Home Improvement Tips & Ideas
George asks,
After painting I have two partially used cans of latex paint. I know that in storage it will be evaporation of water, benzene, toluene, and formaldehyde which results in paint hardening in 3-5 years. Can the shelf life be improved if all the air in the cans to be stored were replaced with water to displace all the air?
I’ve never heard of your suggestion that filling a can of leftover latex paint with water to take up the air space to preserve it. And, it doesn’t seem it’d work all that well for storing paint anyway as the water will simply mix with the latex (water base paint)! I have a few other suggestions you may find helpful.
When it comes to storing paint and the life expectancy of leftover paint, most manufacturers will tell you that paint can last 2-3 years. My personal experience is that it can last longer. Success depends not only on where the paint is stored, but even more importantly the condition of the can.
The enemy of storing paint is simply – air. The more air that gets into that can, the shorter the life of the paint. So, the seal is key to storing paint for the long run. Here are a few things I have learned that can help.
First, when you open a new can of paint, don’t use a screwdriver. Instead you a paint can opener tool. Prying open the lid this way can bend the edge and make it more difficult to get a seal when the lid is replaced. It’s ok to use the screwdriver to carefully poke drainage holes in the bottom of the channel inside the can, but don’t use it to pry the lid off initially.
When you are done with the paint, use the brush to clean the seam as much as possible on the paint can and use a rag to wipe the opposing seam on the lid. Paint that dries in either area will prevent the lid from sealing completely.
TIP: In addition, paint that sits in the seam are can cause rust which can discolor the paint, a lesson I learned the hard way. Some years ago, I tried to touch up some woodwork in my home using paint from the same can I initially painted the wood with. I noticed that the color was slightly darker. It really bugged me for a while because I could not for the life of me understand why. The solution became appeared the next time I opened the can and noticed that a few flakes of rust had fallen into the paint. That small bit of rust was like a dye that spread throughout the can when I stirred it and resulted in a brand-new shade I was not planning on!
Next, cover the open can with a piece of clear plastic wrap (like Saran Wrap). This acts as a gasket and provides and additional level of seal protection preventing air from getting into the can.
Finally, place the lid on and then tap it down, gently at first, using a rubber mallet (prevents dents and damage to the seam portion of the lid). Once the lid is in place, hit it again more firmly with the rubber mallet to complete the process.
TIP: If you lay a rag over the can before hammering the lid closed, you’ll both protect the lid and catch any paint spray that might launch off the lid and land on you or your work area!
Once this is done, store the paint in a cool, dry area, that is not subject to temperature extremes. If you have a basement, that’s perfect. If not, you can store it in the back of a cabinet or closet on your first floor.
I’ve stored paint this way and had it last 5 years, which is about twice as long as it should have. One last tip: get in the habit of writing the date the paint was first opened on the can. This way you can easily track the paint’s “shelf life”. Who knows, maybe you’ll find out you can store leftover paint a lot longer than anyone thought possible!