The old adage “time reveals all things” rings true, especially when it comes to discussing the potential yellowing of water-based polyurethane—a common concern amongst DIY enthusiasts and homeowners alike.
Many, including myself, have a preference for water-based polyurethane due to its crystal-clear finish, but the looming question of whether it succumbs to yellowing over time cannot be ignored.
So, I’m here to shed light on the matter and help determine if water-based polyurethane truly stands as a reliable option for those seeking a clear, non-yellowing finish.
How Come Water-Based Polyurethane Does Not Turn Yellow?
Water-based polyurethane doesn’t turn yellow because its chemical composition doesn’t oxidize when exposed to direct sunlight’s UV rays.
Because solvents and volatile organic compounds (VOCs) are known to cause yellowing in some finishes, the decreased presence of these components in water-based polyurethane helps to maintain the product’s original color over a longer period.
Due to its ability to maintain clarity and resist yellowing over time, water-based polyurethane has become a popular choice for those seeking a wood finish.
In addition, this option is also preferred by many people who want to preserve their wood’s natural beauty and color without the worry of discoloration over time.
However, if you want to avoid wood finishes that take on a slight yellow color as time passes, it is crucial to choose water-based polyurethane, which is a high-quality product, as some cheaper options may not be up to par.
What Causes Polyurethane to Turn Yellow?
Water-based polyurethane is distinguished from oil-based polyurethane by its lack of yellowing over time. In oil-based polyurethane, yellowing is caused by oxidation over time, with a molecule called chromophores responsible for the yellow color on the surface.
Exposure to UV light in direct sunlight quickens the oxidation process of oil-based polyurethane, leading to the polymer undergoing oxidation and eventually developing a yellowish appearance.
However, water-based polyurethane has no chromophores, making it less likely to undergo yellowing. In addition, its chemical makeup is resistant to oxidation under the influence of UV rays from sunlight [1], further reducing its possibility of yellowing.
What Type of Polyurethane Does Not Turn Yellow Over Time?
Regarding polyurethane coatings, water-based options are highly preferred over their oil-based counterparts. In particular, water-based polyurethane is regarded as the top choice for achieving a clear finish that does not yellow over time.
This is due to its unique formulation, which utilizes water as a solvent instead of harsh chemicals that can cause discoloration.
Regardless of how well-crafted oil-based polyurethane products may be, they will inevitably yellow as time pass by, even with proper maintenance. This is due to oil-based polyurethane’s natural amber or yellow color, which becomes more prominent as it ages.
However, low-priced water-based polyurethane may turn yellow as time passes. This occurrence is often due to their low-quality chemical composition, which is nothing compared to more expensive options.
In addition, it can also result in a less durable finish and prone to discoloration, ultimately diminishing the appearance of the surface.
Thus, to avoid such a problem of yellowing caused by polyurethane, below are the best non-yellowing polyurethane products that can resist color change over time.
- Loba WS 2K Supra
- StreetShoe Polyurethane
- Bona Traffic HD Polyurethane
- Varathane Ultimate Water-Based Polyurethane
- Minwax Polycrylic
Methods to Fix Polyurethane That Has Yellowed
- Remove the existing polyurethane coating and initiate a fresh application using a high-grade water-based polyurethane solution.
- To reduce or diminish the yellowish hue of polyurethane, use synthetic illumination to deactivate its chromophores.
- Using a cloth, apply mineral spirits to the discolored sections of the polyurethane surface and rub them.
Why did my water-based polyurethane turn yellow?
Water-based polyurethane may gradually turn yellow due to several factors, including direct exposure to sunlight, elevated humidity levels, indoor humidity, or tannins in materials like leather or wood used in the vicinity.
Exposure to sunlight results in discoloration or a yellowish tint, which increased humidity levels can hasten. This can be a concern for homeowners who want to maintain their surfaces’ natural color and appearance.
Moreover, polyurethane mixed with tannins, organic compounds naturally found in materials like leather and wood, can produce a yellow stain and further enhance the yellowing process.
Regularly applying a UV sealant and maintaining a controlled indoor environment can prevent the fading or yellowing of wood and leather materials. Moreover, using water-based polyurethane products that contain ultraviolet inhibitors can aid in preventing fading and discoloration.
Do All Polyurethane Types Turn Yellow Over Time?
Polyurethane products are not universally subject to yellowing. In particular, oil-based polyurethane may develop a yellowish tint as time passes, while water-based ones are not prone to yellowing. This is because the composition of the two products differs.
The presence of oil-based chromophores in polyurethane renders it susceptible to yellowing when exposed to light. Ultraviolet (UV) light exposure, in particular, can hasten the yellowing process, leading to a yellowish tint on the surface of the cured coat as time passes.
Nevertheless, using high-quality products is crucial when using water-based polyurethane for finishing. Lower-quality and inexpensive water-based polyurethane products may exhibit some yellowing over time due to inadequate chemical composition.
What Are the Ways to Prevent Polyurethane from Yellowing?
To avoid the yellowing of polyurethane, it is essential to reduce the exposure of woodwork or furniture coated with polyurethane to ultraviolet light.
Thus, I recommend to place woodwork or furniture indoors, away from direct sunlight, or use ultraviolet filters for windows blocking UV rays from entering your home.
Moreover, applying a thin layer of polyurethane and then sanding between every application can help avoid yellowing. In addition, by avoiding common mistakes during the application, you can keep your polyurethane clear and prevent it from yellowing.
Thus, it is important to be cautious and fix any issues that arise during the application process. The methods mentioned above can help protect the polyurethane finish from discoloration and maintain its original appearance for longer.
What Is the Lifespan of Water-Based Polyurethane?
The lifespan of oil-based polyurethane is approximately ten years, whereas lower-quality of water-based polyurethane usually has a shorter lifespan of about five to six years.
Thus, the quality of polyurethane is an essential factor in determining its durability, and high-quality water-based polyurethane may last longer than those lower-quality ones.
However, the lifespan of water-based polyurethane on wooden furniture can be affected by multiple factors, such as the application method and the environmental conditions where the furniture is placed.
The type of wood and the thickness of the polyurethane coating are also significant factors that can impact the durability of the finish. In addition, proper maintenance of the furniture is also crucial to preserve the quality and durability of the polyurethane coat.
It is necessary to grease regularly and remove any built-up dust or debris to ensure the polyurethane coat lasts longer. Simple cleaning techniques like wiping with a clean cloth or vacuum cleaner can effectively remove these particles.
See Also: Best Water-Based Polyurethane for Floors
Is It Possible to Paint Over Polyurethane That Has Turned Yellow?
Yes, it’s perfectly fine to apply a new coat of paint over polyurethane that has yellowed. To ensure a successful application, start by meticulously cleaning the surface to eliminate all traces of dust, dirt, or debris.
Once that’s done, grab some fine-grit sandpaper and proceed to sand the surface evenly, creating a suitable texture for the new paint to adhere to firmly.
To enhance the adhesion of the paint and prevent chipping or peeling, apply a primer coat to the area before painting. Finally, apply your desired paint color and finish, allowing each coat to dry completely before applying the next.
These steps will help you paint over yellowed polyurethane effectively and guarantee your furniture or surface a fresh and new look.
However, keep in mind that to avoid any discoloration and achieve the desired paint color, it is necessary to eliminate the layer of yellowed polyurethane before painting. This is because yellow can seep through the paint layer, especially if you paint white.
Is It True That Polyurethane Causes White Paint to Yellow?
Polyurethane has been known to cause white paint to turn yellow. However, it is crucial to avoid using oil-based polyurethane to avoid the yellowing of white paint caused by UV exposure.
This is because oil-based polyurethane has a natural amber or yellow hue that can taint the white paint and cause it to turn yellow as time passes. To maintain the original white color of the paint, it is advisable to opt for water-based polyurethane instead of oil-based.
This way, the white-painted surfaces will remain bright and beautiful for an extended period. By taking this precaution, you can prevent discoloration and preserve the pristine look of your white-painted surfaces.
Conclusion
Yes, it’s true that water-based polyurethane might experience some yellowing as time goes on. However, compared to its oil-based counterpart, it shows a greater resistance to this color change, preserving its clarity and color integrity for a longer duration. Several factors might contribute to the yellowing of water-based polyurethane.
Nevertheless, by investing in routine maintenance, shielding the surface from direct sunlight, steering clear of extreme temperatures, and opting for a top-tier product from a reputable brand, you can significantly mitigate the risk of yellowing and maintain the pristine appearance of your finishes.
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
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