How can you tell if paint is bad

How Can You Tell If Paint Is Bad?

Are you planning on painting your home with leftover paint? If you are, you must find out whether your paint is safe for painting.

That’s why I put this article together – to tell you everything you need to know when you need to determine if paint has gone bad.

In this article, I’ll talk about how long paint lasts and how you determine if your paint has gone bad. Not only that, but I will also tell you what happens when bad paint is used for interior painting and if it’s harmful when you do it.

Let’s dive in!

Expired paint inside paint tin

What Does Expired Paint Look Like?

If you decided to pour leftover paint back into the can some time ago, you need to be able to tell whether the paint has gone bad when you open it.

It’s relatively easy to tell if you have expired paint on your hands.

Here are the signs you need to look out for in order to tell if your paint is expired:

Smell: an unpleasant smell is one of the first signs that it is time to discard your old paint. The foul odour comes from bacterial growth, which spreads to your walls if you apply the paint. So, if you notice a rancid smell, you must dispose of the paint.

Consistency: paint develops a jelly-like and lumpy texture when it expires. So, when you open your paint tins, mix them with a stirring stick. If you find lumps in your paint, it’s not useable, and you need to get rid of it.

Separation: when paint goes past its shelf life, it begins to separate – with the heaviest components sinking to the bottom of the paint cans and the lightest parts rising to the top. So if your leftover paint looks like it’s separated, you should discard it straight away.

Discolouration: paint begins to change colour when it expires. So if your leftover tins of paint have a different colour than expected, it’s best to dispose of them straight away!

Tins of paint that have gone bad

How Long Is Paint Good For After Opened?

How long your paint will last once you have opened your tins depends on the paint type and how it is stored.

Let’s take a look at that in more detail:

How Long Does Water-Based Paint Last Once Opened?

Water-based paints usually last 1-2 years once after being opened, as long as it is stored correctly.

If you don’t store your paint in the proper conditions, it will thicken and separate over time. Also, it will begin developing mould or mildew.

How Long Does Oil-Based Paint Last Once Opened?

Oil-based paint will be fine 2-5 years after opening your paint cans.

However, how long you can safely paint with your leftover paint will depend on how you store it after opening. I’ll talk about how the storage conditions of the paint cans determine how long they will last in the section after the next.

Dripping tin of paint with a stiring stick inside it

Does Paint Expire If Not Opened?

Even if you keep your paint sealed, it will eventually expire. The lifespan of your paint will depend on the paint type and how it’s stored.

How Long Does Unopened Paint Last?

The time that your paint will last depends on the type of paint you have – here’s a guideline for each type of paint:
• Water-based (or latex) paint: lasts 8-10 years
• Oil-based paint: lasts 12-15 years
• Acrylic paint: lasts 5-10 years
• Milk paint: lasts 1-2 years
• Chalk paint: lasts 3-5 years
• Mixed paint: lasts 3-5 years

What Happens If You Use Bad Paint?

Avoid using paint that has gone bad at all costs.

If you use old paint that has gone bad, you’ll run into these issues:

  • Durability: Expired paint is not as durable as fresh paint. So, when you apply the old paint to your surface, it will be more prone to chipping, cracking, and peeling.
  • Colour change: Over time, the pigment in the paint will break down, resulting in a shift in the appearance of the paint colour.
  • Texture: Bad paint tends to become lumpy, and when it’s applied to a surface, it will be hard to get a smooth finish.
  • It smells: When paint starts to go bad, bacteria grow, creating a sour smell. Painting with expired paint will result in these awful smells transferring to your interior.

As you can see, it’s never a good idea to use rotten paint as you will set yourself up for various problems and a low-quality finish.

So, to avoid having to start your DIY painting project over again, visit your local paint shop and purchase some new paint. Or ask your local painter and decorator to pick some up for you. And that’s exactly what happened when we were completing a paint job for a client of ours in Chiswick.

Dangers Of Using Old Paint

Using old paint won’t just result in a poor-quality decorating finish. In fact, if paint has expired and you use it, it can be harmful to your health.

Here’s why:

  • The VOCs in the paint products will begin to degrade over time. When you apply the paint to your wall, you put yourself at risk of inhaling these chemicals. If inhaled, it can lead to respiratory irritation, allergic reactions, and other health problems.
  • Paint that is old is more likely to develop mould or mildew – especially when paint is exposed to moisture or improperly stored. Exposure to mould or mildew can worsen existing asthma conditions or cause new respiratory conditions.

Should I Save My Old Paint?

It’s always a good idea to keep your old paints. Keeping your old paint can save you money and time if you need to touch up any already painted areas of your house.

Storing your paint in the right conditions is the best way to prolong how long it lasts.

It’s not only necessary to store your paint correctly, you must give the paint a stir as you would with any new product. Properly mixing the paint before using it will bring the best results.

How To Store Your Paint Properly

In order to keep your paints for the longest time possible, you need to store your paints properly.

Here’s what you need to be aware of when storing your paint:

  • Temperature: You need to store your paint in cool and dry conditions. To make the paint last as long as possible, you must avoid freezing temperatures, as this will ruin the consistency and effectiveness of the paint.
  • Light: You need to keep your paint away from the sun as UV exposure will ruin the paint and change its colour.
  • Keep it closed: You need to ensure the seal of the paint remains intact to prevent air from getting into the paint and drying it out.