by Teresa Wallace

One of the main questions I get asked by PU Foam applicators looking to start spraying Polyurea coatings is, “why do I have to go to training?” Understandably they have had experience as multiple component chemical applicators, so why do you insist that they attend our training course?

The process of applying PU foam is quite different than applying Polyurea. In this article, I’ll go over some key distinctions and then attempt to explain why a factory with APPLICATION EXPERIENCE (as opposed to only manufacturing knowledge) is crucial before diving into the application of Polyurea Technology membranes.

Spray Equipment

A variety of component spray machines available can be used to spray PU foam systems. Still, they cannot spray the usual polyurea technologies coating and provide the physical performance specified by the company’s TDS. Many of the plural component spray systems on the market are suitable for spraying both PU Foam systems and Polyurea systems; however, it is NOT true that ALL plural component spray systems can spray polyurea systems properly.

PU foam Systems are simpler and more “user-friendly” spraying than polyurea systemsThey come with greater tolerance for ratio accuracy, temperature settings, and spray pressures than you don’t have in spraying Polyurea.

You will get a foam product if you apply PU foam roughly on the ratio. A closer examination of the foam will show that due to its being off ratio, the foam has not expanded as much as it should have increased the foam density over what the manufacturer’s TDS indicates.

When you use PU foam “roughly” according to the ratio, you will end up with a foam product. Close analysis of the foam will reveal that because it is “off ratio,” the foam isn’t expanding in the way it could have. This has led to an increase in foam density. It is not what the manufacturer’s TDS suggests.

It is possible to create a “foam material” that “looks like a fine” by using a variety of spray temperature and pressure settings for spraying PU Foam. It is possible to create a foam product that is in line with the manufacturer’s density and temperature data in their TDS; however, it is no different for the customer who does not send samples to analyze and test. It’s like foam; therefore, it should be fine.

However, this isn’t the scenario in spraying polyurea technology coatings. Polyurea is more prone to spraying off ratio, equipment pressure setting, as well as the heating process of the material in comparison to PU foams. Suppose you spray Polyurea without having the right material viscosity (via heat) and don’t spray at sufficient pressure to produce an effective impingement mixture. In that case, you will fail to create a high-quality polyurea coating.

I’ve seen numerous multi-component spray machines that leak seals for the pump and gun parts and heating units that don’t perform as expected, or machines without hose heaters, which are employed daily to spray PU foams. But when these machines are required to spray Polyurea, they cannot perform the task.

What you can “get away” with spraying PU Foam isn’t possible to do in spraying Polyurea. This alone often causes the mind to shift significantly for spray applicators that spray PU foam. For Polyurea, “close enough is not enough.”

What temperature do I need to place my spray equipment in? Do I need to heat your material drums? How much pressure can I put my machine under? What minimum pressure should I use for polyurea” Can I work with the static pressure or spray pressure setting? What’s the difference?

These are just a few issues we assist new polyurea sprayers in answering and comprehending when they participate in our training classes.

Mixing module / Size of spray tip

With the greater tolerances provided by PU foam and the more tolerant tolerances of PU foam, it is typical that PU foam sprayers to select the most powerful mixing unit for their spray gun. This is fine for spraying massive quantities of PU Foam; however, it is often an issue when spraying a two-millimeter DFT polyurea membrane.

Spray applicators spraying PU Foam through, say, a Graco Fusion gun fitted with a 4242 round mixing module will experience something very different when they try and spray Polyurea through the same setup……………and usually that experience is not pretty……and it’s normally expensive!

As opposed to spraying PU Foam selecting the appropriate mixing modules or spray tips are more essential in spraying Polyurea. This is even more crucial when a particular skid-resistant or more appealing surface finish is desired, like using pick-up trucks, bedliners, boat fenders, etc.

In cold regions, the dimensions of the mixing module could impact the spray machine’s capability to generate and maintain proper chemical temperatures. Polyurea is contained in the heating system for a prolonged time. The more material is pumped through the machine in a minute, the shorter time it takes for the chemical to be within the heating blocks. Creating and maintaining the right chemical temperature is essential in spraying polyurea-based membranes.

What size mixing module do I need to use when spraying Polyurea, and what applications? What is the best time and reason to utilize the spray tip with a fan spray tip? What should I look to ensure I am spraying in extremely cold locations? What should I do if I cannot generate and maintain enough heat within the polyurea chemical device? These and other questions can be answered and explained in our courses for training.

Substrate prep

Substrate preparation is the most significant distinction between PU Foam and Polyurea membranes. In simple terms, there’s minimal substrate preparation needed when using PU Foams, and there are a lot of needs when creating a substrate for the 2mm DFT polyurea membrane.

The significance of substrate preparation before applying Polyurea cannot be understated, and if you fail to comprehend these guidelines, you’ll be prone to many failures.

Each substrate that you apply Polyurea to needs significant preparation. And there isn’t a substrate that I am aware of that requires “cleaned,” like when you apply PU Foams.

Using PU Foam, cracks in the substrate cannot be sprayed over as you would. There’s a specific procedure to follow before spraying on expansion joints. Stopping the lining around edges and fixtures demands different methods and procedures compared to the PU Foam process.

What are the requirements for you to use Polyurea to a concrete substrate, an iron substrate, or maybe to GRP or the timber board that has been compressed? What are the best preparation options? Do I require priming, and which primer should I choose? Should I apply the same primer to each substrate? How can I deal with cracks in the substrate, and what should I do with expansion joints?

These questions and others are addressed and clarified in our training classes.

The purpose of this article is to briefly show that just because you own multiple components of spray equipment and are spraying PU Foam doesn’t necessarily mean you will be able to begin spraying Polyurea membranes successfully. Preparation of the substrate, output requirements, machine setup, and spraying techniques are all crucial considerations in spraying polyurea membranes.

Of course, if you have a well-maintained plural component spray rig with sufficient pressure and heating options, you’re already halfway there. Still, investing in your business and understanding how to use Polyurea properly is vital since it is not as straightforward as spraying PU foam.

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