of?


Baseball rosin is made of pine resin and magnesium carbonate. Pine resin is extracted from the sap of fir trees. When combined with magnesium carbonate, it forms a white, chalk-like powder that helps dry sweat from the pitcher’s hands.

Often referred to as powdered pine tar, baseball rosin must not be confused with plain pine tar that hitters use to improve their grip on baseball bats.

Also, take note that a baseball rosin bag is typically made of canvas. There is a good reason behind this—the material helps keep the rosin powder dry by wicking moisture out of the bag.

Why Do Pitchers Use Rosin?

Pitchers practically dictate much of how a baseball game goes. In fact, you’ll often hear the timeless “Pitching wins championships” adage every MBL season. That is why both professional and amateur pitchers find rosin powder indispensable.

A pitcher’s position demands an enormous level of focus and precision. The defense won’t stand a chance if a pitcher keeps throwing pitches that return successful hits, especially those with high exit velocities.

Throwing strikes that are difficult for batters to hit is what matters most to pitchers.

For this reason, they need a good grip and total control over the ball. Rosin powder helps pitchers keep their hands dry to prevent the ball from slipping when they get sweaty.

Baseball rosin also helps pitchers aim the ball where they like. The chalk-like substance can even help power up the spin rate of their pitch. A higher spin rate alters the ball’s trajectory and makes it more daunting to hit.

When Was Rosin First Used in Baseball?

Rosin was first used in a baseball game in 1887. Another team was also reported to have used rosin in 1893 when the ball kept getting slippery during play.

Prior to that, pitchers simply cover their hands with dirt in an apparent attempt to get a better grip on the ball.

Around that time, baseball teams were also known for using ploys to gain an advantage over their opponents.

Among these was pouring soap and water on the soil surrounding the pitcher’s mound, so the opponent gets slimy hands when using dirt to pitch the ball.

In 1919, baseball officials decided to employ more rigid measures to maintain fair play and banned the use of foreign substances, including rosin. But this didn’t stop pitchers from sneaking rosin into the field using their pockets, handkerchiefs, and caps.

If Rosin Was Banned, Why Are Rosin Bags Still Used Nowadays?


The ban on rosin in baseball was short-lived and eventually lifted after a few years. The National League allowed the return of rosin in 1925, while the American League lifted its restriction in 1931.

Pitchers have used a host of other sticky stuff on their hands to improve ball grip and pitching performance. These include wax, syrup, petroleum jelly, paste and Band-Aids.

Spider Tack is also a popular industrial glue that has been used for the same purpose.

It’s a good thing that more stringent guidelines regarding the use of foreign substances in Major League Baseball (MLB) have been drafted over the years. Among all items mentioned, rosin powder remains the only legitimate grip enhancer that can be used.

In addition, clear-cut procedures have to be observed and implemented when using rosin bags during professional baseball matches. Let’s take a look at what the MLB specifies.

What Rules Govern the Use of Rosin Bags in MLB?

Year in and year out, professional baseball organizations encounter repeated instances of collected baseballs bearing sticky, colored markings.

They believe pitchers apply tacky substances as a measure to intensify their spin rates.

Higher strikeout rates and a decrease in offensive play also characterize the rampant use of illegal, grip-enhancing foreign substances. This has compelled league organizers to crack down on the controversy.

Here is a quick rundown of current MLB rosin bag rules:

  • Only umpires are allowed to carry the official rosin bag.*
  • Placing the rosin bag on the ground behind the pitcher’s mound may only be done by the umpire-in-chief.*
  • A pitcher is only permitted to use the rosin bag for the sole purpose of applying rosin on his bare hand/s.
  • The pitcher or any other player shall not apply rosin from the bag directly on the ball.
  • The pitcher or any other player is not allowed to apply rosin from the bag to their glove.
  • The pitcher or any other player may not dust any section of their uniform with the rosin bag.
  • A pitcher may only use the rosin bag when time is called.
  • A pitcher must step off the pitcher’s mound to use the rosin bag.
  • The ball remains in play any time it hits the rosin bag.
  • In case it rains, or when the field is wet, the pitcher may place the rosin bag in his hip pocket upon directives from the umpire.
  • All pitchers are subject to umpire checks for substances on their hands or uniforms throughout a game.

(*Prior to 2020, a single official rosin bag was used on the field for MLB matches. This has been modified due to the Covid-19 pandemic. Rules now allow each pitcher to have their own rosin bag, which they carry every time they step in and out of the field.)

Sanctions for violating MLB rosin bag rules range from official warnings and immediate ejection from the game to temporary suspensions and progressive discipline for repeated offenders.


The modest baseball rosin bag remains a basic necessity for every pitcher on the field. For over a century, it has significantly helped pitchers improve their grip on the ball by absorbing sweat and keeping their hands dry.

We hope this article has provided you with clear answers to the question, “What is the rosin bag used for in baseball?” Feel free to share this post with anyone who is still in the dark as to what that little package behind the pitcher’s mound is for.

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