Why Is My Acrylic Paint Cracking

If you’re a painter, you know how frustrating it can be when your beautifully-painted canvas starts cracking in front of your eyes.

As an artist, the integrity of my work is one of the most important things and this unexpected occurrence can be downright disheartening.

So why does it happen in acrylic pour paintings? In my experience, cracking in acrylics happens as a result of improper technique or aging, but most often due to the paint being applied too thickly.

Therefore, to avoid disaster with your next project, read on to understand what causes acrylic paint to crack and learn how careful application along with certain preventative measures can help deliver successful results every time.

Understanding The Difference: Cracking Vs Crazing

Cracking is a more severe type of imperfection that occurs when the top layer of the paint dries faster than the layers underneath, causing stress and tension that result in visible fractures or breaks in the surface.

Crazing, on the other hand, is a more subtle type of imperfection that creates a pattern of small cracks or fissures in the surface of acrylic pours. It occurs due to the shrinking and contracting of the paint film during the drying process.

Crazing is often less noticeable than cracking and does not penetrate as deeply into the surface as cracks do.

Other Types of Acrylic Paint Cracks

There are common forms of cracking that can occur in acrylic paint, including the following:

Hairline Cracks

Hairline cracks are small, linear cracks in the paint surface that can be caused by many factors including old age, improper painting techniques, or environmental conditions.

They are typically thin and widely spaced which gives them their name. Hairline cracks can be repaired with a spackling compound or primer to fill in the gaps and allow for a smooth, even finish.

Crazing

Crazing is a type of cracking in acrylic paint that occurs when a thin, web-like pattern of cracks form during the painting process.

This type of crack is usually caused by a combination of moisture, exposure to extreme temperatures or age.

Crazing can be repaired using a thin layer of paint along with sandpaper and primer to fill in the cracks. 

Alligatoring

Alligatoring is a type of cracking that results in large, jagged shapes resembling the skin of an alligator.

This type of cracking is usually caused by improper painting techniques, over-thinning the paint, or from aging and weathering.

Alligatoring can be repaired by sanding down the affected area and applying multiple coats of primer and paint. 

Flaking

Flaking is a type of cracking where the paint surface begins to break away in large chunks.

This can be caused by improper painting techniques, using the wrong type of paint for the surface, or old age.

To repair flaking, it is best to sand down the affected area and apply new primer and paint. 

Peeling

Peeling is a type of cracking where the paint lifts up or away from the surface in layer-like strips or sheets.

This can be caused by improper painting techniques, using the wrong type of paint for the surface, or environmental factors such as moisture.

To repair peeling, it is best to sand down the affected area and apply new primer and paint. 

Why Is My Acrylic Paint Cracking

Acrylic paint can crack due to several reasons, including applying thick layers of paint, using a low-quality or inappropriate paint, mixing the paint with too much water, painting in a dry environment, or not letting the layers dry completely before applying the next layer.

Reasons Why Your Acrylic Paints Crack

Several reasons may cause your acrylic paints to crack after drying. Some of the most common include: 

i. Low Quality Paint

Acrylic paints are not all created equal, and cheap paints may contain low-grade pigments and inadequate binders that make the paint less flexible and prone to cracking.

Inferior brands of acrylics may also contain improper ratios of pigment to binder, resulting in a product that is too brittle and prone to cracking when dry. 

ii. Too Much Paint or Too Thick Layers

Overloading your canvas with too much paint or painting thick layers can cause the paint to crack as it dries, especially if the lower layer has not been given enough time to properly dry before applying another layer.

If you want to apply multiple layers of paint, make sure each layer is thin and give it enough time to dry (or even use a hair dryer!) between layers.

iii. The Paint is too Thin

If the paint has been too watered down or over-thinned with mediums, it can become fragile and prone to cracking as it dries.

To avoid this, make sure to use a thicker consistency of paint and adjust the viscosity as needed with mediums rather than water. Here is how to make acrylic paint thicker without cornstarch.

iv. Bad Canvas

If you are painting on an improperly prepared canvas, it can lead to cracking in your painting as the canvas may not be flexible enough to hold the wet paint.

To protect your canvas acrylic painting from such issues, it is important to use a good quality canvas primed with gesso.

v. Environmental Factors

Humidity, temperature, and other atmospheric conditions can affect how paint dries, which can make your acrylics more likely to crack.

Try to work in well-ventilated areas away from direct sunlight and drafts to maintain a consistent environment.

vi. Poorly Prepared Painting Surface

If the surface you are painting on is not properly prepared, it can lead to cracking in your paint as it dries. 

Make sure any surfaces you use are free from dirt, dust, and grease before applying any paint or mediums.

Additionally, an insufficiently sealed surface may absorb the binder in your paint, causing it to crack.

vii. Incompatible Acrylic Mediums

Incorrectly using mediums that are not formulated for acrylic paints can lead to cracking and other problems as the painting dries.

Make sure to read the instructions on any mediums you use and only mix compatible products together to ensure your painting will not crack. 

Effects Of Cracked Paint

Cracked paint on a wall or other surface can be both unsightly and potentially hazardous. Some of the potential effects of cracked paint include:

Aesthetic issues

Cracked paint can result in an unsightly and uneven surface. As the underlying layers of paint fail to adhere, it becomes more difficult to repair. 

A patchy appearance that is marred by lines of separation between the various coats of paint may be present and detract from the overall look of a structure or object. 

Vulnerability to Further Damage

Cracked paint is often more susceptible to further damage as it lacks adhesion and durability.

This includes peeling or flaking off on its own due to environmental factors such as temperature and humidity, or from the pressure of nearby objects or activity.

In addition, cracks can lead to further separation and expansion of the existing damage, leading to even more unsightly results.

Issues With Adhesion and Durability

Cracked paint is not as strong as properly applied paint and therefore cannot stand up to normal wear and tear.

This means that it is more prone to fading, chipping off, and peeling than paint that has been applied according to the manufacturer’s instructions.

It may not be as effective in protecting materials from water or other liquids, making them vulnerable to further deterioration.

As such, cracked paint requires repair or replacement for optimal results.

Safety Hazard

Cracked paint can cause a safety hazard in that it may contain lead, asbestos or other hazardous materials.

If exposed to the air, these particles can become airborne and cause respiratory problems, skin irritation, and other health concerns. 

Allergies

Cracked paint can cause allergic reactions due to its dust particles, as well as any allergens that may have been present in the original material.

This is especially true of older homes where lead-based paints were common, although newer paints may still contain a range of toxins that could trigger allergies or other health concerns. 

Risk of Fire

Cracked paint can create pockets where air and heat may become trapped, leading to an increased risk of fire.

This is especially true in areas such as attics or basements where the buildup of particles can lead to a higher chance of flame ignition if exposed to sparks or other hot surfaces.

Debris

Cracked paint can lead to the shedding of small particles that may accumulate in nearby areas, creating debris and a mess.

This can also be dangerous if swallowed or breathed in, leading to further health issues. Read to find out more on what happens if you eat acrylic paint.

Additionally, this type of accumulation can attract pests such as mice and other animals, potentially causing further damage to property.

Read Also: How to Drill Holes in Plexiglass Without Cracking

How to fix cracked acrylic painting

I have tried and tested numerous techniques for repairing cracked acrylic paintings, from simple solutions to more ones. Some of the most common methods are:

Prep Your Surface

Before beginning any repairs, it is important to prepare your surface. Use a rag to remove any residual paint and smooth the surface. Wipe away any dust or debris before beginning to acquire perfect work. 

Use Fine Grit Sandpaper

After preparing the surface, use fine-grit sandpaper to lightly smooth the area where you plan to repair. This will help to ensure that the repair material is applied smoothly and evenly.

Scrap and Re-Pour

This method requires you to scrape away any loose material from the painting and then pour fresh acrylic paint onto the surface and build it up until you have a smooth, consistent finish. Make sure to use thin layers of paint and brush in one direction, preferably from the center of the painting outwards. When you have finished building up your layers, let it dry for at least 24 hours before sealing or varnishing.

Fill with Paint

This method is a quick fix for cracked areas and involves filling the cracks with fresh acrylic paint. Apply the paint with a small brush or palette knife and use thin layers until the crack is completely filled. 

If necessary, you can add additional layers of paint to give the repair a more finished look. When you have filled the cracks, let it dry for at least 24 hours before sealing or varnishing.

Seal or Prime Your Surface First

After applying any repairs to the painting, seal the acrylic on plastic or vinyl wave. This will help to protect the painting and ensure that the repairs don’t cause any further damage. To seal or prime your surface, use a thin layer of acrylic gesso. This will help to create a smooth surface and protect the painting.

Let the Paint Dry

After applying a thin paint layer, let it dry for at least 24 hours before continuing with any repairs. If you apply any additional coats of paint, let each coat dry thoroughly before proceeding.

Add a Layer of Varnish

After the paint has dried, add a thin layer of varnish to the painting. This will help to protect the painting and ensure that future repairs are easier. The three brands of acrylic polymer varnish that I would recommend are Golden Polymer Varnish, Liquitex Acrylic Polymer Varnish, and Lascaux UV Varnish.

How To Fill Paint Cracks On Acrylics Paints

Can I use acrylic paint on walls? Find out before you continue with the step by step process below.

Materials

• Prepare the surface
• Choose the color
• Fill in the cracks
• Cleaning
• Dry and repeat

Procedure

Step 1. Prepare the Surface

Before you start filling in any cracks on acrylic paints, you need to make sure that the surface is clean and free of dirt and debris. Use a damp cloth to remove any dust or other particles from the wall. Make sure that there are no traces of oils or grease left behind as this can interfere with how the paint will adhere to the surface.

Step 2. Choose the Color

Once you’ve prepared the surface, you need to pick out a color that matches or complements your existing acrylic paints. A slightly darker shade may help to hide any imperfections in the wall where cracks have been filled in. Be sure to test out a small area of the wall before you commit to a color.

Step 3. Fill in the Cracks

Use an artist brush, a small roller, or a toothpick to apply acrylic paint directly into the cracks in your wall. Make sure that it completely fills up each crack and smooths out any jagged edges. This will ensure that when the paint has dried, the cracks will be well hidden.

Step 4. Cleaning

Once you’ve finished filling in the cracks, use a damp cloth to clean up any excess paint that may have seeped onto the wall. Be sure to remove all of the paint and leave no trace behind.

Step 5. Dry and Repeat

Leave the filled-in cracks to dry for at least 24 hours before you repeat this process. This will ensure that the paint has had enough time to fully cure and bond with the wall. You may need to do multiple coats of paint to completely fill in any deep or wide cracks. Once you’re done, your walls should look as good as new. 

How to Prevent Acrylic Paint from Cracking

Acrylic paint can crack when it dries, leading to an unsightly finish. However, you can take several precautions to prevent this from happening. Here are some ways to prevent acrylic paint from cracking:

i. Use the right paint

Choose an acrylic paint formulated for working on canvas, wood or fabric. Oftentimes, artists confuse acrylic pour painting and brush painting. 

Look for a product designed to be flexible when dry and less prone to cracking than thinner paints that are made for paper surfaces, such as posterboard or paper mache. 

ii. Thin the paint properly

If your acrylic paint is too thick, it can crack when it dries. Use water to thin your paint down to the right consistency and test it on a scrap piece of material before you apply it to your project. If the paint starts cracking on the scrap, add more water.

iii. Avoid thick layers

When painting with acrylics, don’t apply the paint too thickly. Thicker layers of paint will take longer to dry and are more prone to cracking when they do. If you desire a thicker layer, try layering multiple thin coats of paint rather than one thick coat. Here are layering acrylic paint techniques you can use.

iv. Paint in the right environment

Acrylic paints dry faster in warm and humid environments, which can cause them to crack when they dry. To prevent cracking, try painting in a cool and dry place or use a fan to circulate air around the project while it’s drying.

v. Don’t overwork the surface

Once you’ve applied your paint, resist the urge to go back and add more layers or work on certain areas again. Too much friction on the painted surface will cause cracking and peeling.

vi. Apply varnish or resin

When your project is finished, apply a layer of varnish or epoxy resin over the entire piece to seal it and help prevent cracking in the future. This will also give it a more professional finish. Make sure to read the instructions on the varnish or resin you choose and apply it according to the manufacturer’s directions.

Common Myths about Acrylic Paint Cracking

A few painters and artists have created false narratives pertaining to cracking acrylic paint. These are some of the most common myths about acrylic paint cracking.

1. Acrylic paint cannot crack

While acrylic paints are more flexible than other types of paint, such as oil-based and latex paints, they can still crack over time due to age or poor application techniques. 

Age-related cracking occurs from the natural drying process of the acrylic binders in the paint. Poor application techniques can lead to cracking due to variations in the thickness of the paint, as well as improper curing.

See Also: Can You Mix House Paint With Acrylic Paint?

2. Cracking is only caused by age

While age can be one factor that contributes to acrylic paint cracking, there are other factors that can contribute as well. Poor preparation of the surface before painting, inadequate mixing of the paint before application, and improper curing techniques can all lead to cracking.

3. Only low-quality paints crack

This is a false statement. Regardless of the quality of the paint, if it isn’t applied correctly or allowed to age properly, it can still crack. It’s important to pay attention to the quality of paint when you purchase it, but equally as important is proper application techniques.

4. Acrylic paints should not be used on flexible surfaces

Though acrylic paints are more flexible than other types of paint, they should not be applied to surfaces that may flex or bend significantly over time. Examples of these surfaces include fabrics and rubber. Applying acrylic paints to these types of surfaces can result in cracking and peeling. 

5. Acrylic paints can be exposed to extreme temperatures

Exposing acrylic paint to extreme temperatures, whether hot or cold, can cause it to degrade and crack over time. Keep the area where you are painting free of extreme temperatures to avoid cracking. 

Acrylic paints should be kept in a cool, dry place, away from direct sunlight and extreme temperature fluctuations. 

Subzero cold can freeze the acrylic paint, making it brittle and prone to cracking. Avoid temperatures below freezing (32°F or 0°C).

Excessive heat softens the paint, leading to deformation and poor adhesion. Keep acrylic paint away from temperatures above 90°F (32°C).

6. Acrylic paints should not be applied over oil-based paint

Oil-based paints are much less flexible than acrylics and therefore can cause the acrylics to crack when applied over them. It’s important to properly prepare the surface before applying acrylic paints and only apply over surfaces smooth and free from oil-based paints. 

7. Acrylic paints can be mixed with other mediums

One of the advantages of acrylic paint is that it can be mixed with other mediums and additives to create different effects and textures. However, it’s important to be aware that certain mediums may cause the paint to become brittle or crack over time if not used correctly. 

Follow the instructions for any additional mediums before mixing them with acrylic paint.

Why Is My Acrylic Paint Cracking on Shoes?

If you’re experiencing cracking, it may be due to factors such as inadequate surface preparation, applying paint too thickly, using low-quality paint, or omitting a proper sealant.

To learn how to keep paint on shoes, ensure the surface is clean and primed, apply thin and even layers of high-quality acrylic paint designed for flexible surfaces, and seal the finished design with a suitable sealant to prevent cracking.

How to Store Acrylic Paint

To ensure your acrylic paint lasts for years, it is important to store it correctly. Here are a few tips to help you: 

Proper storage techniques

The right storage can help prevent the paint from drying out or becoming contaminated.

• Keep your acrylic paints in a cool place, away from direct sunlight and heat sources such as radiators or fireplaces. 
• Tightly close the container after using it to prevent air from entering the can. 
• Make sure you store the paint in containers that are made specifically for acrylic paint, as other materials may react with the paint and cause it to spoil.
• Store your acrylic paints away from any products that contain solvents, such as mineral spirits or turpentine, as these can damage the paint. 
• Place your paint on a shelf away from children and pets. 
• If space is an issue, use a tiered system to keep the paints organized. 
• Store your acrylic paints in containers that are easy to label and access. 
• Before you store them away, make sure all of your paintbrushes have been cleaned properly so they don’t contaminate the paints. 

Shelf life of acrylic paint

As acrylic paints are water-based, they are less prone to fading or discoloration than oil-based paints. However, this doesn’t mean that the shelf life of acrylic paints is indefinite; it’s important to understand the factors that affect its longevity. 

Light, temperature, and humidity all play a role in the longevity of acrylic paint. In general, acrylic paints stored in dark places at room temperature can last up to two years when properly sealed. However, if exposed to too much light or direct sunlight, it can cause the colors to fade and lose their vibrancy. 

Signs of expired paint

Here are some signs of expired paint:

• Strange odor: If the paint has a rancid, musty, or moldy smell, it is likely expired.
• Separation: When paint expires, the pigment and other components separate, causing lumps, chunks, or liquid to form at the bottom of the can.
• Clumping: Paint that has been sitting for a long time may have dried or clumped on the surface or around the rim. Here is how to fix clumpy paint.
• Thick consistency: Expired paint may have thickened over time, making it difficult to apply evenly.
• Discoloration: Paint that has expired may appear discolored, with a change in hue, or darkening.
• Irregular texture: If the paint appears grainy or gritty, it may be expired.
• Ineffective results: If the paint does not adhere to the surface or does not cover as well as it should, it may be expired.
• Settling: When paint sits for a long time, the heavier particles settle, and the thinner liquids rise to the surface, causing inconsistency in color and texture.

FAQs

Recap: Save Your Acrylic Paint from Cracking

Knowing how to save your acrylic paint from cracking can make all the difference between having a masterful and unique work of art and a cracked, brittle mess. But if you already experience issues with your acrylic paints cracking, follow the steps I have discussed to reverse any damage done.

Remember to start by examining the surface on which you’re creating your masterpiece; check its moisture retention capacity, flatness, and rough surfaces. Be mindful of the thickness of your paint layers and apply thickening mediums when necessary. 

With these tips and tricks in mind, you should be able to preserve the integrity of your artwork for years to come. However, if you need further assistance with why your acrylic paint is cracking in addition to quick solutions for correction, don’t hesitate to consult a professional in the field.