David Savastano, Contributing Editor02.07.23
When discussing the life of paint and coatings, there are terms that seem to be used interchangeably. For example, shelf life, pot life and working life are used in describing the life expectancy of a paint of coating, but they don’t mean the same things. Let’s take a look at what each of these terms mean:
So how long can a can of paint last on the shelf? That depends on the type of paint, and of course whether the can has been opened and whether it is being stored properly. For example, I’ve seen numerous estimates placing water-based latex paints and acrylic paints at anywhere from two to 10 years, and oil-based paints from two to 15 years.
Why is this? Latex paints are water-based and use fewer preservatives, which has an impact on shelf life. Acrylic paint is chemical-based and use more preservatives. Oil-based paints are also typically the longest lasting once they are opened.
When you store opened paint, the most important factor is that you seal the can well, as air will cause bacteria to spoil the paint. Use a rubber hammer or put a board on top, hammering along the can’s edges. Also, keep the paint in an area where it won’t freeze or get too hot. If you only have a small amount left, you can pour it into a smaller container. Home Depot recommends either a wide-mouth glass or plastic jar with a screw-top lid, or a clean, dry pint or quart size paint can.
Above all, please remember to write information on the lid or container, like where you used the paint, the date you used it and what color and brand it is.
Dulux Protective Coatings offers this explanation:
“Pot Life” is a term used for two-pack (or multi-pack) coatings that cure through a chemical reaction, such as epoxies and most polyurethanes. These systems consist of a base component (often called the “Part A”) and a catalyst or hardener component (often called the “Part B”). When these components are mixed together, a chemical reaction starts that leads to the curing of the paint.
“Pot life is the time from mixing the two packs together to the point at which the mixed paint is no longer useable. It is also known as the working time or useable life.”
Once the chemical reaction occurs, heat is generated, and solvent and water evaporate out. As the reaction continues, the paint and coating’s viscosity increases, and it eventually becomes too thick to apply.
Shelf Life
Shelf life is, quite simply, how long an item can remain on a shelf and still be usable. For paint and coatings, it means how long a can of paint can last on your shelf and still be used to paint or do touch-ups. Home painters typically have leftover paint, and that can separate or harden over time. Stirring the paint with the traditional wooden stirrer can re-integrate the paint if it has separated, but if it has hardened, that’s beyond fixing.So how long can a can of paint last on the shelf? That depends on the type of paint, and of course whether the can has been opened and whether it is being stored properly. For example, I’ve seen numerous estimates placing water-based latex paints and acrylic paints at anywhere from two to 10 years, and oil-based paints from two to 15 years.
Why is this? Latex paints are water-based and use fewer preservatives, which has an impact on shelf life. Acrylic paint is chemical-based and use more preservatives. Oil-based paints are also typically the longest lasting once they are opened.
When you store opened paint, the most important factor is that you seal the can well, as air will cause bacteria to spoil the paint. Use a rubber hammer or put a board on top, hammering along the can’s edges. Also, keep the paint in an area where it won’t freeze or get too hot. If you only have a small amount left, you can pour it into a smaller container. Home Depot recommends either a wide-mouth glass or plastic jar with a screw-top lid, or a clean, dry pint or quart size paint can.
Above all, please remember to write information on the lid or container, like where you used the paint, the date you used it and what color and brand it is.
Pot Life
Pot life tells you how long multiple-part paint and coating can be applied to a surface after it has been mixed. Technically, it is how long the paint’s viscosity takes to double and the paint and coatings become too thick to apply. If the paint and coatings has been poorly mixed or has been left unused for a while before the project is started, then the pot life is off.Dulux Protective Coatings offers this explanation:
“Pot Life” is a term used for two-pack (or multi-pack) coatings that cure through a chemical reaction, such as epoxies and most polyurethanes. These systems consist of a base component (often called the “Part A”) and a catalyst or hardener component (often called the “Part B”). When these components are mixed together, a chemical reaction starts that leads to the curing of the paint.
“Pot life is the time from mixing the two packs together to the point at which the mixed paint is no longer useable. It is also known as the working time or useable life.”
Once the chemical reaction occurs, heat is generated, and solvent and water evaporate out. As the reaction continues, the paint and coating’s viscosity increases, and it eventually becomes too thick to apply.
