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How to Fix Lumpy Acrylic Paint

Lumpy paint. Nothing about that phrase exactly screams “ideal medium”, does it? 

Lumpy paint is annoying and can feel like a real piece ruiner; but you can completely avoid lumps and fix them if they’ve appeared in your painting. Don’t throw out that canvas just yet!

Lumps can present themselves in different ways, but are most noticeable when a piece has dried. The most common causes of lumpy paint are bad paint, incomplete mixing, or lumpy medium. If your painting is still wet, use a clean stirring stick to gently remove the clump of paint from the canvas. This may disrupt the paint around the clump, but at least your surface will be level. Read on to learn more how to fix lumpy acrylic paint.

What causes lumps in acrylic pour paintings? 

Lumps can present themselves in different ways, but are most noticeable when a piece has dried. The most common causes of lumpy paint are bad paint, incomplete mixing, or lumpy medium.

Bad Paint

We could write a whole article on how to identify bad paint…actually, we have! You can read all about bad paint right on our blog.

Paint really does go bad; it may not have a printed expiration on it like food does, but that doesn’t mean it has an infinite shelf life. The longevity of your paint depends on the brand, what’s in it and how it’s stored, which means some of the factors that cause paint to go bad are out of your control.

However, if you have paint that’s separated and won’t incorporate again by shaking vigorously, or if you open your paint and you smell a strong, bad smell, that is a factor you can control – don’t use it! Lumpiness is just one of the issues you’ll have in a painting if you use expired paint.

Bad paint doesn’t always mean expired paint though; it can also mean low quality paint. If you purchase very inexpensive paint, you may end up with lumps due to the ingredients and processed used to keep the cost down. The best way to avoid this is to do research online before you buy paint to see if other artists have used it, and if they have, what their experience has been.

Incomplete Mixing

Mixing paint is a tedious process. It takes time and a lot of arm stamina to make sure your paint is well mixed, but it’s completely worth it; if you have pockets of unmixed paint, you’re likely to find lumps in your finished product.

You should take, at the very least, 5 minutes to mix each color you’re using. Mediums like Floetrol and Liquitex Pouring Medium are white, and stand out in any color that isn’t white, so you can easily see if you have some unmixed areas. In white, this is a little more difficult, so we suggest erring on the side of caution and mixing a bit longer to make sure everything is combined properly.

Some artists like to pre-mix their paint and use it as needed; this is a great idea! If you choose to go this route, you can use condiment bottles for mixing and storing. You’ll want to store the paint mixture just as you would any other paint; completely sealed, and not in direct sunlight or extreme temperatures. You can even add your silicone to your paint mixture in advance!

Lumpy Medium

Floetrol is one of the most popular pouring mediums on the market, and for good reason; it works! However, Floetrol is also notorious for having lumps and clumps and some sort of stringy “things” in it, especially if it’s sat for too long.

Most mediums will tell you to shake vigorously before you use them…they really aren’t kidding. Like paint, mediums do separate over time and that can cause lumps in the medium. Shake the bottle like the success of your painting depends on it…because it just might!

 

You should also strain your mediums  This isn’t really limited just to Floetrol, either; you can strain any of your mediums to remove lumps. All you need is a large cup or bottle and a fine mesh paint strainer (sold at local paint supply or hardware stores, or Lowe’s). It takes time to strain the medium, and you’ll definitely want to strain the medium further in advance. However, it’s absolutely worth it to do this, since you can avoid a lot of lumps this way.

Make sure you shake your medium very well before straining!

How to Fix Lumps in a Freshly Poured Painting

Now, let’s say that you followed all of these directions, but you’ve still got lumps in your poured paint; that’s ok! 

If your painting is still wet, use a clean stirring stick to gently remove the clump of paint from the canvas. This may disrupt the paint around the clump, but at least your surface will be level.

If the lump is definitely just paint, and not the stringy clumps caused by defective or old medium, you can also use a clean stirring stick to gently break the clump apart and flatten it out. 

If the clump is caused by defective or old medium, you can use a clean stirring stick or sometimes a pair of tweezers to lift the stringy clump out of the paint. 

If there are just way too many lumps in your painting for you to be able to fix it, you can also scrape your painting if it’s still wet. You can do this with a bench scraper, spatula, or any other straight edge utensil you have. You don’t have to scrape the entire painting either; if you find that only half of the piece has been affected, you could scrape half and quickly mix up another batch of paint to pour, if you catch all of this within about ten minutes time.

If you must scrape the entire piece, the canvas isn’t lost! Wait for about a week for the canvas to fully dry after having had paint on it, and then you can use it to pour a new piece.

How to Fix Lumps in a Cured Painting

Fixing lumps in a cured painting can be a bit more difficult, but again, not impossible.

If you’re planning on sealing your piece with a thin sealant like Polycrylic, having a bumpy surface probably isn’t ideal. In this case, you can sand down the acrylic bumps until they’re flat with the rest of the painting; you will need to touch up the bumps with paint or an embellishment like gold leaf.

If you plan on sealing with a flood coat of resin, you don’t necessarily need to flatten out the bumps – you can seal over them. A flood of coat of resin is thick, and will even out the surface of your piece. Unless your bumps are very high, one flood coat should be plenty to hide any bumps on the surface.

Conclusion

Lumps and bumps in acrylic pours are avoidable, but fixable too! If you don’t catch them when you first pour your painting, there are ways to fix them afterward…don’t throw out that canvas! We know that seeing a bumpy texture can be extremely frustrating, but the piece isn’t a total loss.

Remember; if the painting is still wet, and you have a lot of bumps, you can use a bench scraper or other straight-edge tool to scrape the wet paint off of the surface so you can use it for another project.

If the painting is dry, and you have a lot of bumps, you can use sand paper to sand down the bumps and use extra paint or embellishments like gold leaf to touch them up.

If the painting is wet and there are only a few little lumps, carefully pull them out with a clean stirring stick or if it’s stringy medium, you can use a pair of tweezers.

There’s always a solution to fix a misbehaving painting; don’t give up! And, if you have questions, make sure to join our Facebook Group where you’ll find almost 100k other artists who can give you real-time advice. Check out one artist’s experience with lumpy paint below!

 

Fixing a Loved, Lumpy Painting with Deby Coles

I loved this painting SO much when it was wet and was so annoyed with myself when the negative space dried all full of lumps and bumps. I hadn’t strained the paint, and although it looked OK wet, once the paint dried, it was covered in lumps like the painting had measles. In this video, I am going to try to repair it.

How to deal with lumps in your dried acryli painting. Video process for removing the lumps and bumps on a dried painting, for a glossy smooth finish.

 

All the lumps and bumps on the surface of the original painting

How to fix it? I am going to try to sand down the lumps and bumps and then repaint over the purple with probably a black. Let’s give it a try and see what happens!

Materials used in this project:
Old painting with lumps and bumps from this project
Wet or Dry sand paper(220 grit)
Cardboard support to prevent stretching
Black paint to cover the purple
Fine mesh mini strainer
8oz squeeze bottles
Polycrylic gloss protective finish

I’m so happy! The painting is saved. In fact, it is now so smooth and glossy that the surface is like a mirror and its really difficult to get a photo of it, without seeing glare from the window or even my own reflection! It took a little bit of effort and quite a bit of time, but in the end I probably like the painting more with the black than I did originally with the purple. So if something similar happens to you, know that you can sand down those lumps carefully, repaint, varnish and you are good to go!

I loved this painting SO much when it was wet and was so annoyed with myself when the negative space dried all full of lumps and bumps. I hadn’t strained the paint, and although it looked OK wet, once the paint dried, it was covered in lumps like the painting had measles. In this video, I am going to try to repair it.

How to deal with lumps in your dried acryli painting. Video process for removing the lumps and bumps on a dried painting, for a glossy smooth finish.

Firstly, why does this happen? Hmm, I really can’t say why some paints just are lumpier than others. I’m not convinced that it’s just about the mixing, because I would have mixed the purple the same as the other paints. I used the same ingredients, the same ratios etc – sometimes some paints are just more lumpy than others. Until now, I’ve found it with my white paint and usually will strain that, but I’ve never had it this bad in a color before. Lesson learned.

oxo good grip strainer
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How to avoid it happening in future. Remember to strain the darned paints. I mix my paints in a small jug and then transfer them to the squeeze bottles, so I just need to remember to strain them through my new fine mesh strainer from the jug into the bottle. Then all will be well. It really doesn’t add any time and can save a lot of trouble later. I need to get into this good habit.

All the lumps and bumps on the surface of the original painting

How to fix it? I am going to try to sand down the lumps and bumps and then repaint over the purple with probably a black. Let’s give it a try and see what happens!

Materials used in this project:
Old painting with lumps and bumps from this project
Wet or Dry sand paper(220 grit)
Cardboard support to prevent stretching
Black paint to cover the purple
Fine mesh mini strainer
8oz squeeze bottles
Polycrylic gloss protective finish

I’m so happy! The painting is saved. In fact, it is now so smooth and glossy that the surface is like a mirror and its really difficult to get a photo of it, without seeing glare from the window or even my own reflection! It took a little bit of effort and quite a bit of time, but in the end I probably like the painting more with the black than I did originally with the purple. So if something similar happens to you, know that you can sand down those lumps carefully, repaint, varnish and you are good to go!

30 thoughts on “How to Fix Lumpy Acrylic Paint”

  1. Marie Gamalski

    Deby… if it ever begins to sag, just get it wet under the faucet, let it drip dry and it’ll tighten right up. I usually always do that on finished pieces just to tighten everything up before sale!?

  2. I have those bumps in mine. I though they were air bubbles. I’ll strain the paint from now on. Thanks. Mine aren’t in negative paintings though. Will anything terrible happen if I just varnish over them?

    1. Nothing terrible will happen, but varnishing won’t cover them up at all. They will still be there. What a shame.

    2. It’s just some texture, right? They are my best paintings yet — so I’ll just hang them in my office. 🙂

      It was a new type of paint: Lukas — really great price — and decent colors but clearly lumpy.
      I wondered why the torching didn’t remove the air bubbles (head smack) — but live and learn. Your site has been so helpful. Thank you for sharing. Your course is great too.

      I’m more worried about the bumps making the painting more susceptible to damage –but if I can varnish over them, hopefully that will protect them.

    3. Christina Gudgeon

      I poured resin over mine but the lumps still show. I will sand slightly in future if I get lumps but straining first would help.

  3. Deborah Pouliot

    Hi Deby! This recently happened to me but unfortunately, I didn’t try to sand it before I put the gloss coat on. I think it still looks okay, especially if you don’t look at it at an angle in the light ;-). From now, I will be sure to strain my paints so this won’t happen again. The main reason I’m commenting, is because I wanted to suggest using sanding blocks or pads. I think they’d be easier to handle and they come in different grits – plus, they can be used several times before they wear out. Anyway, thanks so much for your helpful, informative and inspiring videos.
    Cheers,
    Debs
    xo

    1. Thanks for the tip. Hopefully its something I won’t need to do again, but if I do, I will see if our DIY stores on the island carry them.

  4. Hi Deby,
    I’m not having any luck trying to repaint over a previously painted canvas, even though I clean them very well with cornstarch then Dawn. Every time, I get lots of crazing, no matter how I vary the pouring recipe or viscosity.
    Do you -or your readers- have any experience solving this problem?

    1. How long are you leaving them between pouring? I’d suggest at least a month for the original paint to fully cure before pouring over, or the new paint and soften and loosen the original paint and that might contribute to the crazing or cracking of the new layer.

    2. Yes, I’m thinking that might be what is happening. The paintings are more than a month old, but perhaps I’ll try waiting a bit longer. I’m also considering sanding the surface a bit and letting it sit a couple of months.
      Thanks!

  5. Hi there. My first time in. Thanks for your tips. I get the bumps and I was wondering if it could be the gesso on the canvas. There are cotton textures you can see before pouring. If so, maybe sand before pouring??

    1. In my case it was certainly in the paint itself, but yes, gesso can also add some unwanted texture underneath a painting if you apply it thickly, but at the same time it can also hide the texture of the canvas if you don’t like to see that in your art. I like the canvas texture, so usually don’t gesso first.

  6. Hello I enjoyed your videos and I will try this but was wondering when you do the poly acrylic do you paint it on or do you pour it on

  7. Thank you for sharing this method. However, the “texture” in the painting adds to the look in my opinion ~ in fact, that’s one of the things that makes this technique unique. If the “texture” is distracting, I would sand it out, but otherwise ~ leave it be.

  8. I use a medium size sponge brush to apply the polycrylic. I put 3-4 cats on going horizontally on the first coat, vertically on the next then repeating. Between coats it your sponge brush in a ziplock by and seal it up. Don’t wash it out. Next time you use it the brush will still be soft and ready to go. It will keep aweek or more in the bangs I’ll last for several uses.

  9. Carlotta Lalonde

    This was my favorite painting and info tutorial and I have seen many. Deby is a great instructor and painter and I plan to follow her advice now. She is part genius and part angel. I so want to be able to paint elegantly and give away to family and friends to make their life richer.

    Thank you so much, Deby. You are a blessing to all.

  10. Hi all. I love pouring it’s so addictive and the paint has a mind of its own. I sometimes use the finished pour as a background or see what images step out at me and outline them.
    I tried flow aid for the first time this weekend, and had enough mixed paint for two pieces. I was giving it praise because of the creamy consistency and that I had enough for two. Now one is full of lumps and the other has no lumps, it’s like it caught the measles. It was a good painting too because an eagle image appeared in it. I thought nothing of it because I was taught never to reject anything I create, because others have in the past and when it was discovered it was more important than the good one because of the error. It could always pass as texture I guess and they have braille paintings too, but how come the same mix be good on one painting and bad on the other?

  11. I use pantyhose! Just cut a piece out of them, stretch it across the top of the paint bottle and replace the lid. It’s been working well for me. ????

    1. I am a new painter and this is the second time I have heard this tip! You can bet my paints are going to be dressed up in their pantyhose! ????

  12. Well I’m a newcomer. I’m just now beginning the process of buying my supplies. I walked into the paint department of Hobby Lobby and was immediately overwhelmed! So here’s my question. How he heck do you know what brand to buy? Do you get acrylic craft paint in those tiny bottles or big tubes? And what about those expensive ones or the metallic ones? Do you buy a big box of basic colors? Help! Love all you artists out there that are so willing to share your journey with us wannabes!

    1. I’d start with inexpensive brands like FolkArt, which you can get for less than $1 a bottle. I’d pick up a set of primary and secondary colors, then a few metallics if you think you might need them.

      You can also find a pearl paint which you can mix into any color to add a pearlescent sheen to it.

      You can play with thinning your paint down with water, mod podge, or varnish like Triple Thick.

      Get some cheaper brushes for just starting out.

      Pick up some small lidded jars from the dollar store and experiment with mixing colors using those jars.

      Try to limit air exposure to the bottled paint.

      Make sure to not pour paint or your brush cleaner water down your drain; Acrylics are a plastic and they’re harmful to your plumbing, not to mention the environment. I use kitty litter to dispose of old paint and brush water.

      Good luck!

  13. Thanks for the tutorial! I think the lumps in acrylic paints are actually dried paint. Acrylic is basically a plastic suspended in water, and after you expose paint to air, it dries pretty quickly. I’ve found that painting in a humid environment helps reduce the amount of lumps a little. I think it’s also important to try to expose the paint in the bottle to air as little as possible. I used to just unscrew the cap from my FolkArts and use the paint from the inside of the cap, especially on smaller projects, but that led to tons of lumps. I ended up getting some little clear lidded plastic jars from the dollar store and I’ll pour a little bit of whatever paint I need into a jar. If I lose that little bit, it’s not such a big deal as having an entire bottle lumpy and stringy.

  14. Loooooooove the panty hose idea , hate to go out just for a strainer and want to ———POUR !!!!!!!!!!!

  15. So good to see Deby again! I really miss her videos. Was always one of my favorites.
    This is very good advice. Thanks

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