If oil paint was just now being invented, and had to sell itself to the marketplace as a new medium, it would probably have an incredibly difficult time – especially if we knew beforehand that its list of problems would include yellowing, cracking, wrinkling, flaking, embrittlement, hydrolysis, fatty acid crystallization, protuberances and delamination caused by metallic soaps, and even cases where some oil paints are liquefying after being seemingly stable for decades. This is not to say acrylics do not have their own challenges as well! The softness of the acrylic system makes it easy for dirt and dust to become embedded in the surface, for acrylic layers to easily stick to other materials, and for textures to be imprinted into the surface when things are pressed against them (especially in a warm environment.) And there are known difficulties with surfactant migration and challenges with cleaning. Ultimately deciding which medium is more durable is like the proverbial one comparing apples and oranges – for all their overlap, the two remain distinct, with their own list of strengths and weaknesses. Nevertheless the question is a common one and we wanted to take a moment to share some thoughts and point to a few resources one can go to.
In terms of lightfastness, oils and acrylics largely draw from the same pigments, which are then tested using the same procedure laid out in ASTM D4303, Standard Test Methods for Lightfastness of Colorants Used in Artists’ Materials. So from the standpoint of lightfastness there is little difference to be concerned about as long as the colors you are using have ASTM lightfastness ratings.
As for an actual document that lays out the differences in durability between acrylic and oils, there are very few that compare artist oils and acrylics directly but will rather focus now on one, now on the other, and often around very narrow subject areas. That said, the following article written by a very prominent researcher in Materials Science, Dr. Frank Jones, gives an excellent general overview:
Aspects of Longevity of Oil and Acrylic Artist Paints
https://justpaint.org/aspects-of-longevity-of-oil-and-acrylic-artist-paints/
As the above point outs, acrylics have proven advantages in terms of resistance to yellowing and long term flexibility, while the harder surface of oil paints provides clear advantages in terms of cleaning and solvent resistance.
Here are also a few articles that detail some of the challenges acrylics face in conservation, as a way to balance the generally held belief that, given everything, acrylics should prove the more durable system over the long term:
Conservation Concerns for Acrylic Emulsion Paints: A Literature Review
http://www.tate.org.uk/download/file/fid/7414
Conservation of Acrylic Paintings
https://justpaint.org/conservation-of-acrylic-paintings/
Defining the Acrylic Patina
https://justpaint.org/defining-the-acrylic-patina/
As one can imagine, the literature speaking to the problems conservators encounter with oil paints is simply too vast to go into here, and few people realize that our sense of oil paints doing well over a long period of time is due to a virtual army of professionals who work full time to maintain, repair, and restore the works that we see in museums.
In the end, while one can easily draw up these types of lists contrasting the weaknesses and strengths of oils and acrylics, it’s important to also celebrate the fact that the two mediums are truly different and allow for unique forms of expression and ways of working. Both have been central to the production of some of the finest and most important artworks we know, and as a company we are ultimately dedicated to supporting each of them with a sense of passion and love for the materials all artists depend on for their creativity.
