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Rosin Bag: What Is It Used For In Baseball?

Written by Chris 

Published on February 22, 2024

It's no secret that pitchers rely on a good grip to be successful on the mound. If you've ever been to a professional or minor league game, you maybe wondered what that small white bag on the back of the pitcher's mound was. Well, they call it a rosin bag, and pitchers have used them for years to improve their grip on the baseball. However, many pitchers believe that the rosin bag isn't enough to create a proper grip on the baseball. This is why they've turned to other substances, such as sunscreen and pine tar.

What Is A Baseball Rosin Bag?

In baseball, a rosin bag is a small cloth sack filled with rosin powder that pitchers use to improve their grip on the baseball by drying moisture from their hands. The use of rosin bags became common in the early 20th century, though rosin itself has been used in various forms for longer. Originally, pitchers would rely on sweat, dirt, or rubbing baseballs on their clothing to get a better grip. The introduction of the rosin bag provided a more consistent and practical way to maintain control of the ball, especially in humid or sweaty conditions.

Why Do Pitchers Use Rosin?

Rosin bags are a familiar sight on the pitcher's mound, and every pitcher has their own way of using them. Some pitchers apply rosin to their entire hand, while others focus on their fingertips. Interestingly, some pitchers will lick their fingers before using the rosin, believing it helps the powder stick better to their skin.

 

Though primarily used by pitchers, the rosin bag can also benefit position players. Some apply it to their gloves or even bats to improve their grip. The rosin helps absorb sweat and moisture, ensuring a more secure hold on the ball or equipment.
Poster

History Of The Rosin Bag

The rosin bag was introduced in baseball in the late 19th century, giving pitchers a reliable way to improve their grip using powdered pine resin. In 1919, Major League Baseball started cracking down on foreign substances, which led to debates over the use of rosin. Ultimately, the National League reintroduced the rosin bag in 1925, and the American League followed in 1931. The bag’s main purpose has always been to absorb moisture, helping pitchers keep their hands dry and improving grip.

 

Before the standardized rosin bag, pitchers would often use loose rosin or stash small amounts in their pockets. To streamline its use and provide better oversight, the bag was introduced and placed on the mound.

 

Today, it’s rare to see a pitcher take the mound without using the rosin bag a few times during a game. Umpires now inspect the rosin bag as part of the equipment check before games.

 

Recent Incidents Involving Rosin Bags in Baseball

The use of rosin bags in baseball has been a longstanding practice, but recent incidents have brought renewed attention to its application and potential misuse:

Cardinals' Giovanny Gallegos Incident: During a game, Cardinals reliever Giovanny Gallegos was approached by umpires after he applied rosin to his left arm. The umpires, concerned about the potential for foreign substances, wiped down Gallegos' arm to ensure compliance with league rules.

Max Scherzer's Ejection: In a game between the Mets and the Dodgers, right-handed pitcher Max Scherzer was ejected after umpires found his hand to be unusually sticky. Scherzer, defending himself, insisted that he only used sweat and rosin. This incident sparked significant debate, especially given the enhanced enforcement of foreign substance rules introduced for the 2023 season. The rules explicitly state that rosin cannot be applied to the glove and that its misuse could be considered as using a foreign substance.

Domingo Germán's Rosin Controversy: During a game between the Minnesota Twins and the New York Yankees, starting pitcher Domingo Germán was involved in a rosin-related controversy. Umpire James Hoye noticed excess rosin on Germán's hands and asked him to clean them. Despite Germán's compliance, the tackiness remained, leading to further discussions on the field. While Germán was not ejected, Twins' manager Rocco Baldelli was, after expressing his disagreement with the umpire's decision not to eject Germán.

How Are Rosin Bags Made?

Manufacturers produce rosin powder by extracting sap from pine or fir trees during spring and boiling it to remove turpentine. The process leaves behind a dense, hard resin that manufacturers either leave as-is or grind into a powder.

Where Does Rosin Come From?

After the recent controversy over foreign substances in MLB, the league has really tightened the rules. Now, pitchers can't have anything on them when they come to the mound, and umpires are doing regular checks. If they find anything suspicious, the pitcher gets ejected right away.

 

To further control the situation, MLB introduced new regulations, including placing humidors in all 30 ballparks to keep the baseballs' moisture levels consistent. This helps ensure the balls behave the same, no matter where the game is played.

 

On top of that, teams can no longer choose their own rosin suppliers. Before, they could buy from any company, and there wasn't much oversight. Now, MLB has partnered with Pelican Bat Wax, a small company out of San Francisco, to be the league’s exclusive supplier for rosin bags. While some pitchers aren’t thrilled with the changes, MLB hopes these steps will level the playing field and cut down on the use of illegal substances.

Rosin In Baseball - MLB Rules

Since the game's integrity is extremely important, MLB created new guidelines around foreign substances that all teams would have to adhere to. The new rules state that if pitchers use foreign substances to manipulate the baseball, officials will eject and suspend them for ten games.


Pitchers would also be subject to mandatory inspections by the umpire during the game. The reason for these new guidelines was that pitchers have been using foreign substances like spider tack that significantly improve their performance.


It was no longer about getting rid of the sweat or improving the grip among pitchers. Fans want to see home runs, but these foreign substances increased the number of strikeouts and no-hitters. The equivalent would be allowing hitters to use metal bats at the plate. 

The rules around rosin bags state that:

Umpires must review the rosin bag and game balls before each game

Only the umpire can place the official rosin bag on the back of the mound before the game

The pitcher can only use rosin on his hands

Cannot apply rosin directly on the ball

Cannot use the rosin bag on their glove

Cannot use the rosin bag on their uniform

The pitcher can only use the rosin bag when the umpire calls time and they step off the mound

If it's raining, the pitcher may place the rosin bag in their pocket at the discretion of the umpire

MLB prohibits all substances except for rosin

Players may not intentionally/unintentionally combine other substances with rosin. This includes things like sunscreen. Doing so can result in ejection and suspension

Pitchers cannot use sunscreen during night games in closed-roofed parks

If a live ball hits the rosin bag, it is still considered to be in play

Final Thoughts

As a pitcher, you're always searching for that little extra edge, something to help you gain better control of the ball. For many, that edge comes in the simple form of rosin.

 

Whether it’s in the minor leagues or the majors, rosin powder—made from pine tree resin—helps pitchers keep their hands dry and improve their grip, especially in tough conditions like hot, humid weather. In the big leagues, it can mean the difference between nailing a perfect pitch or letting one slip down the middle. Either way, it remains an important tool for pitchers who want every advantage they can get.

Frequently Asked Questions

What is rosin used for in baseball?

A rosin bag helps pitchers improve their grip on the ball by absorbing moisture from their hands.

How do resin and rosin bags differ?

Resin is sticky, while manufacturers make rosin as a dry powder from pine sap.

Are rosin bags tacky?

No, rosin bags contain a dry powder that absorbs moisture, rather than providing stickiness.

Is using rosin permitted in MLB?

Yes, MLB allows pitchers to use rosin bags, but they must adhere to specific guidelines.

What makes rosin pricey?

The extraction process from pine trees and its demand in various industries contribute to rosin's cost.

How often do umpires inspect pitchers for rosin misuse?

Umpires can inspect pitchers at their discretion, especially if there's suspicion of rule violations.