Evidence suggests that adhesion is rarely the issue when using oils over a wide range of acrylic products, and most oil paints should adhere well to the majority of our gels, paints, and mediums. Almost all acrylic paint films, regardless of sheen, are still porous enough to allow oils to penetrate sufficiently and form a reasonably strong bond. The real concern with oils is their tendency to crack as they become increasingly brittle and inflexible with age. This is true regardless of whether the oils are on top of acrylics or more traditional materials. Because of this, we do not recommend using oils over a very thick application or texture, of any material, without some concern. The reason is that these materials will likely change over time, as well as expand and contract in response to the environment, at a different rate then the more fragile oils can accommodate. Ultimately it is these factors, rather than the use of acrylics per se, that leads to the potential of cracking.
A significant body of research in conservation science, and more than 40 years of actual use, has repeatedly proven that high quality acrylic gesso provides excellent adhesion for oil paints and can be considered a fully archival and suitable ground for oil painters to work on. Golden makes several grounds that are appropriate for this purpose, including:
To lessen these risks, while also maximizing adhesion, we strongly recommend the following guidelines:
- Work on inflexible supports whenever possible. Rigid panels are better than flexible supports like canvas in reducing the amount of movement over time. If you cannot work on a panel consider mounting the canvas to a rigid support afterwards, or take steps to make the canvas stiffer. For more information please see the following Tech Sheet:
Preparing a Painting Support:
- Make sure all acrylic materials are completely dry and fully cured beforehand. This can mean several days or weeks depending on the thickness of the application and the environmental conditions
- Maintain a matte surface. Because the adhesion of oils to acrylics is purely mechanical, they will develop maximum adhesion when applied to porous, toothy, and matte surfaces. In terms of color, our Highloads, Matte Acrylics, or Matte Fluid Acrylics provide ideal surfaces for the oil paint to anchor itself to. Likewise, our Matte Mediums, Pumice Gels, Coarse Alumina Gel, Molding Paste and Hard Molding Paste also provide a sufficiently toothy surface. For additional information, please consult the following pages:
High Load Acrylics
- Avoid using over soft, spongy materials. Products such as our Light Molding Paste and Crackle Paste are too soft or fragile to provide a solid and stable ground for the oils. Some restrictions also apply if using our Absorbent Ground. Please consult its Tech Sheet for further information:
- Keep in a stable environment.This can play a critical role in minimizing possible cracking. Try to avoid large changes in temperature and humidity, and limit the amount of shipping and movement.
- Avoid rolling or flexing when possible. Rolling and flexing places a lot of stress on the surface of the painting and the differing degrees of flexibility between oils and acrylics could further add to those risks.
The above information is based on research and testing done by Golden Artist Colors, Inc., and is provided as a basis for understanding the potential uses of the products mentioned. Due to the numerous variables in methods, materials and conditions of producing art, Golden Artist Colors, Inc. cannot be sure the product will be right for you. Therefore, we urge product users to test each application to ensure all individual project requirements are met. While we believe the above information is accurate, WE MAKE NO EXPRESS OR IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, and we shall in no event be liable for any damages (indirect, consequential, or otherwise) that may occur as a result of a product application.