Before the 19th century, artists mixed their own paints, which allowed them to achieve the desired color and thickness, and to control the use of fillers. While suitable media and raw pigments are available for the individual production of acrylic paint, hand mixing may not be practical because of the fast drying time and other technical issues, such as the necessity to combine several polymers.
Acrylic painters can modify the appearance, hardness, flexibility, texture, and other characteristics of the paint surface by using acrylic mediums or simply by adding water.
Watercolor and oil painters also use various mediums, but the range of acrylic mediums is much greater. Acrylics have the ability to bond to many different surfaces, and mediums can be used to modify their binding characteristics.
Acrylics can be used on paper, canvas and a range of other materials; however, their use on engineered woods such as medium-density fiberboard can be problematic because of the porous nature of those surfaces. In these cases it is recommended that the surface first be sealed with an appropriate sealer.
Acrylics can be applied in thin layers or washes to create effects that resemble watercolors and other water-based mediums. They can also be used to build thick layers of paint—gel and molding paste are sometimes used to create paintings with relief features. Acrylics are used for this purpose because they easily scrape or peel from a surface.