Paints change colour and fade unless they are proven to be stable. Good quality paint will keep it's beauty and last longer. Some pigments have an ability to fade over a period of time. Using paints containing these pigments results in discoloration and reduction of saturation in a painting. It is better to use stable pigments that can last unchanged for centuries. These paints contain chemicals that have been thoroughly researched.
Oil paints have been around since the time of the Renaissance, 12th-14th century. Acrylics came to be invented in the 20th century. The difference between these paints is their medium. Linseed oil is mixed with powdered pigment to produce oil paint. Acrylic polymer emulsion has been introduced since the mid 1900 and it binds a dry pigment powder. Even though acrylics are relatively new, they've been perfected by the industry. Today acrylic paintings are by no means inferior to oil paintings.
Chemical properties of the pigments and paint application are largely responsible for a good quality end result. Applying thin coats of paint first and then building the layer up thicker is mandatory when creating a painting. The bottom coats need to dry quicker than the top layers in order for the paint not to crack. Sometimes artists use this knowledge to produce crackled surface in their work. Mixing of water and oil based paints will create cracks and quick deterioration of the painted surface.
In order to produce a piece of a lasting quality it is required for the paint coats to dry. Varnishes are used to give the paintings various degrees of gloss or matt finish. It is OK to varnish an acrylic painting soon after it has been completed since acrylics are water soluble and are fast drying. Oils however dry slower. Linseed oil has to go through 8 - 12 months solidifying process. If varnish was applied to a dry to touch oil painting right away, it will fuse with the paint and will become permanent. Varnish creates a nice finish ion an artwork but it's longevity is short. It yellows due to it's chemical composite and it wears off from dust, sunlight and climate conditions. Old coat of varnish needs to be removed and fresh one applied every 30 - 50 years.
by Maxim Grunin MFA
