How to Fix Lumpy Acrylic Paint

Lumpy paint. Nothing about that phrase exactly screams “ideal medium”, does it? If you too have wondered “how to fix chunky paint”, you have arrived at the perfect acrylic paint blog post!

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!

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.

If you have ever thought – Can acrylic paint expire? Then the answer is – YES, it does!

The paint really does go bad; it may not have a printed expiration on it as 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 leftover 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 acrylic paints.

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 processes used to keep the cost down. The best way to avoid having lumpy or dried paint in your ally is to do your research online before you buy your acrylic paints 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 or even dried old acrylic paint everywhere, 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 acrylic paint. 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 the airtight container vigorously before you use them…they really aren’t kidding. Like paint, mediums do separate over time and that can cause lumps in desired consistency of 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 acrylic paint strainer (sold at local paint supply or hardware stores, or Lowe’s). It takes time to strain the thick acrylic paint 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 a few drops of the paint around the clump, but at least your surface will be level.

If the lump is definitely just dry acrylic 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 of dried out acrylic paint apart and flatten it out. 

If the clump is caused by a 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 the 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.

Our Take

Lumps and bumps in pours are avoidable owing to some inherent acrylic paint properties, but fixable too!

If you vigorously shake your paint container, check a few drops of paint to see for signs of dried acrylic paint, you can choose to reactivate acrylic paint before using them.

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 sandpaper to sand down the bumps and use extra paint or embellishments like a 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.

 

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 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 it’s 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, and 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.

Firstly, why does this happen?

Hmm, I really can’t say why some oil paints just are lumpier than others. I’m not convinced that it’s just about the mixing in a bid to rehydrate acrylic paint, 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 lumpier 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.

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How to avoid it happening in the 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 it’s 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, and varnish and you are good to go!

FAQ About how to fix lumpy acrylic paint

1) What causes lumpy paint?

Lumpy paint can be caused by a few different factors, including using old or expired paint, not properly mixing the paint before use, or using a low-quality paint that has clumps or impurities. It can also be caused by painting over a surface that is not properly prepared or has debris on it.

2) How can you prevent paint from becoming lumpy?

 To prevent paint from becoming lumpy, make sure to strain it before using it. You can also add a paint conditioner or a small amount of water to thin it out and make it easier to work with. Additionally, make sure to properly store your paint in a cool, dry place and avoid exposing it to extreme temperatures.

3) Can you fix lumpy paint without straining it?

 Yes, you can fix lumpy paint without straining it. One method is to use a paint conditioner or additive, which can help smooth out the paint and make it easier to apply. Another option is to use a paint mixer attachment on a power drill to thoroughly mix the paint and break up any lumps.

4) What is the best way to strain lumpy paint?

 The best way to strain lumpy paint is to use a paint strainer bag or a mesh strainer. Simply pour the paint through the strainer into a clean container, and any lumps or debris will be caught in the strainer. This will result in a smoother finish when you apply the paint.

5) How can you get rid of lumps in paint once it has dried?

 Unfortunately, once paint has dried with lumps, it can be difficult to fix. One solution is to sand down the lumpy areas and then repaint over them. Another option is to use a paint strainer or filter when pouring the paint into the tray or roller. This can help catch any lumps or debris before they make it onto the walls.