Cracking & Crazing Problems with Acrylic Paint Pouring

WHAT IS CRACKING AND CRAZING?

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

What is the difference between cracking and crazing?

Here are the official definitions according to Google:

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 painting’s risk of not drying because the paint’s water molecules can’t evaporate. Low humidity areas run the risk of the paint drying too 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 the 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 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 acrylic paint drying process science, visit Just Paint: CLICK HERE.

Using Too Much Paint

The nature of acrylic paint pouring techniques is to use 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 painted first.  I do this because while I am working on a technique, if I happen to LOVE the design, 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 on the techniques, I also keep in mind that “less is more.” I can always add more paint to the edges or 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 online. 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 canvases or value canvas bundles. These are not bad to use, but they have 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 top and bottom measurement. Fit the board between the frame and the canvas. This creates a firm support for the canvas as you create your masterpiece and 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. Most canvases came with these wood keys in the past, 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 of mixing water with acrylic paint when it’s the complete opposite. Water does not work well with acrylic paint pouring because it changes the paint’s consistency by making it too thin. It also changes the pigment density, which makes the color more washed out, and it lessens the paint’s adhesion 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 makeup of acrylic paint by adding water and pouring mediums needs to be done with care 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!