Why do some glove oils turn rancid? Why is that important to know?

Why baseball glove oils go rancid

Oils can go rancid because they contain unsaturated fatty acids. These fatty acids have double bonds in their chemical structure, which makes them susceptible to oxidation. When unsaturated fatty acids react with oxygen, they form compounds that have unpleasant odors and off-flavors. Beyond the obvious, this oxidation process can degrade the leather shortening it’s useful life.

• Indicator or test of an oil's potential for rancidity

The iodine value is a measure of an oil's potential for rancidity. The higher the iodine value, the more unsaturated the oil is and the more likely it is to go rancid. Neatsfoot oil, for example, has an iodine value of 75, while coconut oil has an iodine value of 9 and Mitt-Spit glove oil as an Iodine value of 1. This means that Neatsfoot Oil is more likely to go rancid than coconut oil. The least likely is Mitt-Spit Glove Oil.

• Ranking of oils used to condition baseball gloves

The following is a ranking of oils used to condition baseball gloves, from least likely to go rancid to most likely to go rancid:

1. Mitt-Spit glove oil (iodine value of 1)

2. Coconut oil (iodine value of 9)

3. Beeswax (iodine value of 7)

4. Avocado oil (iodine value of 8)

5. Olive oil (iodine value of 85)

6. Neatsfoot oil (iodine value of 75)

7. Mink oil (iodine value of 80-95)

• Why it's a bad idea to use the wrong type of oil on a baseball glove

Using the wrong type of oil on a baseball glove can cause the leather to become brittle and lose its original properties. This can lead to a compromised performance, reduced durability, and a less comfortable feel for the player. In addition, rancid oils can develop an unpleasant smell, which can be both unsightly and unpleasant.

Therefore, it is important to use a high-quality oil that is designed specifically for conditioning baseball gloves. These oils are typically low in iodine value and are less likely to go rancid. They will also help to keep the leather supple and prevent it from drying out.

This alone is the reason why Mitt-Spit Glove Oil should be every baseball player’s go to product to keep their glove in tip-top shape.

Can the oils used in baseball glove conditioners turn rancid? How is the potential for rancidity measured?

As a chemist would explain, the iodine index measures the potential of oils going rancid when used on baseball gloves. Included is information about potential health effects and list some common oils used on baseball gloves along with their associated iodine index values.

When oils are exposed to oxygen in the air, they can undergo a process of oxidation. Oxidation can be accelerated by factors such as heat and light — think warm sunny day.  Oxidation leads to the formation of highly reactive free radicals, which can damage the oil and cause it to go rancid. Rancidity refers to the development of off-flavors, odors, and the degradation of the oil's nutritional value to the point that it can make a person feel ill. 

Technically, the iodine index is a measure of the degree of unsaturation in a fatty acid or oil. Unsaturated fatty acids contain double bonds in their carbon chains, which make them more prone to oxidation. The iodine index quantifies the number of double bonds present in the fatty acids or oil.

In the context of baseball gloves, oils are used to condition and preserve the leather. The natural oils in the leather can gradually dry out and deteriorate over time, leading to stiffness and cracking. Conditioning oils are applied to replenish the lost moisture and maintain the flexibility and durability of the leather. However, if the oil used has a high iodine index, it indicates a higher level of unsaturation and greater susceptibility to oxidation/rancidity.

When an oil with a high iodine index is applied to a baseball glove, it can oxidize more readily upon exposure to air and sunlight as happens throughout the baseball season. This oxidation process can lead to the formation of undesirable compounds, including aldehydes, ketones, and peroxides, which contribute to the rancid odor and health concerns. The glove may become sticky, greasy, or develop a foul smell, making it less pleasant to use.

Moreover, from a health perspective, rancid oils can have adverse effects. Consuming rancid oils can cause gastrointestinal discomfort, including nausea, diarrhea, and vomiting. Inhaling the unpleasant odors from rancid oils may also cause respiratory irritation and discomfort.  The greatest concern is with children.  If you watch a child with a glove in their hand during slow times of a game, they often put the glove to their mouth.  If the oils used to condition the glove have gone rancid, it could make the child sick.

Here are some commonly used oils on baseball gloves, along with their associated iodine index values:

1. Neatsfoot Oil: Iodine Index around 84-88

2. Mink Oil: Iodine Index around 87-91

3. Lanolin Oil: Iodine Index around 88-92

4. Coconut Oil: Iodine Index around 10-20

5. Olive Oil: Iodine Index around 75-94

6. Almond Oil: Iodine Index around 93-105

7. Mitt-Spit Glove Oil: Iodine Index of around <1-1

Clearly, the safest Glove Oil is the one with the lowest Iodine Index - Mitt-Spit Glove Oil. It's important to note that these values may vary slightly depending on the specific brand or source of the oil. Choosing an oil with a lower iodine index generally indicates a lower susceptibility to oxidation and a reduced risk of rancidity.

When selecting oils for conditioning baseball gloves, it's recommended to opt for oils with lower iodine index values to minimize the chances of rancidity and ensure the longevity of the glove's leather.

What's the Iodine Index and why is it important

We know it’s important to properly apply oil or conditioners to leather.  What’s also important to know which oils are good for leather and which can go rancid. Have you ever heard of the iodine index? This measurement is used to determine the potential for rancidity in oils, which is an important factor to consider for health reasons.

The iodine index, sometimes called the iodine value, is a measure of the unsaturated fatty acids present in an oil which determines the oil’s potential for rancidity. Unsaturated fatty acids contain double bonds between carbon atoms, which can become rancid when exposed to oxygen and heat. The iodine index is determined by adding iodine to the oil, which reacts with the double bonds to form a complex that can be measured.

The higher the iodine index, the more unsaturated fatty acids are present in the oil. This means that the oil is more susceptible to oxidation, which leads to rancidity. Rancidity is characterized by a stale, unpleasant, unhealthy odor.  I’m sure you’ve seen young boys and girls standing in the outfield totally bored and literally putting their mitt in their mouth.

Different oils have different iodine indexes, depending on their composition. For example, coconut oil has a very low iodine index of around 10, which means it contains mostly saturated fatty acids and is less prone to rancidity. On the other hand, soybean oil has an iodine index of around 130, indicating that it is high in unsaturated fatty acids and more prone to rancidity. 

It's important to note that not all unsaturated fatty acids (oils) are created equal. Neat’s-foot oil has a value of about 72.  Mink oil runs about 88.  Mitt-Spit Glove Oil has an iodine index of about 1.  Making Mitt-Spit Glove Oil by far the safest to use to prevent rancidity.

The iodine index is an important measurement for assessing the potential for rancidity in oils. Oils high in unsaturated fatty acids are more susceptible to oxidation, which leads to rancidity. By choosing oils with lower iodine indexes, we can reduce the risk of rancidity and enjoy healthier lifestyle.