Why Does Polyurethane Foam Turn Yellow?

The polyurethane foam market is an ever-growing one of over $62 billion, and experts predict growth to $112 billion by 2028. The reason for this growth is the increase in residential construction in the US, where homeowners use polyurethane foam. However, after a while, some part of the foam starts to change color to yellow, causing you to wonder if it’s safe.

Polyurethane foam turns yellow because of a chemical reaction that occurs while they age, which occurs when the amine in the polyurethane mixes with oxygen under UV light to form yellow quinone. The reaction occurs in batches and spreads over time, depending on the sunlight exposure.

This article will guide you on preventing your polyurethane from turning yellow and what you can do when you notice the yellow shade. Let’s get started!

Why Does Polyurethane Foam Turn Yellow?

How Do You Keep Polyurethane From Turning Yellow?

As I have mentioned, polyurethane turning yellow is usually a matter of age and UV light exposure. Also, it’s essential to note that having a yellow polyurethane foam will not affect its performance.

However, the idea of having your foam react is never a good one, so here are some preventive steps to stop polyurethane from yellowing:

Purchase a Trusted Polyurethane Foam

The first step to preventing your polyurethane foam from turning yellow is buying from the correct source. But before you purchase the foam, you must determine what you need it for.

You can buy polyurethane foam for two things majorly: for insulation and as a mattress.

Polyurethane Foam for Insulation

Spray polyurethane foam is a popular type in the market, with a predicted market cap of over $2 billion by 2028. The polyurethane foam is usually outside as insulation, so you may need to buy a UV-resistant polyurethane or add a UV-resistant sealant. I recommend the Minwax Water-Base Wipe-On Polyurethane on Amazon.com because it doesn’t alter the design of the polyurethane while giving it optimal protection.You may also use spray polyurethane to protect wood from termites. [Does Polyurethane Protect Wood From Termites?]

Polyurethane Foam as a Mattress

Polyurethane, mostly oil-based, forms many of the great beds across the globe today. If it’s possible to get water-based polyurethane foam for your mattress, please do. The chemistry behind the formation of water-based polyurethane is a combination of hydroxyl groups, a moiety, and isocyanate. None of these compounds form quinone, which causes the yellow color change.

The oil-based polyurethane is a more common type of foam, and the yellow shade doesn’t harm if you buy a good-quality foam. If you’re purchasing a polyurethane mattress, the best way to ensure safety is to choose the bed certified by Certipur US.

Certipur US is a non-profit organization that ensures that your mattress production process is safe for you. Some of the advantages that this certification assures you of include the following: 

  • There’s no presence of heavy metals like mercury and lead in the construction process. 
  • Your mattress contains zero ozone depleters.
  • It also has zero flame retardants.

Aside from purchasing a mattress certified by Centrpur US, it can help if you understand the materials used to make the foam before buying it. Most manufacturers add antioxidants to the production process, which can have good and bad effects.

Prevent Sunlight Exposure 

The chemical reaction that gives off the yellow shade on polyurethane foam requires UV light to take place quickly. Therefore, as much as possible, try to keep the foam away from the sun as much as you can. 

The mattress can accumulate dirt over time, giving off rotten smells and requiring air drying. However, if you must air dry it, try to avoid directly putting it under the sun. Apart from fostering the reaction that will give off the yellow color, it can also damage your foam. 

There are two ways to air dry outside and avoid the sun simultaneously; they include:

  • Spread it under a shade. You only need natural air for the mattress to dry appropriately. So putting it outside your home under a covered point is a great way to dry it without the danger of the sun. 
  • Use a UV-resistant net cover. If you can’t find a good shade for the item, you can get a UV-resistant net to cover the mattress while you put it under the sun. I recommend using the EVETTO 70% Sunblock Shade Cloth Net Black (available on Amazon.com) for this purpose. The cover is large enough to envelop your bed completely and block up to 70% of the sun’s rays. 

Clean the Polyurethane Foam Regularly

It’s effortless to neglect the need to wash your mattress from time to time. However, the mattress is home to different types of dirt and mess from you laying on the foam, including:

  • Sweat: When you come home tired from a tough day’s work, the most likely place you will land is your mattress to take a little nap before freshening up. However, you pass a lot of sweat and body oil to the foam. This sweat may not cause your polyurethane foam to be yellow, but they often come with a bad smell. 
  • Food and mold growth: If you’re fond of eating on your mattress, some food crumbs may fall on the bed, causing some dirt. You pick these crumbs from the bed, forgetting that most meals have oily ingredients that dirty the surface. After a while, the components will build up with other dirt to form mold stains on the mattress. 
  • Urine: If you have a toddler, there’s a high chance that they stain the bed with urine. Air drying the bed will dry the urine, but it doesn’t make the mattress clean. Urine stains on your polyurethane form can also be yellow because of ammonia. 

There are different ways to clean your mattress whenever there are stains. Some of the methods include:

Use Hydrogen Peroxide

Hydrogen peroxide is a chemical in many laundry and dyeing products, and you can easily buy it on Amazon. When you have your hydrogen peroxide chemical: 

  1. Apply it to the stained area and scrub it with a soft sponge.
  2. Use a damp cloth to clean the washed area.
  3. Air dry the mattress. 

Clean Using a Vacuum

Using a vacuum cleaner is a straightforward way to clean the mattress, but it would be best if you have a steam-based vacuum cleaner. All you have to do is clean the bed thoroughly with the mattress on the floor. You must air-dry the mattress using a water or steam-based vacuum cleaner. It’s always better to clean both sides, so you can switch it when it’s dirty. 

Use Detergent

As I’ve mentioned above, most laundry detergents have hydrogen peroxide chemicals to take care of the stains. I recommend the ECOS Hypoallergenic Laundry Detergent (available on Amazon.com) for this purpose. This detergent contains plant-based constituents only and has certification with the Environmental Protection Agency, so your mattress is safe.

Use Local Cleaning Materials

Some household items have multiple purposes and can form excellent cleaning solutions in the home. Examples of these materials include vinegar and baking soda, amongst others.

You can watch the YouTube video below to get a practical idea of how to use these household items:


The cleaning solutions mentioned above can still work on your polyurethane foam when it’s turning yellow in its early stages. You can use it alongside another cleaning method if one doesn’t clean it properly. 

However, the preventive method is the best way to ensure there are no yellow stains on your polyurethane foam. Clean the stain immediately with either the vacuum (if there’s no oil) and baking soda or soap if there is an oil stain. Remember to air dry the spot you cleaned, as laying on the wet portions can cause more dirt. 

Use a Great Foam Cover

If you have your polyurethane foam as insulation outside your home or inside, covering it is an excellent preventive action against the yellow color.

When thinking of a cover for the polyurethane foam, some of the factors include the following: 

  • Waterproof quality: The bed cover needs to have some resistance against water, especially if you have polyurethane foam as a mattress. The waterproof quality will ensure that wet stains don’t touch the bed. These wet stains are usually the main culprits, so you’ll stop at least 80% of the dirt on the mattress. 
  • UV resistance: This feature is vital if you have polyurethane foam outside your home or close to the windows where sunlight can creep in. The cover will block the sun’s rays, slowing the reaction and causing the yellow color. 
  • Size: If you purchase a bed cover, ensure it can cover the polyurethane mattress entirely for an effective solution. 


You can’t completely prevent a polyurethane foam from getting the yellow stain, as oxidation is a natural process that occurs.You can slow the reaction by limiting the amount of sunlight and stains that get to the bed. 

The best way to keep your polyurethane mattress free of yellow stains is through cleaning: 

  • Preventive cleaning: This type is the routine and regular cleaning of the polyurethane foam with or without visible stains or yellow signs. 

Reactive cleaning: This type is the one that occurs when you’re cleaning the polyurethane foam after noticing the stains or yellow color.

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