Applying Polyurethane on White Paint (Without Yellowing)

Polyurethane is a sure-fire way to make painted surfaces more durable. Aside from making painted surfaces scuff-proof, polyurethane also makes paint more moisture and heat-resistant. Moreover, they help protect surfaces from UV radiation that causes paint to fade.

However, oil-based polyurethane is prone to yellowing over time. Hence, this type of polyurethane is not suitable for white and light-colored paints. Fortunately, there are other options to protect your surface and prevent yellowing.

In this post, we’ll talk about how to use polyurethane on white paint (without causing yellowing over time), and other non-yellowing top coat alternatives for your painted surface.

KEY TAKEAWAYS

To prevent yellowing, use water-based polyurethane on white paint and other light-colored paints. Alternatively, polycrylic and epoxy resin are great for white paint.

Can you apply polyurethane on white paint?

Polyurethane is perfectly fine to use on white paint, as long as the polyurethane is water-based.

Oil-based polyurethane, on the other hand, is notorious for yellowing over time, which taints the hue of white paint, and other light-colored paints. This color change is caused by an oxidation reaction in the oil of the paint. The oxidization can be accelerated from exposure to UV light. 

Water-based polyurethane is composed of water which is not prone to oxidation (the process that results in yellowing) and it’s UV resistant as well. 

Moreover, water-based polyurethane paint has comparatively fewer VOCs than oil-based polyurethane paint. This makes it relatively less toxic and poses less risk to your health during and after use.

Related: Here’s What Happens If You Don’t Wax Chalk Paint 

Best non-yellowing top coat for white paint

White paint compliments practically any home décor.

However, scratches and dents are particularly noticeable on white and light-colored paint. That said, a topcoat is particularly important for white paint. 

Below you can find some excellent non-yellowing topcoats for your paint project.

Water-based polyurethane 

As discussed, water-based polyurethane is one of the most popular solutions for sealing white paint and lighter colors. It works the same way as oil-based polyurethane, except it dries quicker, has lower VOCs, and releases a relatively milder odor during application.

The key advantage of polyurethane is it’s extremely durable compared to other top coats such as wax. It’s resistant to scratches, water, oil and grease. Polyurethane also comes in a variety of sheens from matte to ultra glossy. 

Note that it’s best to wait until your paint has fully cured, not just dried, before application. To apply your polyurethane, use a high-quality synthetic brush to apply thin layers to prevent unevenness and air bubbles from forming. Wait two to six hours for the polyurethane to cure before applying the second coat.

You can stick with one coat but for maximum durability two or three coats is best, especially for a piece of furniture in a high-traffic area of your house. Note that you can sand lightly with 220+ grit sandpaper to smooth out any unevenness between coats.

Recommended product: Varathane Water-based Polyurethane (available here on Amazon)

Polycrylic 

Polycrylic is a water-based topcoat by Minwax that comes in gloss, semi-gloss, and satin sheens. It has a milky white color and runny consistency, but it dries clear. It is also a great alternative for white and light color paints as it is non-yellowing, durable, and easy to use.

The appeal of polycrylic is it offers the same tough durability of polyurethane, but is slightly more affordable and has a relatively short dry time. 

To apply polycrylic use a high-quality, synthetic brush with very fine bristles. Apply in a thin layer, ideally following the wood grain or paint brush strokes. Amazingly, polycrylic will dry in less than an hour, however, conditions such as humidity and temperature can substantially impact the dry time. Wait at least 24 hours before moving your furniture where you want it in your home. 

For maximum durability apply three coats at the very least. 

Recommended product: Minwax Clear Polycrylic Protective Satin Finish (available here on Amazon)

Epoxy Resin

Epoxy resin might seem like an unlikely topcoat for white paint since some types can yellow over time. However, there are now several options for non-yellowing, UV-resistant resins. Some popular options include:

  • Promise Table Top Epoxy 
  • ArtResin Epoxy
  • Stone Coat Countertops Epoxy

Epoxy resins are generally more labor-intensive and difficult to apply than polyurethane and polycrylic. After all, applying epoxy involves pouring liquid epoxy onto your surface, which is much more challenging than simply brushing a finish on a surface. However, the trade-off is epoxy resin is an extremely durable top coat (more so than polyurethane and polycrylic). When dried, an epoxy finish is practically like a clear fiberglass coating. 

It can typically withstand high temperatures (depending on the brand) and is generally unaffected by chemicals common in household cleaners. The brands we’ve listed above are also self-leveling, so you’ll always get a smooth, even finish.

Note that epoxy doesn’t stick well to oil-based paints. It’s best to use on water-based paints or acrylic paints

Recommended product: Promise Table Top Epoxy (available here on Amazon)

How to seal white chalk paint without yellowing?

Chalk paint is well-known for its beautiful matte finish and easy application. However, it is particularly important to properly seal chalk paint. Chalk paint is especially prone to scuffing so proper protection for your chalk-painted surface is key. 

While you can also use the options above to seal white chalk paint, it’s best to use wax instead. Wax has a lovely matte finish that compliments the soft matte finish of your chalk paint. Generally, people avoid making chalk paint glossy

Note that wax may not be as durable as the options listed and requires regular reapplication. If you don’t want to deal with this hassle but you’re dead set on having a matte protective finish, opt for matte sheen polycrylic instead. 

Other precautions to take to avoid yellowing on white paint 

Under some circumstances, polyurethane can severely cause ambering (yellowing) in white-painted surfaces over time. However, polyurethane isn’t the only reason why light paints can yellow over time. Certain types of paint are also naturally prone to yellowing with or without a sealer. Additionally, tannin stains can cause yellowing to come through white paint as well. 

Use Shellac-based primer

Shellac-based primers are specially formulated to prevent tannin bleed-through that can cause a yellowish-looking stain. Tannins are essentially chemicals found in the sap of dark woods like mahogany and oak. This type of primer also seals smoke and water stains on your wood surface. 

This primer can dry in as little as 30 minutes (still dependent on weather and temperature during application). 

Avoid oil-based paint

As a rule of thumb, always avoid oil-based paints when it comes to light paints. As with any oil-based medium, oil-based paints are prone to oxidative aging. This process of oxidation is a chemical reaction that turns light-colored oil-based paint yellow over time, and is expedited with exposure to UV light. 

Oil-based paint may be more durable, but it is also more toxic. So if you can, always opt for water-based paints, especially when you don’t have good ventilation in the areas where you’re painting. 

 

Sources: 

https://www.varathanemasters.com/products/ultimate-polyurethane-water-based

https://www.minwax.com/en/products/protective-finishes/polycrylic-protective-finish

https://www.rustoleum.com/product-catalog/consumer-brands/zinsser-products/shellac-base-primer/b-i-n-shellac-base-primer

 

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