Frequently Asked Questions

Frequently Asked Questions

Frequently Asked Questions


What is Polyurea?

Polyurea is an organic polymer that is the reaction of isocyanate with an amine terminated polyether resin, forming a plastic-like or rubber-like compound that is seamless membrane.

Can anyone apply Polyurea?

Polyurea requires special training and equipment for field application, whether used as joint filler or as a field applied coating. Shundi has an ongoing program of contractor training in place. There are qualified applicators in China. 

Where can polyurea be used?

As a general rule, Shundi polyurea can be employed to contain any substance that may be directly discharged into normal sanitary sewer systems. It can be applied on any concrete, metal, wood, fiberglass, ceramics surfaces.

What kind of temperatures will polyurea withstand (and will it burn)?

Shundi polyureas begin to develop their physical properties within minutes of application.  Cured polyurea can resist temperature from -40 ℃ to 120 ℃, While polyurea has high glass transition and heat of deflection temperatures, it will burn when exposed to direct flame. It will self- extinguish when flame is removed. But we also have fire-retardant polyurea for special requirements such as subway tunnels and traffic ways.

Is polyurea hard or soft?

Polyurea may be either hard or soft depending on the particular formulation and the intended use. Durometer ratings may range from Shore A 30 (very soft) to Shore D 80 (very hard).

What’s the difference between Aliphatic and Aromatic polyurea systems?

Actually there are two different types of aliphatic polyurea systems currently on the market.  One is the typical high pressure/temperature sprayed systems and the other is what is known as a “polyaspartic polyurea” type system.  This polyaspartic system is different in that it uses an ester-based resin component and has a longer pot life.  It can be hand applied using rollers; brushes; rakes or even airless sprayers.  The aspartic systems are not the high build coating typical of the “hot spray” polyurea systems.   The typical aromatic polyurea systems must be processed through high pressure, heated plural component pumps and sprayed through an impingement type spray-gun.  This is true also for the aliphatic version of this type of system, the primary difference being the color stability of the aliphatic systems.

Application Specific Questions Can you give an overview of the chemical resistance of polyurea to solvents, acids, treated water, etc?

Each product on our website has Chemical Resistance charts under the Documents tab.

One of our workhorses when it comes to very harsh chemical exposure is SWD959 Furthermore, if you have a specific chemical you’re dealing with (or a specific application), feel free to contact us so we can help you determine the best system for your needs.

We have moisture cure urethane coating and rigid polyaspartic coating which have high performance of chemical resistance to solvents, acids or other solvents. It can resist 50% H2SO4 and 15% HCL.

Besides shrinkage during cure or cooling of standard aromatic polyurea liners, is there a specific shrinkage or creep we need to take into account for long-term liner systems?

It does depend on the formulation, although in Shundi’s particular formulations, the polyurea will not shrink after it has cured.

However, this is a good question to ask of anyone you choose to buy material from – does your material shrink or not?

Do you have some kind of polyurea with anti-abrasive and anti-adherent characteristics for mining trucks?

We have the perfect product for this type of application, SWD9005, This product has been tested extensively in the mining industry, and has consistently performed above expectations.

I hear some companies saying polyurea is not as good as epoxies when it comes to corrosion protection. Can you point out how polyurea is better than epoxy on metal? Also, do you have any good 10-year case studies on immersion / metal projects?

For immersion / steel applications, keep in mind that PUA (polyureas) and epoxy are not the same. They are both descriptions of technologies / a product type. PUA systems do work well for immersion, but they must be properly formulated for that application.

While epoxy systems are significantly more rigid, PUA systems have superior flexibility and low permeation rates for properly formulated systems. PUA is also a much quicker return-to-service material in general — polyurea cures within hours compared to days (or sometimes weeks) for epoxies. However, the big issue with this type of work and steel substrates is that surface preparation is critical. This MUST be done properly / completely. This is where most have had issues when attempting these type projects.

Check out our Application cases pages for profiles on this and many other types of applications.

What kind of paint to use when going over polyurea?

Generally, a good quality 100% acrylic latex house paint works well over sprayed polyurea. It is usually best to coat over the polyurea (sooner rather than later) within 24 hours of application. This promotes the best adhesion. Polyaspartic uv resistance topcoat is recommended to use over polyurea for better anti-aging and weather resistance.