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8 EASY Ways To DRY Paint Cans For Disposal (How To Harden Paint)

Ready to get rid of old paint in your garage or basement? Here’s 5 EASY, FAST, CHEAP, and SAFE ways to dry paint cans for disposal.

How To Dry Paint Cans For Disposal

Somehow, every 5 years or so, I end up with a big collection of old paint that I can’t, or won’t use anymore. And, while recycling paint is great, the closest drop off for me is a 1/2 drive away.

So, it doesn’t make much since to try to recycle some mismatched paint by driving so much to do it.

Luckily, there are some pretty cheap and easy ways to harden paint for disposal. In fact, you probably already have something you can use.

Image of old paint cans for a post about how to dry paint for disposal or harden paint for disposal.
Safe way to dispose of paint!

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Let’s get to that list of ways to dry out paint for disposal.

How To Dry Out Paint Cans For Disposal (Video Steps)

Want to see how I tested these methods? Watch this video for a look at 6 of the ways you can dry paint cans for disposal. Scroll down to see the written list and tips.

Testing 6 EASY ways to DRY Paint Cans For Disposal (How To Harden Paint)

Ways To Harden Paint For Disposal

After checking the EPA recommendations and my state and local recommendations to safely dispose of water-based paint, I decided to test some of the recommendations to see which would work best.

Here’s how those tests turned out.

1. Kitty Litter

Every environmental waste recommendation website I checked recommended using kitty litter to harden latex paint.

And, I have to say, it was the fastest method I tried. Kitty litter works on water-based acrylic wall paints too.

Image of putting kitty litter in paint to harden paint for disposal.
I poured about 2 cups of kitty litter into about 2/3rds of a gallon of paint then stirred it with a paint stick.

For this test I poured generic clumping kitty litter into a half empty can of latex paint. Then, I used a paint stick to mix the kitty litter into the paint.

You want to mix it up well so that there is kitty litter mixed in with all of the paint. If it’s easier for you, you can pour the paint into a large, trash bag-lined cardboard box before you mix in the paint.

Once all of the paint is mixed into the kitty litter, let it sit in a dry place, or in the sun, so that it can completely harden. Mine was AS HARD AS CONCRETE in less than a day.

Image of dried out paint using kitty litter for a post about how to dry out paint with kitty litter.
By the next day, the kitty litter and paint mix was nearly as hard as concrete.

2. Sawdust

If you have a saw or two that gets tons of use, you probably have a HUGE bag of sawdust. For this test, I mixed 2 full drink pitchers worth of sawdust with about 2/3rds of a gallon of paint.

I had high hopes for this test. It seemed like sawdust would be a good way to dry out paint cans. But, after 2 days in my shady garage, it was still pretty wet.

So, I moved the paint and sawdust mix into the sun, on my driveway. Within 12 hours, that mix was completely dried out.

I highly recommend that you put your sawdust and paint mix in the sun right away to shorten the dry time.

Sawdust mixed with paint to dry out paint for disposal.
2 full pitchers of sawdust turned this paint instantly mushy. Putting that mix in the sun completely dried it out.

3. Newspaper

Here’s another cheap, fast, and easy way to dry latex paint for disposal. If you still get a newspaper, or newspaper ads, you can tear those into small pieces to mix into your water-based paint.

Newspaper is a pretty good way to harden paint for disposal. I mixed newspaper with paint then put it out in the sun. Within a day, it was completely dry and ready to throw out.

Newspaper mixed with paint to dry out paint for disposal.
Newspaper helps to absorb the moisture and dry out wall paint.

4. Plaster Of Paris

I didn’t see Plaster of Paris in my research as a way to get rid of old paint. BUT, I use plaster of Paris with latex paint to make DIY chalk paint. So, I know too much can dry out paint.

So, I grabbed my cheap carton of Plaster of Paris and poured a cup or more into my leftover paint. Then I stirred it up and left it sitting in my shady garage.

After 2 days, the paint was still pretty wet. So, I placed the mix in the sun. After 12 hours in the sun, the mix of Plaster of Paris and latex paint was completely dried out and ready for the trash.

Whenever possible, place your mix of paint and whatever you’re using to harden it in the sun to harden it faster.

Plaster of Paris mixed with paint to dry paint for disposal.
Pour in the Plaster of Paris then mix really well before setting it in the sun to dry and harden paint fast.

5. Air Dry

Two of the Environmental Waste websites I checked mentioned that 1″ of paint or less could just be left with the lid off. Then the air was supposed to harden it within 3 days. So, I gave that a try.

I left my can open for 3 days in my shady garage. BUT, it was still REALLY WET under a thin skin of dried paint. So, I popped it in the sun to dry it out faster.

I’m sure the paint would have dried out without the sun, if given a week or more. BUT, I want fast methods.

And, even with a lid off, a full gallon of paint will need to be left open for a month or more to completely air dry. So, this was my least favorite method, even though it technically works.

Does air dry paint for disposal?
After 3 days, this small amount of paint had a dry skin. But the paint underneath was still really wet.

6. Store-bought Paint Hardener

Of course, you can always buy store-bought paint hardener. It sells for around $4 for a package that can harden 3/4 of a gallon of paint.

BUT, if you have 10 gallons or more to do, that can feel like a waste of money. SO, I recommend buying a BIG, CHEAP container of clumping kitty litter instead. It works just as well.

Paint hardener can be mixed with paint to harden paint for disposal.
Store-bought paint hardener can also be used to harden paint for disposal.

7. Sand

I didn’t have any sand to try this method out, but a few websites suggested adding sand to your paint can help to dry paint out for disposal.

Again, I can’t say whether or not it works. But, you can always try it with 1 container to see if it works.

Sand can be mixed with paint to harden paint for disposal.
Supposedly, sand can be used to harden paint for disposal too.

8. Slow Pour

Here’s another completely safe way to dispose of paint. BUT, it might take a LONG time, depending on how much paint you have.

For this method, grab a big cardboard box, line it with a trash bag to prevent leaking, then pour in a thin layer of paint. Let that dry completely, then repeat until your paint is completely hardened.

Hard water-based paint safe for disposal.
Hard water-based paint is safe for disposal.

How Do I Dispose Of Paint Safely?

To safely dispose of water-based paints (latex and acrylic) you just need to harden it before throwing it in with your normal trash.

Water-based paints are non-toxic and NOT HAZARDOUS. You just need them to be dry to prevent them from contaminating soil and water.

Gummy paint that looks as thick as air dry clay is also safe for disposal.
Gummy paint that looks as thick as air dry clay or Playdoh is also safe for disposal.

How Long Does It Take Paint To Harden With Kitty Litter?

Paint mixed with kitty litter can harden anywhere between 1 hour and 12 hours, depending on how much kitty litter you use and the weather.

It will take a little longer for larger 5-gallon containers, in cold weather or high humidity.

Setting the kitty litter and paint mix in the sun can speed up the paint hardening. Spreading it flat on cardboard or a trash bag can also speed up the dry time.

How Much Kitty Litter Do I Need To Dry Paint?

I use 2 to 3 cups of clumping kitty litter to harden 1 gallon of paint. Just be sure to mix it well to be sure that all of the paint hardens. When you mix it, it’ll be a bit like thick oatmeal.

Image of old paint cans for a post about how to dry paint for disposal or harden paint for disposal.
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That’s it for how to harden paint for disposal. I hope this helped! Now, here’s a few more posts you might like.

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Thursday 4th of May 2023

I'm a loyal follower of yours and I love your thorough coverage and testing. This is a great example. I have a group of blogging friends who also do DIY projects. We like to find bloggers with high quality content to "hop" with. We are going to do a Christmas in July hop. If you have any interest in participating you would be great.

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