Oil painting dates back for centuries and is an incredibly far-reaching artistic practice. It is the process of painting with pigments with a medium of drying oil as the binder. Oils are beloved by artists for many reasons. They can be very opaque, or they can be thinned with a solvent to varying levels of transparency. They have a slow-drying time, during which their colors do not change, allowing the artist to rework, correct, and even scrape off areas of paint. Commonly used drying oils include linseed oil, poppy seed oil, walnut oil, and safflower oil.