Creating the Perfect Ultra-Smooth Canvas for Airbrush
by A.D. Cook
Published in Airbrush Action Magazine, December 2004 (updated April 2020)
Canvas and fine art go hand-in-hand. But readily available off-the-shelf canvas really isn’t made for airbrushing. Even stretched and “prepared” canvas that is marketed to airbrush artists has a lot of weave texture in it, which may be okay if that’s what you want. I prefer a much smoother surface – something a bit closer to hot-press illustration board. In consideration of that, I’ve developed a process that allows me to paint on canvas that is smooth and forgiving and yields an incredible surface to work on.
So the question I get asked often is “Why go to the effort to prepare a canvas when other surfaces are available?” In response to that I have a lot of reasons:
- A properly prepared canvas is the perfect surface for acrylics and airbrush mediums.
- The finished painting is relatively lightweight compared to creating the same work on a board or metal surface of the same size.
- I like the process of painting on canvas. It is a flexible medium that is forgiving and accepts a variety of mediums easily.
- Art on canvas appeals to people as “fine art”, whereas art created on illustration board or some other surfaces have the perception of being illustrations. Collectors of art see the value as greater when a painting is created on canvas.
- Canvas can be purchased or stretched to just about any size. I often work large, with paintings averaging 12 to 20 square feet, and sometimes larger – certainly larger than most available illustration boards.
- Canvas can be prepared for my satisfaction, allowing me to paint on the surface I want.
- Canvas is durable. Paintings produced on canvas have the proven potential to last hundreds of years.
- Canvas doesn’t have to be framed under glass like works created on illustration board
Having made my case for canvas, let’s get to work and create the perfect ultra-smooth canvas for airbrush. For starters, just about any off-the-shelf canvas will do, but my personal feeling is if you’re going to invest the time to create a work of art, start with good quality, pure cotton canvas. I prefer the gallery-wrap canvases since they can be displayed nicely without a frame by simply painting the edges. Gallery-wrapped canvases are the ones without any visible staples on the sides, so the sides are nice and smooth. If I’m creating a custom-sized canvas (something not available off the shelf) I staple my canvas to the stretcher bars from the back, essentially creating a gallery-wrap canvas myself. If you’re planning on framing the finished painting then the gallery wrap may not be as important, but one thing to keep in mind is that the gallery-wrap canvases tend to come stretched on thicker stretcher bars which are a benefit since we’re going to be putting the canvas through a bit of a workout.
Before we get too far let’s look at a quick list of tools and materials (in order of use):
- Stretched canvas
- Acrylic Gesso
- Squeegee – I prefer 3” x 5” ones like sign shops use to apply vinyl
- Small bucket
- Sandpaper – wet/dry sandpaper*
- Sanding Backing Pad*
- Clean Cotton Rag
- 3M Scotch-Brite™ Scuff Pad* – I use the gray ones which are equal to 400-600 grit sandpaper
- Dust Mask*
- Tack Cloth*
(*) Available at automotive paint supply shops or auto parts stores
Now to the fun part…
Step One — Applying Gesso
I buy gesso in the one-gallon tub for easy access. I can scoop gesso directly from the tub and apply it straight to the canvas. I prefer Golden brand Gesso Acrylique #3550-8, but you can use whatever works best for you (don’t skimp here – the price of good gesso and not-so-good gesso is negligible). Support your canvas on something vertical where you can easily access it. I use a good sturdy easel for this, but you could just as easily lean it against a wall. Apply gesso to the canvas with the squeegee. When applying the gesso don’t scoop too much out at a time – just enough to apply easily. Using long strokes I spread the gesso onto the canvas and actually push the gesso into the canvas’ surface. This is important… The goal here is to level out the rough surface and get the gesso to become part of the canvas, not just sit on the surface. Equally important is the process of applying very thin layers. It’ll take a few layers (or coats) to eliminate the canvas’ texture. Depending on how light or heavy you apply the gesso it could take anywhere from five to ten coats. Apply your first coat as even as you can, but don’t worry if you miss a spot here and there. Let each coat dry thoroughly before applying additional coats of gesso. I rotate my canvas between coats to help create a more consistent surface. This also helps me see any areas that I may have missed in previous coats. Try, as much as possible, to avoid creating ridges when you apply the gesso. Some will naturally happen, but attempt to avoid it as much as you can. Don’t worry too much about what does get built up – we’ll address this later. Continue to add layers of gesso until there is no more visible canvas texture, but keep the coats light. It’s better to have ten thin coats than two heavy ones. This process is usually spread out over a few days to allow drying time between coats, so I like to prep multiple canvases at the same time. As a note, if the canvas is cold to the touch, it’ll need more drying time before applying the next coat.
Step Two — Wet Sanding
Once the canvas has multiple coats of gesso on it, it may lack canvas texture, but you’ll have added other types of texture from the squeegee process – mainly streaks of gesso build-up and other imperfections. The next step is to wet-sand the canvas to eliminate any texture you’ve added to the canvas. Make sure that the canvas has cured (dried) for a day or two before wet sanding. Wet sanding is a process usually practiced within the automotive industry. It involves using a particular type of sandpaper and water to achieve a smoother surface than regular sandpaper could ever create. I use 320 grit wet sandpaper when sanding gesso. First off, fill your bucket with warm water and allow the sandpaper to soak for 15 minutes. This helps to soften the sandpaper and prepares it for use. This would be a good time to soak a clean cotton rag with warm water and ring it out so that it’s damp – almost dry, but still a little moist. Wrap the sandpaper around your sanding backing pad (sanding block) and begin lightly wet-sanding the canvas focusing on the areas with the rises and imperfections. It helps to keep the canvas vertical while sanding. Be sure to keep the sandpaper wet throughout the sanding process and use your damp cloth to wipe off any mess as you move along. Be especially careful to not get too aggressive in the sanding process. You’ll want to avoid sanding past the gesso and into the canvas material which would cause damage and compromise the canvas material itself. If that happens you might have to start over with a new canvas (patience is essential here). Rotate the canvas often as you sand and continue to sand until the canvas is glass-smooth everywhere. I find it helpful to look across the canvas rather than at the canvas to find any imperfections. I do this by moving my eyes to the edge of the canvas and looking across it with light-reflecting at its surface. Automotive guys will be familiar with this process. You can also run your hand along the canvas’ surface to feel for any imperfections. Essentially, the goal here is to create a surface that is as smooth as a piece of glass. When you’ve completed the sanding process wipe the canvas down with a clean damp rag and let it dry completely. The next day I look over my canvas and do some additional wet sanding if necessary. This is my chance to fix any last concerns I might have regarding the near-finished surface. If I find that I can see canvas texture I can still add more gesso at this point (step one), let it dry, and do some more sanding tomorrow. I can continue this process until I’m completely satisfied with the canvas’ surface. If it looks good I can go to the next step.
Step Three — Scuffing the Surface
If you’ve followed these steps properly you’re probably thinking… “I have a beautiful smooth canvas, but paint’s not going to stick to this”. You’d be right – not most water-based airbrush mediums anyway, or at least not very reliably. This next step will help with that. Take your Scotch-Brite™ Scuff Pad and lightly scuff the entire surface just enough to provide an even tooth, but be thorough. For your own health be sure to wear a dust mask whenever you sand gesso (or anything else for that matter) and work in a well-ventilated area. Gesso contains a high concentration of Titanium Dioxide, which is great for covering canvas but it’s not a very healthy thing to breathe. The objective here is to have a relatively texture-free surface, yet with just enough tooth for paint to adhere to. Use a tack cloth at this stage to remove any dust created by the scuffing process.
Step Four – Priming the Canvas
Now you’ve got a nice canvas to work on, but it’s not quite there. The last step is to prime the canvas with airbrush paint. I prefer to prime with the lightest color I plan to use in the painting itself, applying the paint with an Iwata RG-2 spray gun with a fan nozzle, or for larger canvases, I use an Iwata LPH-400 spray gun. If I intend to use white in my painting, I use straight white to prime so that when I apply more white (or derivatives thereof) in my painting it’ll match the background and not look out of place. You can prime it in any color you wish, but by all means, prime it. This is an important step in creating an evenly finished surface. I recommend spraying multiple light coats of paint rather than one or two heavy coats. Each coat should be applied in a different direction to provide an even finish with no visible strokes or patterns in the completed surface. To accomplish this, simply spray the first coat in horizontal passes, the next in vertical passes, then diagonal, and so on. Allow the surface to thoroughly dry before drawing or painting on your ultra-smooth canvas (allow 24 hours before working on it). When you look at the finished canvas it’ll have the look and feel of a large sheet of illustration board. Mine looks like a fine hot-press board. It’s literally that smooth. You can’t see a speck of canvas texture in it, and looking at the front of the canvas I think most people would be hard-pressed to believe that it’s even a canvas. I like the way paint takes to its surface. Although it’s kind of an involved process, it’s definitely worth the effort if you like the feeling of a painting on canvas without the look of the canvas’ texture.
Cautions and Considerations
There are a few things to keep in mind as you work through the process of creating your perfect ultra-smooth canvas for airbrush.
- Gesso is not putty or body filler. To prepare a canvas correctly you must apply thin light coats. Multiple thin coats are better than a few heavy ones. Don’t be surprised if it takes six or more coats to eliminate the canvas’s tooth.
- Patience is key. Each coat of gesso must have ample drying time.
- Any texture left in the gesso process will telegraph in the finished art, which is fine if that’s what you want, but if you’re looking to create an ultra-smooth surface you’ll want to look over your canvas carefully before beginning your painting, and make adjustments if necessary.
It may seem like it takes a long time to prep a canvas with this process, but it’s really not that involved once you start. The overall accumulated time in any given canvas is really just a few short hours, even for a large canvas. The fun part here is to experiment. The process I’ve outlined is one that works for me and yields a surface that I like to work on. You may want to try different squeegees or even different sanding processes to see what works for you. If you want to prepare a canvas with a finish more resembling a sheet of cold press illustration board you can adjust it in the priming process by putting down more paint as a primer, stippling it to give it a slight texture, or adjusting your air pressure to manipulate the spray. You can even vary the texture if you like – smooth in some areas – rough in others. The potential surface possibilities are endless. In the end, you’ll have created a surface that is beautiful unto itself, requiring only your art to enhance the canvas further. By the way, I personally find watercolor pencils ideal for the drawing stage on the finished surface. The finished surface as prepared above is an excellent surface to just draw on as well, accepting both pencils and paint quite nicely. But again, experiment — just have fun with it.