Priming a canvas with gesso is necessary when painting with oils because the linseed oil in the paint will eventually cause the canvas to deteriorate. You may be wondering if the same problem exits with acrylics.
Do I need to gesso a canvas for acrylic Painting? No, it’s not necessary to gesso a canvas when painting with acrylics. You can paint directly on the unprimed canvas because there’s nothing in acrylic paint that will damage the fabric.
Even though gesso isn’t necessary when painting with acrylics, many artist’s still use gesso because it offers many other benefits. The advantages and disadvantages of painting on unprimed canvas are explained in detail below.
The Benefits of Painting on Unprimed Canvas
It Saves Time
This may be obvious, but if you don’t gesso the canvas you can skip a few steps and begin painting immediately. It takes time to apply 1-3 coats of gesso and wait for it to dry between each coat. You can use this time working out the composition and applying color.
The Color of the Canvas Is Attractive
The light beige color of unprimed canvas can be appealing to work on compared to the stark white of a gessoed canvas. Many artists leave some of the bare canvas showing through in the finished painting. The natural color of the canvas has a natural and pleasing appearance. It reminds me of off-white drawing paper.
The beige color of the canvas will show through the areas of transparent color and slightly alter it. Whether this is an advantage or disadvantage depends upon what you’re trying to accomplish.
You may want to wipe the canvas down with a wet sponge and let it dry before painting on it. See the section below about removing wrinkles in the canvas for more information.
Paintings on Unprimed Canvas Have a Unique Look
You can achieve a watercolor style by painting on raw canvas with thin acrylics. Acrylics typically have a glossy appearance. But when you paint with diluted acrylics on unprimed canvas it dries to a matte surface because it soaks into the canvas.
You can also wet the canvas and paint “wet into wet” which is a popular watercolor technique. Painting into wet paint with thin acrylic paint will help to create soft edges and other watercolor effects. The end result is a style that’s normally impossible to achieve with acrylics.
There are oil paintings that are on raw canvas but it’s not something that I recommend. The linseed oil will seep into the canvas and discolor it. Eventually the oil will break down the canvas. Acrylics have the advantage here, as there’s nothing in them that will harm the canvas.
Abstract Stain Paintings
Thin acrylic paint has been used by artists to create abstract “stain paintings” that have a watercolor feel. Many abstract artists in the 1960’s used this technique. Helen Frankenthaler was well known for her large abstract color field paintings. They’re similar to watercolor paintings where the colors flow and bleed into each other. Her early work was in oils but she eventually switched to acrylics.
It’s also possible to paint flat areas of color onto unprimed canvas. The Protractor Series by Frank Stella were painted in this manner. Other artists who painted with acrylics on unprimed canvas are Kenneth Noland, Morris Louis, and Ronnie Landfield.
Another way in which this technique is similar to watercolor painting is that it’s easy to overwork the painting and lose the spontaneous look. Once you apply too many layers of paint, the texture of the canvas begins to fill in. If you apply additional paint it doesn’t have the same matte finish because it sits on top of the canvas.
The Disadvantages of Painting on Unprimed Canvas
Raw Canvas Often Has Wrinkles and Folds in It
One of the reasons artists apply a coat of gesso to a canvas is because the moisture in it will cause it shrink and tighten on the stretcher bars. This is similar to how washing a pair of jeans makes them tighter. As the canvas begins to tighten, it smooths out any small wrinkles in the canvas.
If there are wrinkles in this raw canvas and you begin painting on it, they may show up in the brushstrokes. One way to avoid this is to wash the canvas with a wet sponge after you stretch it on the stretcher bars. Once it dries it should tighten and smooth out.
If the tension in the canvas needs adjusting you should make those changes before painting on it. You can remove some of the staples and make adjustments. This is much easier with raw canvas than with canvas that has a couple layers of gesso on it.
Raw Canvas Repels Water
Another reason why you might want to wipe the canvas down with a wet sponge is because it has a residue on it that repels water. Washing it with a sponge will help to remove it. This is important if you plan on painting with thin washes of acrylic. You don’t want the thin acrylic paint to bead up on the canvas as you’re painting. Thicker heavy body acrylics probably won’t have this problem.
It’s important to only wash the canvas after you stretch it and staple it to the stretcher bars. I don’t recommend washing the loose canvas in a washing machine. The washing machine will put deep wrinkles in the fabric that are very difficult to remove.
Acrylics Dry Faster on Unprimed Canvas
The first few layers of acrylic may dry faster if you paint directly on raw canvas. The cotton fabric is absorbent and it pulls the moisture out of the paint, making it dry faster. Once you have a layer or two of paint on the canvas the following layers will dry at the normal rate.
The faster drying times will make it more difficult to blend the colors, especially if you work with thin layers. Thin layers tend to dry faster than thick layers. It will be more difficult to spread the paint around too.
Acrylic paint that has been diluted with a lot of water will stay wet longer. Typically, you don’t want to over dilute acrylic paint because you’re also diluting the binder. But if the first layer of color is thin enough to absorb into the canvas, then it may not be a problem.The pigment will settle in the fibers of the canvas. You should conduct an adhesion test before using this technique on an important painting.
Raw Canvas Is More Susceptible to Damage
If some of the areas of the finished painting are left as bare canvas, they’re more susceptible to damage. Dust often accumulates on the surface of paintings. The rough and absorbent canvas makes it more difficult to clean. The same is true for smudges or other marks.
A canvas that has multiple layers of acrylic paint has a smoother slick that’s easier to clean.
Applying a couple coats of gesso to the canvas also makes the fabric a bit sturdier. Compare a piece of primed canvas to raw canvas. A canvas that’s primed with 3 coats of gesso is more difficult to fold than unprimed canvas. It also doesn’t stretch as much when you pull on it.
The gesso will help to fill in some of the tiny pinholes that are found in the weave of the canvas. Some of the cheaper grades of canvas are somewhat see-through when you stretch them. You can see the faint outlines of the stretcher bars through the canvas. Applying a few coats of gesso should fill in the small holes in the weave of the canvas and eliminate the see-through effect.
If you decide to paint on unprimed canvas, try to find one that’s a little bit thicker and with a tighter weave than normal.
Drawing on Unprimed Canvas Is Difficult
A couple of coats of gesso fills in the roughest parts of the canvas while leaving a very matte surface that’s great for drawing.
Raw canvas has a lot of texture to it that seems to make the point of a pencil “catch” in the low spots of the canvas. This is especially true if you’re using a mechanical pencil with thin lead because it’s thin and prone to breaking. If you want to draw with graphite on unprimed canvas then you may want to use a graphite stick because it has a broader edge to draw with. Lead holders also have thicker lead than conventional mechanical pencils.
A softer pencil such as one with a hardness of 6B may work well, especially if the point is dull and rounded over. The round point won’t catch as much and the lines should be darker. However, softer leads such as 6B will smear more than a regular HB pencil.
Unprimed canvas provides a softer surface to draw on because you’re basically drawing on fabric. You will be able to tell the difference because it gives a little bit when you draw on it. The lines will be also be lighter.
Thick Layers of Acrylic Gel Can Turn Yellow as It Dries
Applying very thick layers of acrylic gel to unprimed canvas or wood may cause it turn Yellow as it dries. This is more likely to happen when painting on wood or masonite than on canvas. This is known as SID, or Substrate Induced Discoloration. What’s basically happening is moisture from the gel causes the impurities in the canvas to migrate into the gel and turn it Yellow or Brown in color.
Thick layers of gel take longer to dry so this allows more time for the impurities to migrate into the gel.
Golden has extensive information on Substrate Induced Discoloration if you’re interested in reading about it. According to Golden, they recommend applying multiple layers of gloss medium and gesso to create a barrier. Then you can apply thicker layers of gel over it.
Final Thoughts
Painting on raw canvas can create interesting effects that are normally impossible to achieve with acrylics. The natural color of the canvas can be incorporated into the painting.
There are a few differences in how the unprimed canvas alters the painting experience, but the information in this post should help you to avoid these surprises.
