Oil-based ink is a type of printing ink made primarily from pigments suspended in oil, often derived from plants or petroleum. This ink is known for its rich colors and durability, making it suitable for various printing methods, including offset printing and letterpress. One of the key characteristics of oil-based ink is its slow drying time, which allows for better blending and layering of colors. However, this can also lead to smudging if not handled properly. Oil-based inks are commonly used in commercial printing and fine art applications due to their vibrant finish and long-lasting results.