Why is My Acrylic Pour Cracking?

Acrylic Pour Crack and Crazy Large
Cracks on a Tree-Ring Acrylic Paint Pour

For an artist, there is almost nothing worse than creating a beautiful painting, setting it aside to dry, and coming back to find cracks in your masterpiece.  Unfortunately, almost every artist that uses acrylics, including myself, will experience cracking in their art at one time or another.

So why is your acrylic pour cracking?  Cracking occurs in acrylic paint pours when the top layer of paint dries faster than the underlying layer.  As the bottom layer dries,  it pulls at the semi-hardened skin on top and when the force is too much, a crack is created.  Newly formed cracks will continue to widen until the paint is fully dried.

While cracking is sometimes unavoidable, there are a few things you can do to limit the possibility of cracking.  In addition, if a painting does crack, you can potentially salvage the painting by using some of the recommendations below.

In Depth Look at the Causes of Cracking

If you are reading this blog you have, most likely, already had a painting crack.  I can definitely feel your pain.  Don’t be too discouraged though.  As I mentioned before it is bound to happen to all artists.  Once you understand why cracking happens, you’ll be better prepared to reduce the change they happen again in the future.

Paint Consistency

The consistency of your paint has a tremendous affect on potential cracking when the pour paints dry. 

Paint is Too Thin

Very thin paint mixtures, especially those diluted with excess amounts of water or alcohol, are prone to cracking because there is not enough binder in the paint, and/or paint medium, to hold everything together once dried

Alcohol and water do not contain any binders.  Because acrylic paint is water soluble, these additives also tend to break down the binders in the paint.  Small amounts will not have enough of an effect on paint and are valuable to control consistency.  Too much of either will increase the potential of cracking.

With thin paint, the top coat tends to dry very quickly.  The plastic/polymer binders, which hold dried paint together, accumulate on top and form the skin during the first part of the drying process.  

With thin paints, there is less binder to hold the paint together when dry.  Having less binder reduces the stress that the semi-dried, but uncured, top skin can handle.  The stress of the bottom coat volatiles evaporating can cause the top to “buckle” and break, which is why you see cracks.  The paint below will then dry and contract sideways, expanding the crack. 

Paint is Too Thick

Using acrylic pour paint that is too thick can have a similar effect that thin paint has.  Paint that is drying is loosing it’s water and solvents due to evaporation.  Water and solvents are what makes acrylic paint “thick” looking compare to when it is dry.  

With very thick paint, as with thin paint, the top layer of pain dries the fastest and forms a skin.  The paint underneath takes longer to dry.  When the paint is too think, there is more contraction happening as the water and solvents evaporate and move out of the paint.  This causes stress.

.Acrylics were made to handle some stress, which is why they are considered more durable and flexible than other types of paints.  However, when a very thick coat of paint dries and the volume of paint begins to shrink due to evaporation, that stress level can exceed what the dried top coat can handle and cause cracks to form.

Paint of any consistency, applied in a very thick layer, will also increase the likelihood of cracks forming during the drying process.  Coats of too-thick paint are more common in the center of a stretched canvas painting surface where the canvas sags  in the center due the the weight of the paint.

Environmental Variables

How fast the paint dries can have a significant impact on cracks forming.  As was mentioned previously, the top layer of paint drying too rapidly in relation to the drying speed of the bottom layer is a surefire way to increase the potential of cracks.

When a painting dries in a location that is too hot, the layers will tend to dry and different rates.  Similarly, if there is not enough humidity in the air, the drying process for the top and bottom layers will happen at much different rates.  

Because acrylic paints are made of water and water based solvents, freezing temperatures will most likely cause cracking and other undesirable affects.

The amount of air that circulates when your painting is drying can also increase the drying time of the top layer, while having less influence on the bottom layer’s drying time.  Again, this difference in drying times between layers of paint increases the chance of cracking.

You can read more about the drying process of acrylic pour paintings here.

Prevent Cracking In Your Painting

Now that you understand what can cause cracking in your acrylic pours, how can we prevent it from happening?  Try some of the steps below:

  • Ensure your paint mixture has enough binder.  Try thinning your paint with a medium with binders like Floetrol, PVA glue, or professional mediums, in addition to water.
  • Make sure your paint is not to thick and not too thin.
  • Add a retarder to slow the drying process.
  • Adjust environmental variables detailed here under the Slowing Down Dry Times heading here.
  • Use higher quality acrylic paints.
  • Pour off more paint to keep from having too thick of a coat on your painting surface.
  • Try layering multiple thin coats instead of doing one big thick coat if possible.

Fix Cracking In Your Painting

Now that you have a cracks in a painting you want to try and salvage, what are your options?

Fill with Paint

The easiest and most practical option to fix that cracking in your pour painting is to fill the cracks in with paint. 

If you’ve saved paint from the original pour that is idea as it will match your pour perfectly.  Use a small paintbrush, a spoon, a child’s plastic medication syringe, or a zip log back with a small corner cut out to insert paint directly into the crack.  Be sure to add slightly more than the crack will take as it will shrink as it dries.

Another option, which I highly recommend trying at least once, is using a single color of paint.  This can be one from the original painting or a new color, like a metallic or pearlescent.  This can add some additional character to your painting and really make it pop out to the painting’s audience.

Leave it Be

Another viable option with a pour painting with cracks it is leave it be.  Many famous paintings have cracks.  Time, the elements, or simply moving the piece can create cracks.  Many people that appreciate art, also appreciate the imperfection of the work.

Sometimes as an artist we want everything to be uniform and perfect.  That isn’t always the best route to take.  Get the opinion of those around you.  This will help you disconnect yourself from what you “think” the painting should be and let you think more objectively about the beauty of what you actually have.

Scrap and Re-Pour

Another option you have is to just give up on the piece altogether.  There is nothing wrong with this option.  This is art people.  There is no right or wrong answer.

One of the best parts about acrylic pour painting is that once a painting is dried and cured, you have the option to pour over the top of the piece to create something new.  That way you get to enjoy the painting process TWICE for the same painting!  

Related Questions

Why is craze cracking?  When paint crazes, micro-cracks form and then are “healed”, or filled in, as the volatiles in paint mixture escape through these micro-cracks.  Similar to a scar on skin, these crazes look slightly different than skin around them and will reflect light making them more noticeable.

What causes paint to craze?  Crazing can be caused imperfections in the acrylic paint or paint medium, environmental variables, paint consistency, painting surface preparation, and many other factors.  Crazes form during the drying process.  Read more about the acrylic pour drying processes here.

David Voorhies

I took up acrylic paint pouring a few years ago after binging fluid pours on Instagram and YouTube. I love that a left-brained technology nerd like myself can create amazing art. Hopefully this websites allows you to experience how fun acrylic paint pouring really is. See more about me here.

38 thoughts on “Why is My Acrylic Pour Cracking?

  1. Thanks so much for all advice. It’s totally increased my knowledge and also put my results in perspective. I was gutted to wake up this morning to see my best ever pour had cracked, when I’d been falling more in love with it each time I checked it the previous day. But I’ll just persevere and enjoy the process. I only took up painting a year ago at age 70 and it’s the highlight of my week! Thanks again .

    1. You are most welcome. I am sorry to hear your painting is cracking. If you have mostly big cracks on only a few cracks you could try filling them in with a complementary color or a neutral color to give the piece some pizzazz. If you decide to paint over it make sure you fill in the gaps and let it dry first or it will causing odd mounding in the new painting.

      1. I’m trying to use white house paint as my base and it’s cracked both times I’ve tried it. I though it was to thick the first time so I thinned it with water for the second time and possibly thinned to mich, I’m not sure. Any advice on using house paint successfully as my base?

        1. I’ve had similar results with white house paint. Not sure what is it about white specifically. I normally use a bit of Liquitex pouring medium or glue-all when I mix whites to help keep this from happening. People like Elyse Fournier (YouTube) use house paint as their base coat with quite a lot of success, especially for pearl cells on the outside of their paintings. There is definitely a slight difference between latex house paint and acrylic artists paints and as a former house painter I can tell you that anything more than a tiny coat of latex paint is going to crack.

    2. When you varnish or seal the paint will the presence of the cracks be eliminated? Or is it recommended to fill them before you seal the canvas?

      1. Cracks will still show through finishes. A thick coat like resin will remove the texture of the crack because it is so thick but it will still be evident when you look inside at the painting. Very thin finishes like a varnish will let you see the texture and won’t fill in the cracks at all.

        If you don’t like how they look, you’ll want to fill them in before you finish your painting.

  2. Thanks for the article and all the information.
    It’s been really helpful.
    I personally like the cracks and think it adds character and depth to my paintings.
    Not sure my client will agree though

    1. So true. I have filled in some of my cracks with complementary colors and they really do create some awesome interest to the work.

  3. Thank you
    Your article helpful
    Before was everything gone good, one time I shucked
    Now I tried twice and the crack showed agin 🥺

    1. Acrylic paint pouring is a two-edged sword. Amazing when it works, and heartbreaking when it doesn’t. Keep a journal of your paint ratios and mixes and adjust slightly each painting to help you narrow down what is causing the problems. You’ll get it, I am sure you will.

    1. Spray paint is a tough one. I haven’t used it in my pour painting but I do have some friends that use it exclusively as their paint source. I know when you spray the paint you can get different levels of paint and the chemicals used to cause it to “spray” depending on how you position your can and how full the can is. Spray paint also would be affected by temperature, humidity, and thickness just like regular acrylic paint.

  4. So grateful you are here!
    I’ve just started pour painting and followed a recipe of 1x white paint 2x floetrol 3x Golden gac800. gorgeous painting dried fully cracked and crazed! Reading your wisdom, I did think the paint was really thin (I used a scale for precision ) but again I’m a newbie so just followed the directions.How would I thicken it? Add more paint? Could it have been the cheaper artists loft titanium white? Maybe the Gac800? LOL can’t wait to have experience in this. Can’t wait to try your fixes, thank you.

    1. Artist’s Loft Titanium White has a reputation for cracking when not mixed correctly. I use it still but always with another type of white (Artist’s Loft Flow Acrylic White or another brand). Also, 5 times the medium to paint ratio seems excessive unless you are using a heavy body super pigmented paint.

      My recommendation would be to start out at 1:2 paint to pouring medium ratio for student grade paints. Only add a slight bit of water. When you pull your stick out of the paint and it drips back in the cup make sure the “mound” it makes takes at least 1 – 2 seconds to disappear. Like warm honey is what you are looking for. Use that for your first few paintings then start experimenting with a bit thicker and a bit thinner. Every style of painting will be slightly different.

      Also, make sure you are not leaving very much paint on the canvas/surface. You don’t very much left on the canvas. Try looking up my article on How Much Paint to Use for Acrylic Pours to give you an idea of how much paint normal canvases take.

      Any lastly, keep painting. We all start out making tons of mistakes.

  5. Thanks so much for this – I’m a beginner so guessing I must have not added enough pouring medium… However, my (incredibly beautiful!) finished swipe also got extremely dark overnight. Like it went from a perfectly bright and plump shiny plum to an outrageously flat, dark and shriveled prune – ughhhhhh!
    Any thoughts on that extreme shift? Thx

    1. You probably have two problems there. First, pretty much all paints lose their brilliant wet look when they dry. This is just the fact of acrylic paint pouring. Putting a gloss or semi-gloss top coat will bring back some of the look. Using a more expensive pouring medium like Liquitex can help that a bit also since it dries more glossy than glue-all or Floetrol.

      Second, if the colors really got darker you might have too much pouring medium or water and your transparent and semi-transparent colors are drying and you are seeing the darker colors through those colors. That’t not always the case but it has happens to me quite a few times over the years.

      What pouring medium did you use and with what ratio to paint?

  6. I just had this happen to one of my paintings I loved. I realized it was the pouring medium I used too much water and now my fix will be to add some crushed glass and Pebeo mirror leaves over the imperfections to add characters… Great article thanks!

    1. That is an amazing idea for a save. I haven’t used many 3d objects or additives in my paintings but I definitely want to try more geodes and beach pours like that.

  7. Thank you for this article. So very helpful. I just started pouring a couple of months ago. To save money, I’ve been practicing on thin sheets of wood my husband cut for me (pouring with RTP paints). I’m wondering if that may cause cracking because air is not able to penetrate the underside. Your thoughts?

    1. Most likely it is exactly the opposite problem. I would assume it is cracking because the wood is pulling the water out really quickly and the binder doesn’t have time to dry evenly. Try putting on a very thin coat of paint and let it dry for a few days and then pour over that. You can also you a cheap gesso. Just make sure it dries completely first.

  8. So my girls have started their own business and do mostly pour paint canvases. I didn’t notice the cracking until they started putting their paintings in the basement to dry. We have used the cheaper paint though to mix with Floetrel. I am wondering if the problem is the basement and the cheaper paint. You mentioned using a high quality paint, but I didn’t see any recommendations. What would you recommend?

    1. This is interesting. The basement should slow the drying process if it is cooler than the rest of the house which should, in theory, reduce the potential for cracks and crazing. Are they leaving on a lot of paint on the canvas? Is the paint still moving quite rapidly when they finish? Generally with Floetrol you aren’t going to get the problem of the mixture being too thick just because the nature of the medium.

      When you say cheap paints do you mean craft paints? Are you at a 1:1 ratio paint to pouring medium?

      1. They have used a variety of paints like loft, apple barrell, craft smart etc.. I was wondering about switching them to winsor and newton paints. I heard those are great beginner paints.

        They don’t really have a particular ratio. They start with just enough floetrel to cover the cup and then 2 tsp of paint maybe. Then they added a little more and more floetrel and lastly add water. Maybe they are adding too much water? Maybe we need to make sure we are doing more accurate amount of floetrel to paint?

        1. Don’t worry about going to more expensive paint. Craft and Artist’s Loft will work just fine. Try doing a 1:1 ratio with paint to pouring medium. You should need little to no water with that ratio for craft paints and just a slight bit with a student quality like Artist’s Loft. When the paint runs of the stick you want it to create a mount and disappear after a two seconds (one second is a little too thin). That is a good middle of the road thickness.

          Use about 1 oz of paint per 25 square inches of canvas. That way you don’t have too much paint to begin with.

          1. We tried using less paint and water and doing a more 1:1 ratio. We will see how they turn out. The one we did today I thought had too much paint on it so since it was a swipe painting I just swiped some of the paint off in some areas. The one painting we have has some cracking on the very top on the white base. I took some paint/floetrel mixture to try and cover that up and put some on with a sponge brush, but as it dried I could still see the little bit of cracking. It’s not too bad, but should I have done something different like used my finger with just white paint?

          2. I usually scrape some of the stuff that I tilted/swiped off and drizzle it on the low areas and then tilt a bit more to get the excess off again. A palette knife of a craft stick works great for that. Definitley let me know if that latest pour has issues.

            FYI I have taken gold or other metallic paints (thinned slightly with water) and just dripped into into the cracks and let them dry. That is a quick and pretty way to save some of those paintings.

    2. I’m not the writer but I now use creative inspirations brand as my go to student grade paint. Have never cracked using it. I often use that brands color “cover white” for backgrounds even when I paint with better paints. It is a huge step up from apple crate, folk art and the like but isn’t expensive like many other brands.

  9. Good background on “why acrylics crack”. I haven’t tried it, but I wonder if you could add another clear finish layer over the painting? Would applying this layer fill the crack(s) and render these crack almost transparent?
    Could you pour a clear epoxy resin on the painting and have resin seal the cracks?

    1. A generous layer of resin absolutely would cover cracks. Many layers of triple thick or Gloss Varnish would also.

    2. You may be able fill it with resin if the paint was thick. I filled one with colored resin. The after that dried put a clear coat on top of it.

  10. I had one bad crack in the very center of a pour painting. I filled it with resin colored with alcohol ink in a contrast color. It was the first one of the group that sold. Sometimes the happy mistake really can attract a buyer.

    1. That is awesome. I’ve had a few people that preferred the cracks/crazes when I’ve filled them in with other colors (gold, silver, white, black, etc.) That is the beauty of art.

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