Skip to Content

Does Paint Thinner Expire? [How Long Does It Last]

Paint thinners are very useful in thinning or cleaning paint from various painting tools. Are you curious if paint thinners have an expiration date and how long their effectiveness lasts? We've gathered ample information to help with your queries.

Disclosure: We may get commissions for purchases made through links in this post.

The shelf life of paint thinners depends on whether they're sealed or how they're stored. Expiration could be from a few years to indefinite when they're unopened and stored in a cool, dry place. Upon opening, service life lessens due to evaporation.

Please keep on reading to learn more about paint thinner use and safety precautions. We've also included some of the most recommended paint thinners for you to try.

A can of unopened paint thinner, Does Paint Thinner Expire? [How Long Does It Last]

What Is A Paint Thinner?

Paint thinners are a range of chemical compounds or solvents developed to strip or thin paint from painting tools such as paint brushes. Typical samples of paint thinners are acetone, turpentine, and toluene.

A yellow can of paint thinner

This potent chemical thins down primers, stains, and oil-based paints. It makes it easier to cleanse paint from a surface or clean painting materials.

You can also use paint thinner to thin the color by decreasing the product's consistency to supply a paint sprayer or attain various finishes on an artwork.

How Long Do Paint Thinners Last?

Pouring paint thinner to a small cup

Paint thinners can last indefinitely if they remained enclosed and unopened. They can also last for several years depending on the chemicals or ingredients they contain.

If you put some of them in a can or closed canister, they can still slowly evaporate. These solvents can typically last for a day, and sometimes more.

Upon mixing paint thinner with paint, the thinner will start to evaporate from the exterior. The duration it takes will usually depend on the top layer.

Paint Thinner Usage

Here are the top four uses of paint thinners.

For Thinning Paint

Paint thinners are mainly used to reduce paint's thickness, especially oil-based paint. Thinning paint lessens the possibilities of paint imperfections upon application. Paint thinners also deliver a smoother exterior impression and a premium glossy effect.

Steps In Thinning Paint

  1. Select a suitable paint thinner with the paint you'll use.
  2. Mix the paint thinner with the paint to thin it.
  3. Ensure that the ratio of pigment to paint thinner is correct to avoid ruining the paint.
  4. Check the manufacturer's guide on the container to get the proper mixture.
  5. Measure and blend the paint and paint thinner.
  6. Add or lessen the quantity of paint thinner until you get the correct mixture.
  7. Test your mixture on a surface and check if it has a perfect consistency.
  8. Combine a more considerable amount of paint once you have the accurate ratio.
  9. Use your blend to your heart's content.

Safety Tip:

To avoid damage caused by the eroding effects of the paint thinner, use an appropriate container for mixing.

For Cleaning Painting Tools

Paint thinners are also used in cleaning tools and equipment like paintbrushes and trays. The chemical components of paint thinners help corrode paint for easier cleaning.

Steps In Cleaning Painting Tools

  1. Place an amount of paint thinner in a container.
  2. Soak the painting tools (paintbrush) and cloth repeatedly until the mixture gets through and corrodes the paint.
  3. Cleanse the tools in warm water with soap to separate the paint thinner and paint bits.
  4. Finally, wash and then dry the painting materials.

Steps In Cleaning Larger Tools Like Paint Trays And Cans

  1. For paint trays, you can clean them with a clean rag or brush.
  2. Dip it in the paint thinner mixture.
  3. Wipe or brush the dirt or paint off the painting materials 
  4. Wash in soapy, warm water and dry the tray or can.

Safety Tip:

  • Avoid using plastic containers as paint thinners may damage the plastic and spill through the container.
  • Always make it a habit to wear proper safety equipment such as gloves. 

For Stripping Paint

Paint thinners are not only great for thinning paint. These solvents are also your answer for removing paint from metal, concrete, and wood. Below are the steps in stripping paint from these surfaces. 

Steps In Stripping Paint

  1. Pick the most suitable paint thinner for the type of surface you'll use it for.
  2. Apply a light layer of paint thinner to the exterior with a paintbrush.
  3. Let the paint thinner stay for approximately 20 minutes to soften the paint.
  4. Use a wire brush for scraping if the paint is still a bit new.
  5. Scuff the paint off with a plastic scraper if the color is old.
  6. You should perform light sanding if you're removing paint on wood.
  7. Apply an extra paint thinner if all the color isn't removed with the plastic scraper.
  8. Clean the paint thinner with water and a cloth after clearing the paint.

Safety Tip:

Ensure you don't use excessive paint thinner to prevent seeping into absorbent surfaces like wood.

For Restoring Dried-Out Paint

One of the paint thinner's best uses is reconditioning dry paint. You don't have to throw away your dried-up paint, but you can restore it with paint thinners. Paint thinners consist of thinner medium and flow improvers, which help bring back their original consistency.

Steps In Restoring Dried Paint

  1. Start by pouring an ounce of paint thinner into the paint can.
  2. Depending on the paint in the can, you can add more or reduce the amount of paint thinner until your expected outcome.
  3. Use a stirrer or stick to stir the thinner and dried paint until it's too dense to mix.
  4. Add a half ounce to one ounce more of the paint thinner.
  5. Mix the paint color well.
  6. Add more paint thinner until you have thinned the dried paint and acquired the preferred thickness.

Safety Tip:

Put the open paint on plastic to shield your work exterior from paint stains.

Regarding Safety, Proper Disposal, And Storage

Painting equipment's on the table

People have many questions about paint thinners such as their proper disposal, safety, and storage. Let's tackle all of the most important stuff that needs to be addressed. 

How To Store Paint Thinner For Maximum Shelf Life?

Here are several must-do to achieve the maximum shelf life of paint thinners.

  • Ensure that you close the lid tightly and seal the container after every use.
  • Place your paint thinner in a dry and cool spot.
  • Keep away from children, pets, and flammable things.
  • Read the manufacturer's guide for the proper storage temperature.
  • Put your paint thinner in your garage, shed, or basement.
  • Ensure that the temperature doesn't become too hot, especially in summer.

How Do You Dispose Of Dirty Paint Thinner?

Painter adding paint thinner to his paint mix

Paint thinner is a harmful chemical, so you want to dispose of it carefully. In many cases, you'll be able to salvage some of the paint thinner by filtering it. You can let it rest until the gunk settles, then collect the clean paint thinner on top. Wrap up the remaining sludge in newspaper and throw it in the garbage.

If you have excess paint thinner that you need to dispose of, you can take it to a hazardous waste disposal area.

10 Paint Thinner Safety Precautions

Here are 1o paint thinner safety precautions you must always keep in mind and never forget.

  1. Use paint thinners in well-aired surroundings.
  2. Put on safety garments.
  3. Take immediate measures for first aid.
  4. Keep paint thinners far from acidic substances.
  5. Never mix paint thinners with materials other than paint.
  6. Stay away from heat and flammable materials.
  7. Avoid consuming food in the area.
  8. Don't use paint thinner as a general cleaner.
  9. Avoid smoking in the area.
  10. Cleanse your hands after every use.

What's The Difference Between Mineral Spirits And Paint Thinners?

Both mineral spirits and paint thinners thin and clean oil-based paint.

A paint thinner is mineral spirits but in a less polished state. It comprises other kinds of chemical solutions that cause it to have a chemical odor and be more flammable. Mineral spirits, on the other hand, are made of pure petroleum concentrates and have no add-ons.

Further differences between mineral spirits from paint thinners are that they are:

  • Less Toxic
  • Odorless
  • More Effective
  • More Expensive

Best Paint Thinners

Sunnyside Pure Odorless Paint Thinner

Click here to see this product on Amazon.

This Sunnyside oil-based paint thinner is Amazon's Choice. It's best for effectively thinning, dissolving, and removing oil and grease.

Best Features:

  • Zero odor
  • Easy clean-up
  • Perfect use in hospitals and nursing homes
  • Comes in a 32 fluid-ounce can

RH Adhesives HH-66 Thinner

Click here to see this paint thinner on Amazon.

This HH-66 paint thinner works well in any weather or conditions.

Best Features:

  • Colorless liquid paint thinner
  • Quick and easy clean-up
  • Quality and trusted brand since 1949
  • Comes in a 16 fluid-ounce can

Mona Lisa Odorless Paint Thinner

Click here to see this paint thinner on Amazon.

The Mona Lisa paint thinner can be effectively used in all kinds of varnishes, oil, and oil-based paints.

Best Features:

  • Odorless Paint Thinner
  • Perfect paintbrush and tool cleaner
  • Can be used like turpentine without any unpleasant smell
  • Comes in a 42 fluid-ounce container

Use Your Paint Thinners Well

A can of unopened paint thinner

 Upon learning how long paint thinners last and how to properly use and discard used thinner and rags, it's time to start your project. If you somehow forgot the vital things, just reread the safety precautions and tips to help you. So, go ahead and work safely.

Check out these wonderful posts about paint removal on wood and carpets.

How To Remove Paint And Stain From Wood

How To Get Paint Out Of Carpet [Inc. Oil-Based or Latex Paint]