No matter how careful we are, there comes a time when even a crisp, clean paint job will need a touch up. Each container of paint is custom mixed. Even if you have the formula, there are no guarantees the color of a new can will be an exact match to your previously painted surfaces. The best insurance of a perfect match during the paint selection process, especially important for custom faux finish paint jobs, is to save the leftover product.

Here are some simple steps that you can take to extend the shelf life of your remaining oil based paint or any type of paint, beginning the moment you open the can.  

Before you start:

• Do all preparations of your work area before opening the can. This includes assembling your tools, taping and placing drop cloths.

• Don't stir the paint if you're using it within 24 hours of purchase. Reputable paint stores do a good job of mixing the product when you buy it.  

• Remove the lid carefully with a paint can opener (which most paint stores will provide free of charge). Attempting to pry the can open with a screwdriver or other tool may distort the lid, making it difficult to create a good seal when you're done.

During your project:

• Minimize the number of times you open the can. Do not leave it open while you are painting. Exposure to air is what makes paint harden. 

• If you need to stir the paint, do it gently so additional air is not introduced into the product. When finished, remove the stir stick and close the lid.

• Pour paint into a small container or roller pan. Clean the well (indentation around the top of the can) and replace the lid. Even covering the can with a shower cap while you're painting will help keep it fresh.

• Never dip your tool directly into the can. The brush or roller will pick up dust and lint from the wall, which will be transferred back into the fresh paint.

• In the event your latex paint is too thick, take out the amount you need and place it in a separate container before diluting. If you add water directly into the can, the remaining paint will spoil prematurely or even form mold. Discard any diluted paint.

When you are done:

• Before closing the can, clean the lid and the well of excess paint to make sure there will be a good seal.

• Place a piece of plastic wrap inside touching the top of the paint before replacing the lid.  This will exclude air and prevent a surface film from forming.

• If the can is less than half full, consider transferring the remaining amount into a smaller paint container (available at most paint and hardware stores) so there will be less air inside. Or use any type of container that will maintain a tight seal -- like a Mason jar.

• Seal your paint can tightly. It's best to tap the lid shut with a rubber mallet to tap the lid shut. If using a hammer, place a piece of wood on the top to avoid distorting the lid. 

• If your paint is in a plastic container, clean the threads along the sides and inside of the lid. Then coat them with a small amount of petroleum jelly to create a good seal.

• Label the lid of each can with the formula name and number. Try not to allow paint to drip over the sticker the paint store provided. Also include the date of purchase and the room where you used it. For quick reference, put a dime-sized drop of the actual paint on the top. These tips eliminate the need to open the can any more than necessary.

Where to store paint:

• Store leftover paint in a climate-controlled environment. Freezing renders paint products unusable. Likewise, excessive heat (next to a water heater or furnace) will make it react with the excess air in the container and cause it to thicken. 

• Do not leave paint cans on a concrete, stone or tile floor. Moisture will cause the can to rust over time and will distort the color.

I have found that the higher the paint quality, the longer it will last on the shelf. Following these guidelines or the advice from your local painters can mean I just need to do a simple touch up instead of having to completely repaint a whole surface. I always give a sigh of relief on opening a can of paint years later and finding that it is still usable for another eco-friendly house paint project.

Kass Wilson writes for Networx.com.

Updated February 20, 2018.