How Long Does Paint Last

How Long Does Paint Last?

A good painting stands the test of time, but what really makes it last? The quality of the paint itself.

From artists’ palettes to contractors’ paint rollers, paint has long served both creative and practical functions. To make it serve your purposes for as long as possible, it is worth knowing the answer to the question: how long does paint last?

First you need to know what type of paint you have.

​To determine how long paint lasts, first you need to know the type you’re dealing with. The type is a primary factor for various reasons, not just for determining how long the surface coating will last. You’ll also want to know the type because different kinds of paint are appropriate for various projects.

Paint was once made with linseed oil, but according to Dr. Rebecca Ploeger and Dr. Oscar Chiantore, the outbreak of World War II made linseed oil scarce. In its place, alkyd paints, also called oil-based surface coating, developed and changed the industry.

According to Encyclopaedia Brittanica alkyd paints contain alkyd resin, which is as an oil-modified polymer.​

As a contractor, I frequently use oil-based products for commercial and residential projects. They have great durability and long-lasting effects. But there are other, high-quality and long-lasting paints on the market.

Latex, or water-based surface coatings, also last for an extensive period, and they are excellent for DIY projects, interiors, exteriors, wood furniture, you name it. Latex also comes in a variety of finishes and dries faster than oil-based surface coating.​

​If you find a can of leftover surface coating in your home with the label worn off, you can find out which type was used on the original job. This is a simple latex vs oil-based quality check. Check out the video below from TheMuskokaPainter to see this oil-based vs latex check in action.

In addition to oil and latex, other types of paint include milk-based and chalk, both of which have become popular because of their unique finishes.

Next, you have to determine the storage conditions.​

​Knowing the type of paint can give you a rough estimate but you also must know a thing or two about the storage conditions. So, to determine the true shelf-life, the real question to ask is: how long does paint last in a bucket?

When stored in a cool, dark place and sealed airtight, oil-based paints can last up to 15 years. The long-lasting performance of alkyd paints means you can keep a can of leftover paint for touch-ups for many years.

Latex surface coatings can have a similarly long shelf life of 10 years, as long as the cans are not frozen. Chalk paint also has a longer shelf life. According to Annie Sloan, the inventor of chalk paint, the shelf life of chalk paint is several years.​

​The only one that doesn’t have an extensive shelf life is milk surface coating. Since it is made with milk, it only has a shelf life of 2 to 4 weeks. This isn’t too bad though since this type looks best when applied freshly after mixing.

​There are ways to tell if paint has gone bad.

​You know the answer to the question of how long can you keep paint before it goes bad. But sometimes the storage conditions of a bucket of surface coating might be unknown to us.

This can be frustrating if you’ve ever moved into a place and received buckets of the original surface coating that was used on the house but you don’t know what conditions it was stored in. You don’t want to use bad or rotten paint and end up ruining the walls and wasting your time.

So, how can you tell if paint is bad? There are a few signs that will tell you if and how the surface coating has spoiled.

Sometimes you can tell by the smell. Spoiled surface coating might smell sour or rotten. The stench comes from small mold or mildew spores that were trapped inside the can.

Paint can also grow mold, which is visible on the surface of the paint itself. The mold can appear in various colors, including black, green, or gray, and it might appear fuzzy or chunky. Mold festers when the bucket is stored in warm, damp environments.

The external appearance of the can might also indicate whether the paint has gone bad. According to Consumer Reports, latex paints that are spoiled can make the bucket itself inflate. The swelling is caused by built-up pressure from gas-releasing microorganisms in the can.

Man-painting-wooden-door

​How do you check to see if paint has gone bad?

​If there aren’t any signs of foul smell or discoloration but you still suspect the surface coating has gone bad, you can also perform a manual check. A quality check is a good idea for safety reasons because you want to avoid painting your walls in anything that has mold.

When you open the can, you might notice some separation of the paint components. This is a natural separation process and does not mean the surface coating is bad.

To do a manual check, all you need is a mixing stick. Mix the paint, making sure to scrape the bottom of the bucket.If the surface coating is good, then the separated components should mix back together.

If it has gone bad, then you may feel some hardened material at the bottom of the bucket. When mixing doesn’t work, you can assume the paint has spoiled.

​Make Your Paint Last

​If you end up with leftover paint, don’t waste it by throwing it out. You’ll probably want to keep it on hand in case you need to touch up any areas later.

To make your paint last, follow proper storing methods. According to the EPA, hazardous products should be stored in the original container with the label left intact. Placing a sheet of plastic wrap over the top and then firmly closing the lid should make for an airtight seal.

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