One of the worst things that can happen to an acrylic pour artist is to pour an amazing painting only to find some blemish or imperfection after it settles for a few minutes. One of the more common issues I have heard about from new artists is spots of canvas showing through the paint.
Bare canvas spots showing through your acrylic pour are caused by the fluid paint being pushed away from the canvas by oils like silicone, dimethicone, or even natural oils from your skin.
While an acrylic pour with canvas showing through isn’t the end of the world, I have found there are a few things you can do to limit how often this happens with your paint pouring art.
Why do Oils in Acrylic Pours Cause Bare Spots?
Oil additives are used in acrylic pours to help cells form. These cells are created when the lighter and less dense oils rise through the layers of paints and pull some of the colors with them creating multicolor blobs on the surface of the painting.
The problems start to happen on the outside of a pour where the paints are getting thinner as you have tilted off more paint. The oils gather on top of the puddles of paint. When you are tilting the paint flows over each other as you see in the picture below.
Ultimately the oil on top falls off the side of the puddle and meets the canvas before the paint does. The paint on top is then thinned as the paint is tilted off the canvas.
The oil that has touched the canvas sticks to the canvas and as the paint on top of it gets thinner it repels the paint away from the drop of oil. This causes there to be no paint on top of the oil and because the oil is transparent you see all the way down to the bare canvas.
These spots tend to happen more often on the outside edges of a pour because that is where the oil is most likely to tilt of the top of the paint puddle and because that is where the paint on top is going to be thinnest.
Easy Ways to Prevent Bare Canvas Spots on an Acrylic Pour
The simplest way to prevent bare canvas posts on your acrylic pour is to remove the ability for the additive oils to touch the bare canvas. If the oils never touch bare canvas first, they can’t repel the paint and create these spots.
Pre-paint Your Canvas so there is Always Color Underneath
The most straightforward way to prevent bare spots on your canvas is to pre-paint your canvas. This way if the oils do touch the canvas first it won’t be white bare canvas but already colored canvas that potentially shows through.
Normally I recommend you choose the base or main color of your painting to do this pre-painting with but if you want to add some pop on the outside edges of your painting you can also use your complementary color.
You can leave this painted layer wet or dry, but I have found that painting the color and letting it dry gives the most consistent results and prevents any of the white or gessoed canvas from showing through.
Use a Base Layer or Flow Extender to Prevent Bare Spots
If you don’t want to paint your canvas beforehand another easy trick is to use a base layer of wet paint or flow extender around the outside of your paint puddle.
This ensures you have paint all around your main puddle that has silicone or other oil additives in it. When you tilt your paint, you will be rolling over the base color or flow extender color instead of on to bare canvas.
I recommend that if you use either of these methods, you allocate between 30% and 60% of your total paint as your base paint or flow extender. The more of this paint you use the less you are going to distort the main design of your painting.
This happens because the main puddle of paint does not roll over itself and hide the outside edges of your puddle as it is slipping across the base paint or flow extender instead.
Thicker Paints do not get Repelled as Much by Oils
Another thing to note is thicker acrylic pour paint does not get pushed as easily as thinner pour paint. That means you are less likely to get bare spots along the outside few inches of your painting as you would with thinner paint.
The sides and corners are always going to potentially be a problem even with thicker paints because gravity is always pulling your paint downward and thicker paint just won’t have enough bonding strength with the side to stay thick.
Oils from Your Hands Can Cause Paint not to Stick to a Canvas
The last thing isn’t as obvious as the others because most people don’t realize how much oil your skin naturally produces.
These oils, while essential for good skin hygiene, can also cause the same problem with paint not sticking to your canvas, albeit usually at a much smaller scale.
The easiest solution is to wash and dry your hands before handling a bare canvas or using latex or other sterile gloves.
Keep Stored Canvases Dirt and Dust Free
The last thing to consider when getting bare spots on your acrylic pour canvas is to eliminate the potential for dirt and other contaminants from coming in contact with your painting surface.
I try to keep my canvas stored in an elevated place, so they don’t gather dirt and grime from the floor or me walking past them.
Put them in a place where you aren’t handing them often, so they remain and clean as possible.
Also, don’t remove the protective plastic packaging to ensure they remain clean and dirt-free for as long as possible.
Michael’s craft store bundles of canvases come with every other canvas being fully wrapped in plastic. I try to make sure a wrapped canvas is always on the top of the pile so any dust that drops lands on this protective barrier first.
A simple sheet or other easily removable covering can also act as the first line of defense for dust and air pollutants.
Gesso Canvases that are Dirty or Being Reused
If you can’t ensure your canvases remain clean one option is to always gesso before pouring so you know you have a clean base layer to start from. Gesso is more forgiving of dirt and oils than acrylic paint is and will help you to get uniform coverage on your acrylic pour.
When reusing a canvas that already has a shiny layer of paint or that has been varnished, a coat of gesso will help the second layer of paint adhere more readily to the surface.
When reusing a canvas, I always recommend cleaning the canvas with slightly soapy water to remove all dust and oils that might have accumulated.
Having trouble getting cells with silicone? This post on Acrylic Pour Cells gives you all the info you need to get amazing multi-color cells with your acrylic pour.
Canvas Showing Through an Acrylic Pour is Not Bad
Keep in mind that acrylic pouring is the creation of unique and personal artwork. Sometimes as artists, we think that everything should be perfect.
Mass-manufactured art is perfect. In my opinion, handmade acrylic pour painting pieces are unique because of their imperfections.
Don’t be too hard on yourself that you are seeing bare canvas spots on your art. It happens to us all and some of those spots I have left because they add to the unique quality of the painting.