Cracking & Crazing Problems with Acrylic Paint Pouring

crack /krak/

1. a line on the surface of something along which it has split without breaking into separate parts. “a hairline crack down the middle of the glass”

2. break or cause to break without a complete separation of the parts. “the ice all over the lake had cracked”

craze /krāz/

1. a crack in a surface or coating (as of glaze or enamel)

2. produce a network of fine cracks on (a surface). “the lake was frozen over but crazed with cracks” 3. to develop a mesh of fine cracks

In acrylic paint pouring, crazing is a term used to describe cracks or lines that appear once the painting has dried.

Crazing happens when the top layer of the painting dries faster than the layers underneath which are still wet. There are several reasons why the top layer will dry quicker than the bottom layers.

Unintentional cracking or crazing often happen during the painting process when the artist least expects it. Some are the result of applying a paint, gel or medium a bit too generously, and others happen because external factors such as temperature, humidity, and airflow are not taken into account. Even if an artist has used a product successfully for years, defects can occur. When troubleshooting, consider the impact of the immediate environment and changes in the weather. What worked perfectly in the summer may not work at all during the winter months.

Just Paint

Temperature, Weather, and Air Pressure…. oh my!

Believe it or not the temperature, weather, and air pressure do affect your painting. It is best to keep your workspace between 65-75 degrees Fahrenheit for the best results. Temperatures over 75 degrees Fahrenheit run the risk of the top layer of paint drying faster than the bottom layer (causing crazing) and temperatures under 65 degrees Fahrenheit run the risk of the painting not drying, slow drying or freezing.

Areas with high humidity run the risk of the painting not drying because the water molecules in the paint can’t evaporate. Low humidity areas run the risk of the paint drying to quickly and crazing because the water molecules in the paint evaporate at a much faster rate. It is best to do some research for your area and make some tests or experimental paintings to gauge how slow or how quickly your paint will dry.

Airflow and Elevation

Another factor to consider is the airflow in your work studio or room. If you have a fan blowing on your drying painting in a low humidity climate then chances are that the top layer will dry faster and cause crazing or cracking. If you have a fan blowing on your drying painting in a high humidity climate then chances are this will help your painting dry and not cause crazing.

Blowing on a surface causes the air around that surface to change.  In the case of the drying paint, the air right near the surface is accumulating more water and solvents from evaporation.  It takes time for these evaporated gases to move away from the painting as it equalizes over a larger area. 

As was mentioned above, the more humid the air is around the painting is the less quickly evaporation occurs.  When an external force moves the air around the painting, that humid air is quickly replaced by less humid air, allowing the evaporation process to move more rapidly. 

Left Brained Artist

High elevations will help your painting to dry quicker because of the higher air pressure. Air pressure helps molecules move faster. Lower elevation areas will slow the drying of your painting. For more information on the drying process, here is a great article I found by the Left Brained Artist: CLICK HERE. If you would like to dive deeper into the science of the acrylic paint drying process, visit Just Paint: CLICK HERE.

Using Too Much Paint

The nature of acrylic paint pouring techniques is to us too much paint. We want to make sure we mix more than enough paint to cover our canvas, we pour the paint, dip the paint, swipe the paint and tilt the paint off the canvas. During the process when we see a design we fall in love with we want to stop and call it “done”. Paying attention to how much paint is actually on the canvas is important. If you leave a thick layer of paint then the chances of your work crazing and cracking will be high.

When I work on my paintings, I usually make sure the edges and corners are covered with paint first. I do this because while I am working on a technique if I happen to LOVE the design in the process I can then stop without having to worry about using more paint to cover the edges and the corners.

I always mix more paint than needed because I know I can save my paint for another project. While working the techniques I also keep in mind “less is more”. I can always add more paint to the edges or to areas that don’t look good but it is hard to remove paint without compromising your design.

The Importance of a Quality Stretched Canvas

Pre-stretched canvas is readily available for purchase in craft stores, hobby stores, and on-line. They are convenient and quick to use but if the canvas is not stretched properly it can sag in the middle. You will see this in the beginner level canvas’s or value canvas bundles. These are not bad to use but they do have some limitations, such as not being stretched properly. Using a “saggy” canvas will cause your paint to pool in the middle in a thick puddle and as it drys it can craze or crack.

If you have a canvas that sags don’t throw it away! Here are a few quick fixes you can try:

• Measure the inside frame of the canvas. Cut chipboard or another firm material at least 1/2″ bigger than the measurement of the sides and 1″ smaller than the measurement of the top and bottom. Fit the board between the frame and the canvas. This creates a firm support for the canvas as you create your masterpiece and when you finish with resin. When you are done, remove the board.
• Take a spray bottle of water and spray the back of your canvas (don’t soak) and in between the frame and canvas. Let dry near a heated area or dry it with a hairdryer. This will “shrink” your canvas and create a tighter surface for you to work on.
• In the canvas frame, you will see holes or notches that look like rectangles in the corners. These are to insert wood “keys” into. In the past, most canvas came with these wood keys but now you need to purchase them separately. Taking a hammer, gently tap two keys into each corner. This will tighten your canvas by pushing the frame out. This does take some time to do and in today’s world, it can be easier to grab another canvas or try one of the methods above.

Using Water with Caution

Water breaks down the binder in acrylic, thinning the paint so that it looks like watercolor and allows it to sink into the surface, resulting in a matte finish. Acrylic medium minimizes the need for the addition of water and allows the paint to sit on top of the surface, maintaining a rich, glossy appearance. The amount of water you add depends on the desired effect and the surface. Adding up to 30 percent water to acrylic paint thins it but still allows it to coat a surface. Adding 60 percent or more water creates a watery paint application called a wash. Rubbing a wash into an absorbent surface so that only a hint of the color remains is called a stain.

Artists Network

When the term “paint mixing” is used, most people instantly think to mix water with the acrylic paint when its the complete opposite. Water does not work well with acrylic paint pouring because it changes the consistency of the paint by making it too thin. It also changes the pigment density which makes the color more washed out and it lessens the adhesion of the paint to the painting surface. Water should be used in moderation alongside a quality pouring medium and distilled water should be used, not tap water.

Changing the make-up of acrylic paint by adding water and pouring mediums needs to be done with care in order to achieve the desired results. Crazing and cracking is an unexpected result and can ruin your hard work. Taking the time to learn how to prevent crazing and cracking will help you enjoy this craft and create beautiful masterpieces!