I have wondered for many years how some of my creations will age. I use acrylic paint on a number of them and the aging process never seemed to be discussed by artists or manufacturers. Maybe they did talk about this subject but I never seemed to fall across those discussions. Finally I started to try gathering information and the results are really quite interesting for anyone painting in acrylics or owning acrylic paintings.
The behaviour of oil paints has been relatively well understood because mixing oils with pigments has been used for over a 1000 years and we have seen what happens to oil paintings over this time. Water-based acrylics paints for artists started to appear in the 1950s and so we have had little time to see and understand how age changes these paints.
Water-based acrylics paints are not soluble in water once dried. They are not as hard as oil paints at room temperatures and the softer acrylic paint holds onto dust and dirt and may even slowly flow around particles. Worse than this, they are not electrically conductive and so can build up static charge which attracts dust and dirt. It has been suggested that if a painting is kept indoors it takes around 50 years before the dirt accumulating on the painting surface is noticeable. No ideal solutions have been found so far to cleaning acrylic paintings. Traditional protective varnished used on oil paints can’t normally be used on acrylic paints as the varnish will dissolve the acrylic. Keeping paintings behind a glass protective frame would appear to be the best way to keep dust and dirt from paintings. These paints become very soft above 60 deg C and even at room temperature the paint may be dented or abraded if pressed. Temperature and humidity need to be kept low otherwise mould growth may start. Acrylic paints are more flexible than oil paints and so crack less easily although when exposed to sub-zero temperatures they do become brittle and will crack. Ultraviolet light fades the pigments in cheaper acrylic paints.
Manufacturers have changed the formulation of acrylic paints over the years and this has made research into the aging process and identifying conservation processes difficult.
Bubbles, pinholes, oxidation, haze… If you are interested in reading more (and there is a lot more!) have a look at the following links:
All worth thinking about if you use acrylic paints!