Why is oil used on tack?

The use of oil on tack primarily serves the purpose of conditioning the leather, making it supple and helping to waterproof it, especially when the leather has become dry or cracked. Leather items, such as saddles and bridles, can lose moisture and flexibility over time due to environmental factors, such as exposure to sunlight and varying humidity levels.

Oiling the leather replenishes its natural oils, enhancing its durability and preventing it from becoming brittle, which can lead to cracks that compromise the structure and safety of the tack. Additionally, treating leather with oil can create a barrier that helps repel water, which is crucial in protecting the tack from damage in wet conditions.

While the other given options may touch on aspects of care for tack, they do not address its primary purpose as effectively as the correct answer does. For instance, while oil can contribute to a shiny appearance, that is not its main purpose. Similarly, cleaning dirt and debris or addressing odors are more aptly targeted by specific cleaning products rather than oil itself.