When water is applied to paper, the fibers can soak up liquid and expand. This may create the infamous buckles and cockles that can be the bane (or joy) of those who paint with watermedia. This article reports on what happened when High Flow Acrylics and Heavy Body Acrylics were applied to Arches 140 lb. / 300 g.s.m. Cold Pressed Watercolor Paper, Arches 300 lb. / 640 g.s.m. Cold Pressed Watercolor Paper, Strathmore linen finish 400 Series 246 lb. / 400 g.s.m. Acrylic Paper, and a lighter weight Strathmore 300 Series 115 lb. / 187 g.s.m. canvas texture Canvas Paper. These paper choices allowed us to include two weights of professional grade cotton watercolor paper, an intermediate grade buffered wood pulp acrylic paper, and a student grade canvas paper. We found that the two heaviest papers, the 300 lb. cotton watercolor paper and the 246 lb. buffered acrylic paper, tended to dry with greater flatness. Depending upon the needs of the artwork, one of these papers might provide a solution.
We employed two paint applications. The first used undiluted High Flow or Heavy Body paint and covered more of the paper surface. In our tests, this approach caused the least buckling in the 300 lb. watercolor paper and acrylic paper, both of which remained mostly flat. The 140 lb. watercolor paper showed moderate reaction with low undulations of the surface. The second application process left more of the paper surface uncovered and used either undiluted High Flow or water-diluted Heavy Body. Again, the 300 lb. watercolor paper and acrylic papers showed the least buckling after drying. The acrylic paper tended to curl during painting and dried mostly flat. The diluted Heavy Body paint caused the 140 lb. watercolor paper to buckle more during drying, and the canvas paper to buckle the most during both application and drying.
Fiber content of the paper and sizing help determine the absorbency of the surface. These aspects may affect how a paper will react to water, both initially and in lingering planar distortions after drying. The weight is also important, as the lighter canvas paper curled up the most and the heavier weight papers retained the least buckles. How much water is used, how even the application, and how much of the surface is painted can also be important aspects in the extent and type of buckling.
We found two types of surface distortions were created with the application of water-borne acrylics to the papers: surface undulations in areas with more product or water, and the development of an overall curl to the piece of paper. In general, the watercolor paper was more absorbent, reacted more slowly to the water content of the acrylic paints during applications, and buckled less during painting. Although the 300 lb. paper reacted very little while painting or drying, the lighter weight version tended to develop area buckles during drying. The acrylic paper sometimes reacted by curling during paint application, however it tended to flatten out while drying and was not as prone to localized buckling.
It is always good to test a new paper to see how it will react with your painting techniques and materials. Remember that acrylics are water-borne paints, and even undiluted applications might cause buckling on some papers.
Heavier Paint Applications, Heavy Body
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Heavier Paint Applications, High Flow
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Lighter Paint Applications, Heavy Body diluted with less than fifty percent water
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Lighter applications, High Flow
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Thank you for the examples of different paints and different weight papers.
I paint with acrylics on watercolor paper, usually Canson 140lb/300gsm. I apply 3 coats of gesso to the textured side of the paper. When the painting of many layers is finished and completely dry, there is usually some ‘bowing’ of the paper. I apply three thin coats of water to the back of the painting, place it pigment side down on clean glass, wax paper over it, then a piece of wood on the waxed paper, completely covering the artwork, with weights of some kind on top of the wood – often books, which are handy. When the paper is completely dry, it is flat and stable. the texture of the painting does not seem to be compressed.
I have experimented with applying water to the back after gesso and before painting. results are variable, depending on how much paint is applied. sometimes i need to repeat the water layer on the back, sometimes not.
Hello Priscilla,
We are glad you found this testing of interest. Thank you for describing the process for flattening your acrylic paintings, we are sure other artists will find it helpful. A similar method is used to flatten watercolor paintings, although then the back of the paper is only slightly dampened since water is of greater concern.
Although your process is working beautifully, we wish to clarify for other artists that there is a possibility of change to the painting when flattening a paper substrate. Using weighted pressure to push a painted acrylic against another surface might create alterations to the painting’s sheen or texture. Weighted pressure may also transfer texture to the painting’s surface, or adhere the painting to the surface against which it is pressed. A sheet of thick unmarred glass would be a good surface to use as a base, since acrylic will not permanently adhere to glass.
Gesso is porous, so water may be filtering through it to the paper and causing buckling during painting. There is a chance that using undiluted Heavy Body and Gels over the entire surface might result in less buckling, while diluting with water and applying more paint in some areas of the paper and less in others would encourage buckling.
Happy painting,
Cathy
I gesso as well. I use Golden acrylics to paint on 300 lb. (640gsm) 30×22 inch watercolor paper — Fabriano and Kilimanjaro to name two. To avoid buckling, I gesso front AND back. Then I tape the paper to a work surface board leaving a carefully measured one-inch border. I gesso the front one more time to seal the masking tape edge. Then I paint. Afterward, I remove the tape and spray varnish the front and back— further protection against fingerprints and dirt. Yes, sometimes removing the tape lifts a small, thin, irregular layer of paper, or there are small paint bleed spots. Both issues are easily remedied with gesso touch ups. I’ve found this process to be very reliable — the end painting on paper is heavy (not really rollable). Customers like the substantial weight this process brings to a work on paper. You can see them at https://www.cynthiacoldrenfineart.com/works-on-paper
Hello Cynthia,
Thank you for sharing your process. We expect that other artists will find your information and experience helpful.
Cathy
Would a thin layer of Absorbent Ground Medium applied to the 140# paper help? I have never tried this product but would be interested in it for this and for applying over previously painted canvases.
Hello Lisa,
Thank you for your question. Applying a layer of Absorbent Ground over paper is likely to increase the absorbency and allow the paper to stay damp for a longer time. Depending upon the paper being used, the ground might encourage more buckling. Absorbent Ground will adhere to any surface to which acrylic paint will adhere, which encourages exploration beyond the possibilities offered by paper. The Absorbent Ground Tech Sheet offers more information which you might find of interest.
Happy painting,
Cathy
This is fantastic information, thank you!! I paint with my heavy body acrylics on watercolor paper when I travel – it’s only 150# but because it’s on a block, it doesn’t buckle at all. It’s a convenient way to paint plein air. Once I’m back in the studio, I can mount any successful pieces onto a cradled board.
Hello Angela,
Thank you! We are glad you found the testing helpful, and it is great that the surface is drying without buckles when you paint with acrylics on a watercolor block. We did not think to test that approach, so thank you for sharing! And yes, adhering paper to a board is one of the best ways to keep the paper (and painting) flat.
Happy painting,
Cathy
It’s good to see an organized comparison. The lingering question from most water media artists is; what/which of the many quality Golden mediums, gels, varnishes, or glazes can be used as an undercoat to a quality watercolor paper to both (1) prevent the water absorption buckling and (2) retain a “painterly”
surface. The 300 lb paper would always be 1st choice if it wasn’t 3x more expensive than 140 lb.
Buying stretched canvases on sale builds up a storage issue and using paper allows one to keep a lot of paintings for reference and gifts. So, there are a lot of peripheral benefits to developing some good techniques in this area
Hello Alan,
Since acrylic films are porous, water can filter through a layer of dry acrylic and into a paper substrate and create buckling. Although we have seen buckling when painting on papers coated with a medium or gel, exploring the differences would be interesting for a future article. Thank you for the idea! In the meantime, photographs of papers coated with Golden mediums can be found in Greg Watson’s article “Painting with Oils on Paper.”
Happy painting,
Cathy
Thank you for the information. So glad to have a dependable source when it comes to technique and supplies.
Rebecca
Hello Rebecca,
Thank you! We are glad you find our research helpful. If you have any questions as your paintings progress, please feel free to contact us in the Materials and Applications Department by calling 800-959-6543 or 607-847-6154 or by emailing [email protected].
Happy painting,
Cathy
Can you clarify what exactly is acrylic paper? Can you provide some brand names? Thanks!
Hello Judith,
Thank you for your question. Acrylic and oil papers have been formulated as substrates for painting media in an attempt to provide artists with alternative surfaces. Often these papers are intended for sketches and studies rather than for major works of art. When testing for this article, we used an intermediate grade Strathmore 400 series acrylic paper. This was slightly heavier than 140 lb. watercolor paper. The “Painting with Oils on Paper” article does contain Arches® Oil Paper, which also might be used with acrylic paints. We did not test other acrylic papers or boards, although we will provide links to a few options. Strathmore has a number of products intended for wet media in their 500 series artist’s grade category.
Hahnemühle offers oil and acrylic papers and boards and Canson® Acrylic, or Multimedia Artboard might be possibilities to explore.
These options provide differences in terms of thickness, longevity, and paper or board content. It is also possible that a watermedia board or watercolor paper board might be less prone to warping.
We hope this is helpful,
Cathy
I have been using acrylics as watercolor and getting lots of buckling. What about using acrylic paper? I just ordered a pad of that to try and see if it would be less.
Hello Roberta,
We found that buckling potential appeared to be related to the thickness of the paper, how evenly over the surface paint is applied, how absorbent the surface is, and how much water is used with the paints. A lot of water in an application can really call forth the paper buckles! However, we did find that the acrylic paper we tested did fairly well. Taping down the corners or edges of the acrylic paper helped control the tendency to curl while being painted on, and the thicker the acrylic paper the better it might resist buckling. We did not test applications that used as much water as a watercolor technique would, however in the article images 1A, 1D, 2A, and 2E show acrylic on an acrylic paper. We would recommend testing to see how the new paper reacts to your technique.
Happy Painting,
Cathy
I have painted with Golden fluid acrylics on Strathmore 500 series Aquarius II 80 lb watercolor paper for many years with great results.
Yes, it buckles when wet but so do most watercolor papers, again depending on how much water is used. The paper dries flat and I never ‘stretch’ or tape it down as I do with other weights/brands of watercolor paper when painting with fluid acrylics. I have also used gesso and other mediums on this paper and love the results repeatedly.
Hello Susan,
Thank you, it is wonderful to hear another suggestion for a paper that dries flat when painted with acrylics. Strathmore’s 500 Series Aquarius II® Watercolor Paper contains both cotton and synthetic fibers, a combination that may help it resist buckling. The 500 Series is also their line of professional products. We will certainly add this paper to our testing in the future.
Happy Painting,
Cathy
Cathy-
In your response to Alan you noted that, “Since acrylic films are porous, water can filter through a layer of dry acrylic and into a paper substrate and create buckling.” Are the GAC 100 and or GAC 700 mediums suggested for sealing surfaces “less” porous than other Golden products? We are looking for a Golden product to use as a sealer to Birch Panels that will be coated with subsequent layers of other Golden grounds, mediums, paints, etc with the intention of lessening as much SID over time, and to reduce the amount of water that will enter the wood surface via the primer.
Hello Jules,
Our current recommendation for a GOLDEN product to reduce Support Induced Discoloration would be either Gloss Medium (Polymer Medium Gloss) or GAC 100. Several initial layers of one of these would be needed. We actually have an article, “OPEN Acrylics, Shellac, and SID,” which discusses our most recent testing in this area. The article focuses upon OPEN since the slow drying nature of this paint provokes the greatest Support Induced Discoloration. We hope this is helpful–
Cathy
Hello Cathy,
In order to reduce moisture transfer to a #250 – #300 CP Rough paper substrate, can I brush on a coating of acrylic medium as an initial layer before applying gesso and fluid acrylics?
Regards,
Peter
Hello Peter,
Thank you for your question. Yes, you may coat a sheet of watercolor paper with an acrylic medium or gel to reduce absorbency in comparison to uncoated paper. Dry acrylic films remain porous, so some buckling and curling may still occur. For photographs of papers coated with Golden mediums, see Greg Watson’s article “Painting with Oils on Paper.”
Happy painting,
Cathy
Thank you for the article. I paint with 60, 98, 140 and 246 pound paper and my experience with warping matches your results. One thing I’ve noticed with the lighter papers is that the colors seem to become lighter after several days. I’ve always attributed this to “sponging” of the pigment into the paper fabric which dilutes the color. The heavier papers, while you would assume they would absorb more, don’t absorb as much pigment. Do papers exhibit different absorption amounts depending on fiber?
Hello Brett,
We are not certain what is causing the difference in paint appearance you are seeing with thinner papers and thicker papers, however it may have something to do with sizing and absorbency. We have seen differences in watercolor washes, where the same paint mixture appears lighter on a more absorbent surface and more saturated on a less absorbent surface. Watercolor paper is often both internally and externally sized to strengthen the paper and to reduce absorbency. Internal sizing is mixed into the paper pulp, and external sizing is applied after the sheet is formed. A strong layer of sizing on the surface may help the paint resist sinking into the paper, and so can help create vibrant color. Softer sizing results in a more absorbent situation, allowing watery paint to sink into the paper which may create a more muted color. Fiber types can have differences in absorbency as well, so that also may be playing a part in what is happening. Should you be interested, the Just Paint article “Paint and Paper: Making a Watercolor” discusses watercolor paper and sizing in greater depth.
Happy painting,
Cathy
I just wanted to say thanks so much for making this article! It was very very helpful and I know I’ll be referencing it in the future!
Hello Jenelle,
Thank you. We are glad you found the article helpful!
Happy painting,
Cathy
Hi, I use textures in my acrylic paintings on watercolor paper. Can someone advice a way to flatten the buckled paintings with textures? I cannot lay them flat on a surface upside down because of the textures. Please help.
Hello Udaya,
There is not a process that guarantees excellent results. There are, however, several avenues that might be worth exploration.
Any of these approaches should be tested before being used with an artwork, to be sure they work as desired. Please give us a call if you have questions or wish to talk through any of these options (607-847-6154, 800-959-6543).
Warm Regards,
Cathy