Polyurethane Vs. Urethane: What Are The Differences?

Polyurethane Vs. Urethane: Top 10 Differences with FAQs

You might have heard Polyurethane and Urethane used interchangeably. But are Polyurethane and Urethane the same thing? The two compounds are the same thing but only have differences in their chemical structure.

Polyurethane is a polymer made up of small units of monomers of Urethane. At the same time, Urethane combines an ester and an amide group with carbonic acid to form a chemical compound (SCIENCING).

Urethane is soft and flexible. Spar urethane is used as a paint which is a form of Urethane. Polyurethane is stiff and rigid.

Polyurethane and Urethane are used in manufacturing various related products such as paints and molds. Urethane has a boiling point of 50 degrees Celsius, while polyurethane burns.

So is it okay to use these words interchangeably? Yes, It is okay to use them interchangeably but keep in mind the few distinct features. Today, I will address everything related to Polyurethane Vs. Urethane, their differences, uses pros, and cons.

What Is Polyurethane?

Polyurethane is a polymer made up of multiple small units of monomers of Urethane. Polyurethane is formed through a chemical process called polymerization that joins small teams of Urethane into a polymer. Polyurethane is stiff and rigid and is usually used in place of rubber. In 2019, the production of Polyurethane in the world was 25 million metric tonnes.

What Is Polyurethane?

I was equivalent to 6% of the world’s production of polymers. In the US, Polyurethane is used extensively in various applications in a year; in building and construction, 1,459 million pounds which is 26.8% of the total in Polyurethane in a year, is used.

Transportation uses 1,298 million pounds which is 23.9 of the total Polyurethane used in a year; Bedding uses around 1127 million pounds of Polyurethane which equals 20.6 % of the total employed.

What is Polyurethane used for?

  • It is used in the manufacturing of shoes.
  • Polyurethane is also used in the manufacture of flexible plastics.
  • It is used in the manufacturing of flexible or rigid foams.
  • It is used in paint products to give them a long-lasting effect.
  • Polyurethane is also used as an adhesive.

Types of Polyurethane

  1. Polyester
  2. Polyether


  • Its great look and protection, polyurethane finish gives surfaces a shiny fish and excellent protection against corrosion or water.
  • Polyurethane adapts to low temperatures.
  • Ensures smooth and even result
  • Polyurethane products are durable.
  • Offers protection against moisture, humidity, chemicals, and heat


  • It takes longer to dry.
  • Polyurethane is highly flammable when in liquid form; hence should be used in a well-ventilated room.
  • Rigid and hard to work with when dry.

What is Urethane?

What is Urethane?

Urethane combines an ester and an amide group with carbonic acid to form a chemical compound. Spar urethane is a common type of Urethane used in paints to offer waterproof and resist UV rays.

What is Urethane used for?

  • Urethane is used in the manufacture of pesticides and insecticides.
  • It is also used in the manufacture of veterinary and pharmaceutical medicines.
  • It is also used as a solvent.

Types of Urethanes

  1. Spar urethane


  • Urethane is soft and flexible
  • Easy to dry
  • Easy to apply


  • Urethane is toxic
  • It is less durable
  • Does not dry hard
  • Needs reapplication

What are the Differences between Polyurethane vs. Urethane?

Differences between Polyurethane vs. Urethane

01. Uses

Polyurethane has more uses as compared to Urethane. 6% of polymers in the world are Polyurethane. Polyurethane is used on fences, floors, and walls. Urethane is used primarily on wood-like tables.

02. Amount of Oil

Urethane has around 450g/l of oil, while Polyurethane contains 250g/l of oil.

03. Fumes

Polyurethane emits more fumes, especially when it is oil-based. Urethane also emits fumes but in smaller quantities.

04. Times of drying

Polyurethane takes longer to dry due to the several layers of small units of monomers; one coat can take 24 hours to dry. Urethane takes a relatively shorter time to dry since it is formed of a single layer of esters and can take up to 4 hours to dry.

05. How easy to apply?

Polyurethane is hard to apply since it is less flexible and tends to get stiff as you use it. Urethane, mostly spar urethane, is easy to apply due to its soft nature and flexibility.

06. Durability

I recommend Polyurethane is more durable since it is formed from several small units of monomers comprising a hard thick coat when it dries. Urethane, while Urethane is less durable, needs reapplication after 12 months.

07. Malleability

Polyurethane is stiff and rigid, making it less malleable than Urethane, which is soft and flexible.

08. Toxicity

Both are toxic, but Urethane has a low level of toxicity as compared to Polyurethane. Toxicity in Urethane is below 1% as compared to Polyurethane which can be up to 5%.

09. Ambering

Polyurethane ambers more as its look on oil-based starts to get yellowish and then darker, making you want to change it. Urethane tends to maintain its shiny look for a more extended period.

10. Indoor or Outdoor protection

I recommend using Polyurethane for outdoor protection since it dries hard and can sustain wear and tear. It can also be used indoors on the floors. Urethane is best preferred indoors due to its ability to withstand scratches and dries, leaving a smooth and level surface. It is worth noting that Urethane can almost 90% withstand UV rays and moisture making it a good choice for outdoor too.

FAQs About Polyurethane and Urethane

Can I put Urethane over Polyurethane?

It is okay to put Urethane over Polyurethane. You should ensure that Polyurethane is dry before you apply Urethane. I recommend you first try it on a small part and see the results before deciding to use it on the entire surface.

Is acrylic Urethane the same as Polyurethane?

They are not the same; Polyurethane is usually oil-based while acrylic is water-based.

Does Polyurethane make the wood harder?

No, it doesn’t; Polyurethane does not make your wood harder. It creates a hard coating on it as it dries. It protects the wood from attack or moisture, making it last longer.

Does Polyurethane protect the wood from water?

Yes, Polyurethane protects wood from water by forming a hard coating on it as it dries. The coating prevents water from soaking into the wood.

Should I use lacquer or Polyurethane?

Both have pros and cons; lacquer is then and dries quickly, has high durability, is easy to apply, and is resistant to wear and tear but challenging to use.

Polyurethane is a thick coat that lasts longer, protects against water and chemicals, forms hard skin, and is easy to apply but takes longer to dry. They seem similar in terms of use, but I recommend using Polyurethane.


Polyurethane and Urethane seem slightly like some products but have a lot of differences. It would be best to consider the differences before deciding to use either of the products. I suggest you choose a product that will meet your needs and wants. It would be best if you also considered the pros and cons of the two in making a decision.


  1. I have a small can of polyurethane with wood stain and was wondering if it could be mixed with spar urethane ? Both are water based and will be used on bare mahogany wood on my boat. Thanks for any help with this as most answers out there cover one being water based and the other oil based

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