One of the best things about working with acrylic paints is their lack of smell. No irritating, harsh, chemical odors to overwhelm and suffocate your senses. Only those with extremely sensitive noses might be able to notice the slight scent.
Other than that, acrylic paint barely has any detectable odor and is considered safe paint. You can use them indoors for hours at a time without any problems. That is, until one day, you open a tube of acrylic and can barely tolerate its strong odor.
So, Why Does Acrylic Paint Smell Bad? It may do this even when no organic solvents are used like with oil paint, which can be confusing. There can be a few reasons for that, and this article will discuss them in detail. We will also talk about their toxicity 
and things you can do to get rid of the smell.
Table of Contents
Why Does Acrylic Paint Smell Bad?
Like most objects, acrylic paints have a limited shelf life and can go bad when it ends. Extreme temperatures can also ruin the consistency of your art products. You will easily realize when the paint has gone bad because the most prominent sign of a paint past its expiry date is its strong and unpleasant odor.
If you store acrylic paint properly, it can last for years. On average, properly stored opened acrylic art materials can be used for 3 to 5 years at a time, while an unopened tube can remain in optimal conditions for over ten years.
However, most acrylic paints can go bad even before their expiry date. This might have happened because you accidentally introduced contaminants into your paint during use which led to the growth of mold. The smell feels sour and aged.
You can transfer these bacteria in one of two ways: either by using regular tap water as a diluter or through your brushes. Regular tap water contains a lot of microbes which then fester within the container when stored for an extended period.
On the other hand, brush bristles may also contain bacteria that get transmitted within the containers.
How to Limit Contaminating Your Acrylic Paints?
If you are worried about paints going bad too fast, there are a few practices you can adopt to avoid it.
Use Distilled Water
Distilled water has a low mineral content after most of its contaminants and impurities are extracted. So, you can use it to dilute the paint and store it in a separate container for it to last longer. So, even if the diluted paint goes bad somehow, you will not waste the rest of the tube.
Besides, using distilled water is not only better for the health of the paint but the quality as well. Tap water can sometimes react with acrylic paint to create a runnier consistency, which can affect the way you paint.
Clean Your Brushes
Molds grow on brushes, no matter what measures you take to clean them. It can then alter the color of your paint, transfer to your paint tubes, acrylic medium, or your paintings and then sprout on them.
Brushes must be cleaned promptly at the end of each session. Do not let the paint dry, as it can ruin the quality of your bristles. Using just soap and water is enough to easily clean off acrylic paint. You can dip them lightly in ammonia or other mild cleaning agents to kill off any bacteria.
Keep Track of Dates
You can note down or mark the paints’ purchase date on the back of your acrylic colors using a marker. Paint with the older paints first so that you use them up before they pass their expiry dates.
You can also buy a limited palette so that you use them faster and not let it sit for an extended period. Buying a set with 6 colors instead of 24 will cause you to replace them more often, but it also decreases the possibility of your paints going bad.
You can buy smaller tubes or sample kits in common colors if you do not paint very often.
Does Acrylic Paint Have a Smell in General?
Preservatives are added to acrylic mediums to increase their shelf-life. These preservatives have a slight smell that is barely noticeable by most people. You can go on working with these paints for hours without even noticing them.
Ammonia is a popular choice of preservative by most paint manufacturers. It is added in small quantities, barely close to the amount used in cleaning agents. Sometimes, acrylic paints can contain formaldehyde instead.
Fortunately, the smell of preservatives is not too strong and can be ignored. But if you have any kind of allergies or are sensitive to such a painting medium, it would be better to contact a representative of the company.
You can easily avoid triggering unnecessary allergic reactions and ruining what is supposed to be a fun painting session.
What Should I Do with My Old Paints?
Unfortunately, if your paint has developed a pungent smell like that of soured milk, you have no other choice but to throw it out. However, not all old paints are unsalvageable.
These are some common problems that you might face with old paints:
Dried Paint
Paints stored over long periods can dry up and become stiff, thick, and lumpy, especially if stored at an extreme temperature. It becomes very difficult to get dried paints out of the tube.
If this happens, you can add water and mix it in to change the fluid consistency. Since acrylic paint is water-based, the hardened pigments soften with water. Start with a small amount and add in more as you need to not compromise the coverage and color.
If the paint is rock hard, you can use a clear acrylic base or paint thinner instead of water. You can also try using water-based solvents.
Separated Paint
Acrylics consist of a binder mixed with pigment. Sometimes, because of a manufacturing defect or cheap quality, these two components get separated. When this happens, you will notice an almost-clear liquid puddled around thick paint when squeezed out of the tube.
Fixing this problem is quite easy. Just take a palette knife and mix the pigments and binders in a swirling motion on your preferred choice of palette.
Fast Drying
Natural oil-based paints are prone to drying fast. But sometimes, the paint dries just as soon as you squeeze them out of tubes and before you put them on the canvas.
You can turn off any fans you have running or close windows to block out any drafts or airflow. If the wind is too strong outside where you are painting, you can shift inside.
Moreover, you can keep a spray bottle on hand to mist down the paint and canvas while working. Squeeze out the paint in small amounts first and then more as you go.
Is Acrylic Paint Toxic?
Acrylic paint is relatively safer than oil paints. Since it does not require an organic solvent, it does not off-gas much volatile organic compounds. They are water-based, which usually entails non-toxicity. But sometimes, they may contain carcinogenic toxic chemicals which can release harmful fumes when dried.
However, this problem is most present when airbrushing or spraying. If you are not wearing the proper respiratory gear, you can irritate your nose, lungs, and throat by inhaling them.
Therefore, different materials like leads are banned from being used in paints. Although, other heavy metals, such as cadmium, cobalt, manganese, are still used, which can be highly toxic when exposed to them.
If you want to use a non-toxic version, look for products labeled as non-toxic. Read the ingredients label to know exactly what substance is being used so that you are safe while painting.
Even then, the artist should avoid exposure and not consume large amounts as it can lead to severe digestive issues, including vomiting. Increasing ventilation can also help get rid of the odor.
Final Words
Painting with acrylics is the least hassling and bothersome. They are water-based, dry fast, do not make much of a mess, and the best part, they do not have an overwhelming smell.
But sometimes, due to mold growth, acrylic paint may develop a particularly nasty smell that can be too strong to ignore. And this smell is a clear tell-tale sign that your acrylic paint has gone bad.
Well, if you were wondering why my acrylic paints smell bad, there is your answer. Unfortunately, though, you cannot do much about it. Acrylics are widely considered by every artist to be perfectly safe, so you do not have to worry much about their exposure or their ill effects.