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Acrylic or Watercolor Underpainting for Oils

Canvas sized with acrylic Fluid Matte Medium, then painted with tinted GAC 800, Heavy Gel Matte and High Flow Acrylics. Oil paint brushed onto right hand side for varied texture, density of color and surface sheen.

 

Acrylic Underpainting

Acrylics under oil is nothing new. For half a century artists have confidently used acrylic gesso to prepare their raw canvas and panels for oil painting. So why not use a couple additional layers of acrylic to establish your design or build up texture? Acrylics have a wide range of consistencies and can be used as a ground, to tone a surface or make a grisaille underpainting. Unlike oil paints, that have variable dry times based on the pigment, the entire palette of acrylic colors dry at the same rate and are suitable for use in an underpainting. For those who might be concerned about the structural stability of oils over acrylic, for 30+ years we have been testing oil paint over water-based acrylics and have never seen any issues with adhesion or incompatibility. For an in depth look at this topic, see Using Oils with Acrylics. Keep in mind, that oils can be used over acrylics, but acrylics are not compatible over oil paints. Additionally, here are a few things to consider when using oils over acrylics:

Protect natural fiber substrates from oil penetration with at least 3 coats of acrylic gesso or 2 coats of acrylic medium. It is important to block oil from soaking into canvas, linen and paper because it can prematurely deteriorate the natural fibers. Examples of acrylic mediums to use for this purpose are GAC 100, Fluid Matte Medium or Matte Medium to name a few. While wood substrates are not damaged by oil penetration, sizing them will reduce their absorbency and provide an additional barrier between the wood and the painted layers.

Allow acrylic layers to dry fully before painting on top with oils. Even thin layers of acrylic can take up to 3 days to fully dry. We recommend waiting this amount of time after your final layer of acrylic before beginning your oil painting, and even longer if the layers are thickly applied. This also includes Acrylic Gesso or acrylic sizing.

Refrain from using soft or spongy acrylics as a ground or in an underpainting. Acrylics stay flexible indefinitely, where oils become increasingly brittle over the decades. A soft and spongy acrylic underpainting, especially if applied with any thickness, may put oil paint layers at risk of cracking if the surface is ever flexed. GOLDEN Light Molding Paste and Crackle Paste are examples of soft and spongy materials to avoid for this purpose.

Stay away from sharp peaks and textures. This relates to the above statement. Even gels and pastes that become quite rigid when dry, can soften with increased temperatures and become flexible if applied in dollops, pointy mounds or ridges. Again, this may not be a concern for many years, but ultimately sharp textures could flex and compromise the oil paint layers applied over top. Barring strong peaks and ridges, it may actually benefit to build texture with acrylics instead of oil paint because oils can take a very long time to fully cure when applied thickly and in some extreme cases, never fully dry.

Be aware when using highly absorbent acrylics under oil paints. Some acrylics are designed to be highly absorbent, like the GOLDEN Absorbent Ground. These materials can draw an excess of oil out of the paints applied on top, potentially leaving those layers under bound. Some oil penetration into the underlying layers is beneficial for good adhesion, but having too much oil drawn out of your paint layers can leave oil paints matte and friable with the potential for cracking or flaking. Apply washes of thinned acrylic or thinned oil colors to help reduce absorbency to make these types of surfaces acceptable for use with oil paints.

More layers = Increased stiffness. Increased stiffness provides a stable base for oil layers that will become rigid over time. This is especially important when working on flexible supports. Several acrylic layers (4+) should provide increased stiffness depending on the product and the thickness of the application.

Gloss or Matte? We have seen excellent adhesion over both, but typically matte surfaces provide more tooth for improved adhesion in any system, oils or acrylics. When possible, use matte acrylics or apply a thin layer of Fluid Matte Medium over a glossy acrylic underpainting to provide additional tooth.

 

This canvas was prepared with 4 coats of tinted pink Acrylic Gesso visible around the edge. The first layer is an acrylic underpainting (left), a layer of oil paint (center) and a second coat of oil with more color and gesture (right).

 

Watercolor Underpainting

Watercolor underpainting with 2 layers of oil paint made on oil paper. Oil paper is pre-sized to protect from oil penetration. Watercolor underpainting (left), oil paint thinned with solvent (center) and an additional layer of oil paint with added medium (right).

 

Although watercolor under oil is not a widely used technique today, it is surprisingly effective and was well known, at least in the 19th century, among British painters (Carlyle, 2001). We found that regardless of whether the watercolor was soaked into the ground or dried over a glossy acrylic surface, that oil paint, medium and/or odorless mineral spirits could be applied on top without reactivating the watercolor. We tested QoR bound in Aquazol, as well as competitor brands made with gum arabic with the same positive results. We did not test watercolor over oil grounds, but historically it was practiced after the ground was deglossed and then properly cleaned to facilitate better wetting of the surface. Artists also used to mix ox gall into their watercolor to keep their washes from beading up. A benefit of watercolor is they can be reworked even after they dry, allowing artists to perfect an underpainting or wipe back to a bright white ground to establish the lighter areas of a composition. Unlike acrylics, watercolors do not require several days to completely dry and coalesce. They should be ready to paint over after they are fully dry to the touch. Here are a couple things to consider when using this technique:

The substrate still needs to be sized to protect from oil penetration. The exception being oil paper, which is already sized and prepared for oil paints. The watercolor layers do not count as sizing. Instead, prepare the substrate as if oils will be applied directly. In most cases, using watercolor in this way essentially amounts to making a mixed media piece with acrylics, watercolor and oils. It may benefit the watercolor application if the final layer of acrylic sizing or the acrylic ground is slightly absorbent.

Do not apply the watercolor thickly. The oil needs to be able to soak through the watercolor and bind to the substrate or ground. Thick applications could interfere with this important aspect of proper adhesion.

Do not isolate the watercolor from the oil paints with MSA or Archival Varnish. We have written many articles about the benefit of varnishing watercolors so they can be displayed without glass. This is great, but should not be used for this application because oil paints are not compatible over top of MSA or Archival Varnish. For more information see Why Oil Painting Over MSA or Archival Varnish Is Not Recommended.

Options for protecting exposed watercolor. Artists in the past optionally isolated their watercolor with a dilute natural resin varnish or very thin layer of light colored drying oil applied with a sponge. Although this might benefit an area of watercolor that is left exposed, it does not seem necessary to improve compatibility between the watercolor and the oil layers. This may have served a dual purpose of reducing absorbency of the ground and locking down the water sensitive paint layer. With this historical approach in mind, it may benefit to fully cover the watercolor underpainting with oils paints or at least glaze over all exposed watercolor to protect it from the potential of lifting. Alternatively, if after the oil painting is finished and there is still watercolor exposed, it can be varnished after the appropriate waiting period. We recommend allowing oils to cure for 6 months to a year before varnishing.

Acrylic and watercolor underpainting and toning techniques can speed up the initial stages of the oil painting process. They are also great ways to remove solvents from the studio and still get thin, washy, saturated applications to work on top of. We recommend testing to see how this can benefit your studio practice and maybe even change the way you work all together! We hope these considerations will help you confidently explore this combination of materials in your future paintings. Please let us know how it goes! If you have any questions or comments, please contact our Materials and Application Department at 800-959- 6543 or help@goldenpaints.com.

 

140 pound watercolor paper sized with acrylic and prepared with Pastel Ground. Pastel Ground offers slight tooth and absorbency. Grisaille underpainting made with black watercolor and then a thin layer of oil paint to introduce color.

 

Additional resources:

Just Paint: Using Oils over Acrylics

Just Paint: Why Oil Painting Over MSA or Archival Varnish Is Not Recommended

Oil Over Acrylic Guidelines

Carlyle, Leslie, (2001) The Artists Assistant, Archetype Publications, London

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20 Responses to Acrylic or Watercolor Underpainting for Oils

  1. Joshua Simonson March 18, 2019 at 6:08 pm #

    Wow, I had no idea one could paint over watercolors with oils! I’ll have to give this a try, it might open up a whole new range of possibilities!

    • Greg Watson March 20, 2019 at 3:58 pm #

      Hello Joshua,
      It is pretty great to have such a simple solution for solvent-free, fast drying underpainting. We hope it works out well for you. Let us know how it goes!
      Take care,
      Greg

  2. Susan Sorrell Hill March 18, 2019 at 10:53 pm #

    Thanks so much for consolidating all of the relevant technical information related to using oils over water-based underpainting in one, succinct place. Much appreciated!!

    • Greg Watson March 20, 2019 at 3:54 pm #

      Hi Susan,
      You are very welcome. Glad you found it helpful!
      Greg

  3. Anne Dalton March 25, 2019 at 1:38 pm #

    Thank you Greg! Very clear blog and succinct as well. I love reading your postings.

    • Greg Watson March 26, 2019 at 4:00 pm #

      You are so welcome! Thanks for the comment!! 🙂

  4. Alan Geller March 25, 2019 at 2:43 pm #

    Great article with lots of information. You didn’t mention the advisability of acrylic on oil paint grounded canvas covered boards. These are available at reasonable cost, are very portable and mountable. They are advertised as non-adsorptive, and I wonder how that affects the acrylic adhesion?
    Any advise is appreciated.

    Alan

    • Greg Watson March 26, 2019 at 3:57 pm #

      Hi Alan,
      Appreciate it. Thanks for the question. We do not recommend this, as we have not seen consistently good adhesion with acrylics over oil paints or oil grounds. Although acrylics do seem to stick to dried oils in some cases, they can often be scratched or pealed from the surface. Even if there is apparent adhesion, we are not sure about long term stability of this combination. As mentioned in the article, watercolor might be a possible solution in this case. The surface should be slightly toothy so that the watercolor and subsequent oil paint layers have some grit to grab. We recommend testing. After the watercolors and oils have dried for several weeks, you can perform a down and dirty adhesion test as outlined in this article: https://www.justpaint.org/will-it-stick-simple-adhesion-testing-in-your-studio/

      We hope this helps! Best wishes in the studio.
      Greg

  5. Mark March 25, 2019 at 10:32 pm #

    Greg and Golden Staff,

    All the articles the Golden staff produces are so informative. Thank You!

    Mark

    • Greg Watson March 26, 2019 at 4:05 pm #

      Hi Mark,
      Thank you! Glad you like JustPaint. Most of the articles are written by our Technical Support team. We are here to help if you ever have any application or product related questions. help@goldenpaints.com or 800-959-6543.
      Take care,
      Greg

  6. Delofasht March 26, 2019 at 10:36 am #

    The article mentions oils degrading the fibers of the substrate should it be exposed directly, but I have spent a few years trying to locate any testing done in regards to this and have yet to find any. Is there a link to a test done that shows oil degradation of fabric or paper surfaces?
    I am looking for just oil on the surface, not oil paint or anything like that because pigments in paint have been shown to cause degradation to surfaces when exposed to oxygen, temperature, and other natural environmental situations.

  7. Clarence March 28, 2019 at 5:57 am #

    Good day/evening Mr. Greg.

    I am also wondering if Golden has any current and/or future plans to make water-soluble version of your Williamsburg oil paint range and/or mediums to make them water-soluble (i.e. water-miscible safflower oil) in order to achieve watercolor-like effects and make clean-up easier.

    Thanks.

    • Greg Watson March 28, 2019 at 11:55 am #

      Hello Clarence,

      Thanks for the comment. We do not currently have any plans to make water-miscible oil paints or mediums that could modify our current line. For a short description about how to clean your brushes when using regular oil paints without the use of solvents, see this blog post from our Williamsburg site: http://www.williamsburgoils.com/blog/?p=103

      Best wishes,
      Greg

  8. Alex March 29, 2019 at 3:09 am #

    Thanks Greg! I’m hoping you will undertake a study on the use of conventional oils over alkyd underpainting?

    • Greg Watson April 5, 2019 at 12:43 pm #

      Hello Alex,
      Thanks for the good suggestion! It seems like this combination follows the slower drying over faster drying model, which is recommended. We would not expect to see issues with this unless the alkyd layers were exceedingly glossy, which could cause adhesion issues. If this is a technique you use, you may be able to perform a simple adhesion tests to assure the conventional oils are adhering well to the alkyds. We outline the procedure for a simple adhesion test in this article: https://www.justpaint.org/will-it-stick-simple-adhesion-testing-in-your-studio/
      We recommend trying this on a sample or test piece. Please let us know if you see anything unexpected!
      Thanks again,
      Greg

  9. Irlynda Smith April 14, 2019 at 9:48 pm #

    I have been painting this way for almost 20 years. I’ve told a few people who thought less of me for the mere suggestion of using watercolor, acrylic and oils in the same painting.

    Thank you for clarifying this method as not only possible but historically accurate.

    • Greg Watson April 17, 2019 at 8:35 am #

      Hi Irlynda,
      You are welcome! It is great to hear you have had success with these combinations. Best wishes moving forward!
      Greg

  10. Jane O'Brien May 30, 2019 at 5:47 pm #

    Thank you ♥️ for sharing this with us. I’m doing Irish scenes for a shop and this is really making progress easier.

    • Greg Watson June 7, 2019 at 11:01 am #

      Hi Jane,

      You are very welcome! We are glad it has been helpful. Let us know how it turns out! It would be great to see some images if you feel like sharing!

      Thanks and best wishes,
      Greg Watson
      gwatson@goldenpaints.com

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