Difference between Polyurethanes and Urethanes?


Polyurethane was actually invented in the mid-20th century. Resins such as plastic resins in their liquid form are mainly used for things like protecting wood surfaces like woodwork. Some of the main ingredients in Polyurethane are things like mineral spirits, nitrogen based chemicals, vegetable oil, amalgams and isocyanates. The Nitrogen in Polyurethane actually helps keep finishes from chipping away, and the isocyanates tend to make Polyurethane sturdier. The Polyurethane coatings we see nowadays actually cure when chemical agents like the nitrogen mixes with oxygen which creates a really tough and durable material that is really resistant to things like outdoor elements. While Polyurethane is a good option, it of course has negative effects as well such as discoloration over the years. Some of the lighter woods it’s placed on can also take on a darker appearance – definitely not a good thing if you have lighter wood and want to keep it that way.

When it comes to being greener or more ecofriendly, some of the companies out there that create Polyurethane coating, now offer a water based option. The basis of this formula calls for water suspension of the Polyurethane. While these water based options are more vulnerable to wear and tear, they do have benefits such as drying quicker, they have slim to no fragrances and as you would expect from a water soluble product, they are also washable via water. Oil based Polyurethane HAVE to be applied in a really well ventilated area. But, water based Polyurethane, while still hazardous, tend to be less hazardous than oil based.

Oil based Polyurethane are quite picky to be honest. The curing can’t happen if the temperature is too high or too low for that matter. Obviously when it comes to curing, it’s going to be a difficult feat when it comes to really cold temperatures or really humid temperatures. When it comes to water based Polyurethane the house painting contractor in Summit will probably tell you that you are going to need more than one coating – usually 2-3 to take effect. On the other hand, oil based Polyurethane only usually needs one coat to do the job at hand. One of the things that your contractor will probably advise to is to make sure that with each coat you let it dry and then sand it vigorously. Also, it’s important to remember than oil based Polyurethane’s tend to be more flammable than water based which means you will need to take extra care when applying it.

*** Note: When you are using a Polyurethane finish or coating, make sure you DO NOT shake it. The shaking causes bubbles and though they may not appear as soon as you put the coating on, you can be sure that later on down the line the bubbles will appear and you will have to do the job all the way over again. If you need to mix the Polyurethane up, make sure you use a gentle stirring motion. Once it’s mixed up thoroughly, you can then use a soft cloth, soft brush or even a foam brush to apply it to the work surface. Once the finishing has dried – make sure you wait at least 24 hours, you can then sand it down with a gritty sandpaper such as 320 grit. Once you sand it down, remove the dusty debris left behind, as well as any nits of left over material. Once this is done, you can then start the second coat. If you want a high gloss shine, wait for the second layer to dry – another 24 hours and then finish it with 600 grit sandpaper. You can then buff the whole thing to create a really nice high gloss look.

When it comes to the words Polyurethane or urethane – we tend to use these words a lot, even if we armed aware of it or we aren’t a house painter. There tend to be a lot more differences of urethanes vs. Polyurethane than people are actually aware of. Although the biggest difference is the main compounds that these two materials use – Polyurethane tends to use a chain of compounds that are organic and urethane uses a group of functional compounds, they are still different in other ways. For example, Polyurethane tends to stain and chip much less than its counterpart urethane. Polyurethane also tends to be sturdier and stands up to chemical compounds like alcohol. In fact, out of the two, Polyurethane always seems to stand up better and stand up longer than urethane and I think most of the painting contractor will agree to this! But, before I go talking ALL good about Polyurethane you also need to know that there are negatives. For one, it will require more coats than urethane. Secondly, it glosses less easily than urethane. Thirdly and lastly it does dry, cure and set significantly slower than urethane. In fact, urethane takes about 10 minutes to dry, whereas Polyurethane can take anywhere from 4 hours to 24 hours!

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