Is Polyurethane Toxic? Simple Tips and Answers


Is polyurethane toxic? This is a question that you will come across almost every other day. Regardless of where you live, small rural towns, or busy cities, the homeowners keep asking that. And you can attribute that to the fact that polyurethane is a durable  finish that offers your home beauty other than protection.

Sadly, scientists found polyurethane to have isocyanates, a compound that can harm your lungs. Therefore, polyurethane is toxic. You must at all cost try to avoid using it and opt for its alternatives such as Tung oil 

What Is Polyurethane?

Polyurethane is a member of a large family of elastic polymers, best known as rubber. They are a little different from the conventional rubber as they exist as liquids.

Polyurethane exists in different forms and shapes. It’s such a versatile compound that makes it the best fit for an abundance of applications as it can quickly work in places of other expensive materials. Other than that, polyurethane is flexible and durable. Therefore, it cuts as one of the common materials for coating and insulation.

There are many health consequences that you can develop after prolonged exposure to this compound. They include irritation of the lung and the skin. Other possible health conditions that this product can cause include asthma attacks.

Individuals with cases of migraines must, by all means, keep off polyurethane fumes as they can make human brain cells swell, which causes severe headaches. Also, expectant mothers, sick people, kids, and the elderly need to stay away from polyurethane fumes. These fumes can trigger colds, coughs, and asthma.

Polyurethane can further cause stomach rumbles, dizziness, and nausea.

Alternatives to Polyurethane

The paints, coatings that you see around you almost all the times are toxic and can have unpleasant side effects in your health. The conventional paints that we use today are extremely toxic. There are less poisonous alternatives that you can consider for use in your home. Here’s the list:

Candelilla Wax

Candelilla wax is a natural plant product. It’s an extract of Candelilla shrub leaves. A decision to use candelilla wax comes with an extra green condition due to its minimal impacts on the environment. 

Vegetarians call candelilla wax a ‘bee-free alternative to polyurethane.’ There are a vast number of beauty brands that use it in place of beeswax. Feel free to use the candelilla wax in a variety of home projects, such as polishing of the furniture or wooden floors.

Green Polyurethane

Green polyurethane is a remodeled hybrid of polyurethane which contains no hazardous isocyanates. It’s a possible near-perfect replacement for polyurethanes that have isocyanates.

Green Polyurethane boast of other added advantages like its coating containing no volatile organic compounds (VOCs). They are 100% solids-based. Polyurethanes resist degradations by other chemicals by up to 30% and 20% more resistant to wear and tear. Green Polyurethane also cures in low temperatures conditions.

Hard Varnish

The hard varnish is another perfect alternative for polyurethane that intensifies the color of your wooden floors. It protects the surfaces of the wood against water infiltration and various stains from potential spills. Hard varnish as a polyurethane alternative is a plant-based oil mixed with a natural hardener. The hardener ensures a durable finish. We suggest that you use hard varnish for floors, cabinetry, wooden toys, doors, furniture, and kitchen cabinets.

Tung Oil for outdoor wood furnitureTung Oil

This oil comes from a Chinese native tree. Its name originates from the leaves of the tree, which are heart-shaped. The name ‘Tung’ means ‘heart’ in Chinese. 

This oil is excellent for finishing as it enhances the appearance of the wood. It has existed and remained in active use for centuries in China. It permeates the wood, and bind to form an impermeable layer that repels water. Tung oil has a protective layer that can penetrate the wood for up to 5 mm.

Using this oil as a preservative works best for the exterior work. It has a thin layer that makes it less useful for the underground set up. Tung oil is light, which enables it to permeate deep into the wood; in the process, it creates a lasting wet look which highly emphasizes the wood grain and highlights its true beauty. 

AFM Safecoat

AFM Safecoat Hard Seal remains an alternative if you are looking to renovate your house. It’s an all-round clear gloss sealer; its manufacturing is to offer high resistance towards physical effects like scratching. Applying it well enables the forming of a continuous hard seal that guards against any poisonous off-gassing, this leaves you with an improved condition of indoor air.

Its hard seal has a reputation of a low-odor, a characteristic that makes it safe around people who are highly sensitive to chemicals. This sealant is best for hardwood or particleboard. It belongs to the family of ‘less toxic’ products with a wide range of sealants and varnishes.

Is there a non-toxic polyurethane?

Yes, there is a non-toxic polyurethane.

There exist different types of polyurethanes (shellac, poly, or clear coat), which have labels like “environmentally friendly,” in the real sense they are not wholly safe. ECOS WoodShield Varnish is an excellent example of a non-toxic polyurethane and, above all, contains no traditional paint odor responsible for health complications mentioned earlier.

Is Polyurethane Toxic After It Dries?

No, as soon as your polyurethane finish dries and cures, it does not pose any threat relating to toxicity. These formulas are very dangerous when dry because it is at that point that they release dissolved chemicals into the atmosphere. 

These volatile organic compounds come with a bad smell that can affect the breathing systems making them dangerous for humans, animals, plants, and the environment.

How Long Is Polyurethane Toxic?

Different brands make different types of polyurethane in terms of thickness and chemical composition. Generally, polyurethane is expected to take about 14 days to cure fully. However, this is not always the case, as the smell could still be around.

Sometimes, the smell lasts up to 6 weeks, during which the polyurethane can still be toxic. Those fumes, when inhaled, can cause respiratory complications. Coming to contact with the uncured polyurethane can also cause skin irritation and or allergy.

Can You Sleep In House After Water Polyurethane?

I recommend that you wait at least 2 days after applying water-based polyurethane before you can sleep in that house.

2 days is the bare minimum. However, it would help if you could wait a little longer, just about 5-7 days, before you can consider sleeping in the house. That duration gives your room enough time to stay clear of possible gassing from the compound.

What Is the Fastest Way to Cure Polyurethane?

Image of polyurethane floor but Can You Put Polyurethane Over Old Polyurethane?Sometimes, different finishes like polyurethane can take longer than expected to cure. If such a thing happens to you, it can be frustrating, especially working on a short timeline. In a bid to avoid possible inconveniences, I’ve provided answers to the question, What is the fastest way to cure polyurethane?

Here are some of the approaches you can undertake to help cure your polyurethane in the shortest duration possible.

Use of a Thinner: Naptha is a great thinning agent, and when you mix it with polyurethane during the preparation, it can help your polyurethane dry and cure faster. Naptha has a high rate of evaporation which plays an important role in drying and curing the poly.

Apply Heat Over the Surface: The use of heating devices can help your polyurethane dry and cure faster. Some of the most readily available heating devices include hair dryers or heat guns.

Apply some heat back and forth to the surface of your polyurethane to help speed up drying and curing. Ensure that you hold the heating device of your choice a distance above the surface to avoid subjecting the finish to too much heating.

Use Water Based Polyurethane: The choice of your polyurethane formula also plays an important role in how fast your polyurethane finish dries and cures. Water based polyurethanes are reputable for their faster drying time, unlike their oil based counterparts which take a little longer to dry and cure.


Polyurethane are reputable for their beauty to the eyes when applied to different wood products such as table, kitchen cabinets, counter tops and a lot more. Additionally, these finishes offers protection to the surfaces which help improve their service life. As it’s normal, many of good thing things comes with their bad sides and polyurethane is not an exception. And that begs the question…

Is Polyurethane Toxic?

Yes, polyurethane especially the oil based one contains a lot of dissolved chemicals which are toxic. When these chemicals, usually released inform of fumes are inhaled would likely cause respiratory health complications.

Up to this point, one thing is coming out clearly that polyurethane is toxic which is why you must protect yourself at all cost whenever you are using these formulas.

I hope you found this content helpful. Do you have a question? A suggestion, or opinion that you would love to share? I hope so, please do that in the comment section below!

Image of a woodworker wearing hearing protectors for woodworking

Tyron Otieno

Tyron is an avid woodworker and writer. He founded this website to help other woodworkers, whether hobbyists or professionals by sharing his knowledge and experiencie after a decade of woodworking.

1 thought on “Is Polyurethane Toxic? Simple Tips and Answers”

  1. I do a lot of wood refinishing, and use a lot of polyurethane–though I use it only outdoors and let it cure thoroughly before bringing it into the house. I suffer from atrial fibrillation (afib), and I’ve found that the fumes from wet water-based polyurethane protectants is a guaranteed trigger for my afib! I don’t know exactly what chemical is the culprit, but I’ve learned to use it only with a large fan behind me to drive the fumes away from me while I work.

Leave a Comment

Your email address will not be published.