painting Painting is a Visual arts, visual art, which is characterized by the practice of applying paint, pigment, color or other medium to a solid surface (called "matrix" or "Support (art), support"). The medium is commonly applied to the base with ...

, a retarder is a substance, usually a glycol and usually added to

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

, that is used to slow the drying time of

acrylic paints Acrylic paint is a fast-drying paint made of pigment suspended in acrylic polymer emulsion and plasticizers, silicone oils, defoamers, stabilizers, or metal soaps. Most acrylic paints are water-based, but become water-resistant when dry. Depe ...

, giving more time for blending or layering highlights.

Use in fine art

Retarders are used to counter the fast drying properties of acrylic paints, making possible the usage of wet-on-wet or other techniques which would otherwise require

oil paints Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. Oil paint also has practical advantages over other paints, mainly because it is waterproof. The earliest surviving ex ...

. When used correctly, they can keep the paint wet from half an hour extra to a full day's working time. Applying too much retardant, however, can prevent a layer from drying correctly for as long as the retardant is present, causing future damage to the painting unless the affected layer of paint is removed or re-mixed.

Content

They generally contain glycol (such as

propylene glycol Propylene glycol ( IUPAC name: propane-1,2-diol) is a viscous, colorless liquid. It is almost odorless and has a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH. As it contains two alcohol groups, it is classified as a diol. An al ...

), or glycerin-based additives.

Home-Made

For home-made acrylic retarder, water

glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...

down about 5:1 (water: glycerol) and apply to paint.

References

Painting materials {{art-material-stub