Which medium is known for being transparent?

Watercolor is known for being transparent primarily because of its composition and the way it interacts with light. The pigments used in watercolor are often finely ground and suspended in a water-soluble binder, allowing light to pass through the paint layers, reflecting off the paper underneath. This transparency creates luminosity and depth in the color, enabling artists to build layers and achieve a variety of effects, from washes of color to fine details.

In contrast, oil paint tends to have a more opaque quality, especially when used in thicker applications. Though it can achieve some transparent effects with glazes, it typically doesn't retain the same inherent transparency as watercolor. Acrylic paint can be made transparent by using water or mediums that dilute it, but on its own, it is more opaque than watercolor. Pastel, while it can produce vibrant colors, is also generally opaque and relies on layering and blending for its visual effects. Thus, watercolor stands out as the most transparent medium among the options provided.