Polyurethane is used to keep wood from dents and scratches and protect it from water damage. It is one of the best wood finishing products that can apply to any furniture to protect from environmental elements.
Usually, I use oil-based polyurethane for most of my woodworking projects. But recently an expert in wood finishing suggest water-based polyurethane instead of oil-based one since it has no odor and dries faster.
But I was curious about using water-based polyurethane over oil-based since during the time I used oil-based polyurethane I had to fix the yellowing of oil-based polyurethane from time to time at least once per year.
So, I did some research to find out how oil-based and water-based ones differ when it comes to yellowing over time. I’ll share everything I gathered with practical examples.
Let’s discuss, Does water based polyurethane yellow?
Water based polyurethane does not yellow over time since it does not oxidize when exposed to UV light. Water-based polyurethane is clear and holds the natural color of the wood without yellowing. Use quality water based polyurethane products that are formulated well to avoid a yellowing finish.
But there are a lot more tips to get into this.
So, in this post, we’re diving deep into does water based polyurethane yellow, what makes polyurethane yellow, what are the best non-yellowing polyurethane and how to fix yellowed polyurethane, and more.
Furthermore, I’ll answer some frequently asked questions as well.
Let’s get started!
Why Water-Based Polyurethane Does Not Yellow?
Water-based polyurethane does not yellow because the chemical components of water-based polyurethane do not oxidize under exposure to UV rays in direct sunlight.
Unlike oil-based polyurethane, water-based polyurethane does not change its color over time.
Water-based polyurethane contains less VOC, paint chemicals, and solvents than oil-based polyurethane which makes it less likely to yellow over time.
The natural color of the wood remains the same with water-based polyurethane and you’ll be able to keep the same color for so long with proper maintenance with no discoloration.
Oil-based polyurethane turns yellow because when it cures oxidation reaction happens.
Due to the oxidation reaction oil-based polyurethane turns yellow and the rate of yellowing increases over time with exposure to direct sunlight.
Some people love the warm color oil-based polyurethane provides with yellowing. But some don’t.
If you love the natural color of your wood furniture, better to apply water-based polyurethane since it doesn’t change the color under any circumstance.
But you should use quality water-based polyurethane products for finishing the wood. Because some cheap low-quality water-based polyurethane finishes tend to yellow slightly over time.
Always go for quality products when wood finishing since, using low-quality product decrease the lifetime of your furniture.
What Makes Polyurethane Yellow?
Water-based polyurethane does not yellow. Oil-based polyurethane is yellow over time due to oxidation.
There’s a molecule known as chromophores in the oil-based polyurethane that cause the yellow color on polyurethane.
Chromophores activate when they stay in dark. They will break down under light and sunlight conditions and fade the yellow color back to the original color of the wood.
This is surprising since polyurethane turns more yellow when it stays in the dark. But because of the UV rays it accelerates the oxidation process and turns polyurethane yellow.
UV light makes polyurethane yellow as it cures over time.
When the oil-based polyurethane cures over time its chemical components go through an oxidation reaction to form a polymerized coating over the wood.
This polymerized layer is what protects wood from outdoor elements like moisture, humidity, water damage, rotting, insect attacks, and more.
This oxidation reaction is triggered by antioxidants. UV light in direct sunlight accelerates the oxidation reaction of oil-based polyurethane.
As a result, the polymer will oxidize and turns a yellow color.
As a summary, here’re some possible reasons that make polyurethane yellow,
- Ultraviolet light
- High-temperature levels
- Reaction with nitrogen oxide gases that occur from motor emissions
- Due to butylated hydroxytoluene as an antioxidant
Among the above reasons, UV light is the cause of the yellowing of polyurethane.
Let’s identify the best non-yellowing polyurethane types to stay away from yellowing forever.
What Is The Best Non-Yellowing Polyurethane?
Water-based polyurethane is the best non-yellowing polyurethane. Even the best commercial products of Oil-based polyurethane are yellow over time no matter what you do.
It’s only a matter of time. But quality oil-based polyurethane takes longer to yellow than cheap, low-quality ones. However, one day all the oil-based polyurethane coats will turn yellow.
Surprisingly some low-quality cheap water-based polyurethane products turn yellow. That’s because of the poor-quality chemical compositions.
Therefore, even though you have selected water-based polyurethane to stay away from yellowing, it still follows you like a nightmare if you go with a low-quality product.
Some quality water-based polyurethane products don’t yellow over time.
You just have to clean the surface at least once per few months to remove dust and debris to get it back to its original color. The natural clear color will remain constant over time.
Here’re some of the best non-yellowing polyurethane products,
- Minwax Polycrylic
- Varathane Ultimate Water-Based Polyurethane
- Bona Traffic HD Polyurethane
- StreetShoe Polyurethane
- Loba WS 2K Supra
All the above water-based polyurethane products do not yellow over time. they are easy to apply and dry faster than oil-based polyurethane products.
Reapply water-based polyurethane on wooden surfaces at least once per two years to keep the wood protected for so long with excellent durability.
Polyurethane Yellowing Fix
You can fix the yellowing of polyurethane with some simple methods. But there’s no quick and permanent fix since oil-based polyurethane does yellow over time and nothing can stop it from happening.
Here’re some proven fixes for the yellowing of polyurethane,
- Rub the yellowed polyurethane areas with mineral spirits using a rag
- Use artificial light to fade the yellow tint of polyurethane by deactivating the chromophores
- Strip the polyurethane finish and start over with a quality water-based polyurethane product
Using the above methods, you’ll be able to fix yellowed polyurethane areas.
If none of the first two methods worked, unfortunately, you’ll have to strip down the existing polyurethane finish and start over with a non-yellowing water-based finish.
That’s it, folks! Use water-based polyurethane made with a quality formula by a branded manufacturer to keep your polyurethane-coated furniture and woodwork from yellowing.
Let’s answer some frequently asked questions.
Does All Polyurethane Turn Yellow?
No, not all polyurethane turns yellow. Oil-based polyurethane does yellow and water-based polyurethane does not.
Water based polyurethane contains fewer VOC compounds, paint chemicals, and other chemicals which makes it less likely to yellow over time.
Oil-based polyurethane contains chromophores which are sensitive to light and cause yellowing.
UV light accelerates the yellowing process of polyurethane which makes the coat yellow upon curing over time.
You can fix yellowed polyurethane by rubbing it with mineral spirits, fading the yellow tint away using artificial light, or scraping the existing finish and starting over with a new coat of water-based polyurethane.
Always use quality products even when finishing with water-based polyurethane since low-quality, cheap water-based polyurethane products are also may slightly yellow over time due to poor chemical compositions.
How To Keep Polyurethane From Yellowing?
You can keep polyurethane from yellowing by preventing the exposure of polyurethane-coated furniture and woodwork to the UV light, and apply thin coats of polyurethane and sand between each coat of polyurethane during the application.
UV light accelerates the yellowing process upon the curing process of polyurethane.
Or you can place your furniture and woodwork inside of the house or use UV filters for windows to prevent UV light from coming inside.
However, your main mission is stopping the UV light from hitting the wood surface.
Apart from that you can keep polyurethane from yellowing by preventing it from happening mistakes during the application of polyurethane.
Try to avoid and fix polyurethane mistakes when applying.
Apply thin coats of polyurethane all over the surface evenly without forming a blotchy or splotchy surface.
Make sure to sand lightly between coats of polyurethane to improve the adhesions and smoothness between the surface.
Following the methods above, you’ll be able to keep polyurethane from yellowing.
How Long Does Water Based Polyurethane Last?
Water-based polyurethane lasts for around 10 years. Low-quality water-based polyurethane lasts for around 5 to 6 years.
But this can vary upon the type of application and where you place the wood furniture.
If it is outdoor furniture, water-based polyurethane won’t last 10 years since the furniture will get frequent impacts from weather elements such as UV light, moisture, water damage, and more.
Plus, you need to maintain the furniture properly by removing dust, debris, and grease on the polyurethane coat to keep it as fresh as new and to increase its durability.
As a woodworker, I highly recommend you apply water-based polyurethane at eats once per two years to keep the furniture protected for so long and stop polyurethane coats from fading away.
As soon as the polyurethane coat is faded, the furniture will expose to the outside and moisture will find a way to penetrate the wood and start wood rot.
Can You Paint Over Yellowed Polyurethane?
Yes, you can paint over yellowed polyurethane. First, you need to do a light sanding and remove the glossy yellowed layer on the polyurethane finish.
Then apply any color of paint you like over the polyurethane surface.
Finally, apply a stain-blocking primer like shellac on wood to seal the surface.
Removing the yellow color polyurethane layer is a must before painting since the yellow color may bleed through the paint layer especially when the paint color is white.
Applying sealer helps to block UV rays from hitting the paint coat and stops the paint color from fading.
If the sealant turns yellow over time, do a light sanding and remove the sealant and apply a new coat to give the paint its life back.
Does Polyurethane Make White Paint Yellow?
Yes, polyurethane makes white paint yellow over time when it gets exposed to UV rays. to prevent that never apply oil-based polyurethane over white paint.
Apply water-based polyurethane over white paint to keep the same white color for so long with no discoloration or yellowing.
You should clean the polyurethane coat from time to time to remove dust and debris and it’ll give back its natural clear finish. Not like an oil-based polyurethane finish.
Did I cover all you wanted to know about: Does Water Based Polyurethane Yellow?
In this article, we deeply discussed, does water based polyurethane yellow and why oil-based polyurethane yellow while water based doesn’t.
We have discussed what makes polyurethane yellow and how to stop yellowing with some practical fixes.
Water-based polyurethane does not yellow since it does not react with UV light like oil-based polyurethane which causes yellow upon oxidation. Use quality water-based polyurethane products to prevent even the slightest yellowing over time. apply thin coats of polyurethane and sand between coats to keep polyurethane from yellowing.
Furthermore, I’ve answered some frequently asked questions as well.
Hope you learned everything you wanted to know about why does water based polyurethane yellow while oil-based does.
Apply water-based polyurethane over popular oil-based polyurethane for woodwork that you need to stay fresh and the same as new for so long.