How to Dispose of Leftover Paint

For years, I stored all of my leftover paint in the garage.  We had several shelves full of half-empty gallon and quart size cans.  About this time last year, I decided that needed to change.  Not only were they taking up valuable garage space, but it turns out that paint goes bad after being stored outside for just a short while.  I felt silly for not realizing that.

So instead of storing the new cans I have more recently acquired in the garage, they now take up residence on top of the cabinets in my laundry room. It’s a great solution for the new paint, but I was left with a conundrum of how to dispose of the old paint.  You shouldn’t simply throw it out with the weekly trash, as it presents a hazard to the sensitive environment.

In many areas, you can take your half-full cans of paint to be disposed of in hazardous waste collection facilities or recycling centers.  You can find a place in your area by visiting

It’s also quite easy to harden leftover paint to make it okay for curbside pick up.  Now, I’m certainly no expert, but I understand that most municipal trash pickups will collect dried latex paint.  I have heard that you can use mulch or cat litter to harden the paint, but I just picked up a package of Homax Paint Harder for a few dollars at Home Depot.

To use the paint hardner, you simply dump the powder into up to 2/3 gallon of paint.  I had about a quart of paint in a plastic box that I needed to harden, so I just poured the powder into it.

With a stir stick, I stirred the powder into the paint until it started to thicken up.

After about 15 minutes, it had hardened to the consistency of thick oatmeal.  The wonders of chemistry!

At this point, you can simply scoop the hardened latex paint into something like newspaper and throw it away on trash pickup day.  Your cans can then be recycled.

Oil-based paint cannot be disposed in the same way.  Instead, it does need to be taken to a local hazardous waste facility.

Now I just need to buy about 30 more packets of paint hardner to finish up the rest of the paint left in the garage!  What do you do with your leftover paint?  Have you ever used a paint hardener?

Filed Under: Paint Your Walls

About Lindsay Ballard

Lindsay Ballard is a former college mascot turned political geek turned DIY fanatic who is conspiring to live in a Technicolor dream world. Her designs are bold and graphic, while her spirit is fun and full of color. Lindsay chronicles her projects and design ideas here at Makely, where she shares daily tutorials and inspiration. Lindsay lives outside of Austin, Texas with her husband (Tom), children (Zack and Emma) and dogs (Jack and Duke).


  1. Sherry (BTLover2) says:

    I’ve always wondered about this theory. Now I realize you are not a scientist and you may not know the answer to my next question, but I just have to ask: What does the hardening do that makes it safe for disposal? Won’t it still some how get into our eco-system? I’m obviously clueless but it seems like a water-based paint would still eek into our environment hardened or not. Either way I’ve got a huge job ahead of me just like you!! Thanks for the information!

  2. So cool! I always seem to save my paint for later, never use it, and then throw the crusty mess away. Obviously their is a better way. I haven’t done much painting honestly, so I haven’t thrown much out. We are FINALLY painting our house (no kitchen since Sept… wow), and was honestly wondering about this just Saturday. Thanks…

  3. I’ve desperately got to do this! I’ve been holding onto gallons and gallons of old paint because I didn’t know how to properly get rid of it. Can’t wait to have some of that space back!

  4. I’ve been hoarding our old paint because I had no idea what to do with it/how to dispose of it and was afraid of violating some be-kind-to-the-earth biohazard code. Good to know about the cat litter!

  5. Did you know that you can also donate leftover paint to a habitat for humanity resale store? Its actually where I go to get paint for small projects because its cheap and it helps fund houses for those in need

  6. We have save our paint and take it to our local Tox Drop site, which is open twice a month and they safely dispose the paint. We also drop off light bulbs and batteries.

  7. Another great place to donate leftover paint is to your local community theater or HS drama department. They are often in need of small amts of paint to paint sets with

  8. We have been told by our waste disposal dept. to just leave the lid off the can and let it dry up if it is latex paint. Of course, if you have half a can, that would take forever. Be sure to put it in a well ventilated space.

  9. I just did this last weekend when clearing out the garage at our old house. I had a handful of the same paint hardener packets, but had dozens of paint cans. I also used the bag of kitty litter that my husband already had from an oil spill, and it worked just as nicely as the hardener. I let them sit overnight, and then placed them in the garbage. Kitty litter is much cheaper!

  10. This is very good to know! I don’t paint often but the previous owners of our house left many gallons in the garage. Guess I’ll go buy some kitty litter!

  11. We have an old tote on our back porch under a bench I made from a pallet. We take the paint cans, with the lids off, and let them sit under there until they harden. It doesn’t take to long and then we just toss them. And it’s free.

  12. Thanks so much for this, Lindsay! Happy Monday!

  13. I just got rid of 60 partial gallons and over 80 partial quarts (I am a painter). I used a gritty oil-absorb product that was cheeper than kitty litter and way cheeper than the hardener. My paint was 7-12 years old and not useable. However, you can donate to places as mentionedabove along with Craig’s list or freecycle…the cheepest idea yet!

  14. I drop it off at our local landfill ;D We have a chemical recycling there…that’s where I get most of my paint. I painted the entire house (except for the loft, middle son’s BR and master BR) with paint from the landfill. It cost me a total of $5…I found a gallon of Pratt & Lambert paint at the landfill & took it back to the Ace hardware that it was originally purchased at to have them adjust the color. Cost me $5 & they threw in a new can. I want to try to replicate the color for this house. I like to grab all the white paint down there that I can, then adjust the color to suit me.

  15. I’ve used that stuff and yes I too wish more came to a container. We had about 40 gallons on paint “left” for us when we moved into our house. I had to get rid of them!

  16. I’m in Seattle where we’re crazy about our environmental stuff. That being said, you can do this same thing for much cheaper by using cat litter. I’m a property manager and after consulting with the dept of ecology, this is how we’ve been advised to dispose of our leftover paint. Once it dries — doesn’t even have to be 100% solid — it’s perfectly safe for disposal/curbside pickup.

  17. Verna Odom says:

    I wish I had read this last week! We had around a dozen can to dispose of and we poured it out on a plastic dropcloth, spread it around and let it dry. It took awhile, but it worked. Kitty litter or hardener would have been much neater, but not as much fun! Thank you for the information.

  18. When organizing our basement, we had over 10 cans of paint to get rid of. Our township would not take latex paint as hazardous clean up so we opted for Craigslist. I have never had so many responses so quickly! Maybe because it was free, but I had a drama department, an artist, and regular people just wanting a change contact me within minutes!