A Guide to Polyurea Spray Guns and Best Practices for Application

An Introduction to Polyurea Spray Guns

Polyurea spray coating systems have become increasingly popular in industries like construction, automotive and marine for their ability to provide durable, seamless and waterproof protective coatings. At the heart of these polyurea systems is the polyurea spray gun, which allows applicators to easily and efficiently apply polyurea coatings to a variety of surfaces and structures.

Polyurea itself is a fast-curing polymer formed by the reaction of an isocyanate component and a resin blend component. When these two components meet at the tip of a polyurea spray gun, they rapidly polymerize into a durable, rubber-like coating. Polyurea spray guns allow this reaction to occur seamlessly and with precise control, making it possible to coat complex shapes and surfaces with ease.

How Polyurea Spray Guns Work

Polyurea spray guns work by combining the two reactive components right at the spray tip. Most polyurea spray guns are impingement mix guns, which means they have two separate hoses - one for the isocyanate and one for the resin. These components are kept separate until they reach the spray tip, where they intersect in a mixing chamber.

As the isocyanate and resin impinge upon each other, they immediately begin to react and form polyurea. The spray tip atomizes this mixture into a fine spray pattern that can be applied in thicknesses ranging from a few mils up to several inches. The polyurea cures rapidly, often within seconds, forming a tough, rubbery coating.

Polyurea spray guns allow applicators to adjust pressure, temperature, flow rates and spray patterns to dial in the ideal application characteristics for the specific job. This level of control allows polyurea coatings to be applied evenly and consistently across all kinds of surfaces.

Types of Polyurea Spray Guns

There are three main types of spray guns used to apply polyurea coatings:

1. High Pressure Impingement Guns

High pressure impingement guns operate at very high pressures, usually around 2000-3000 psi. They allow for precise control over the polyurea reaction and can be used to apply specialized low pressure and high pressure coatings. These guns are more complex and expensive but provide the best atomization for smooth, professional-quality finishes.

2. Low Pressure Impingement Guns

Low pressure impingement guns work at around 1000-1600 psi. They provide a nice balance of control and affordability, making them a popular choice for many polyurea coating applications. Lower pressure reduces overspray and material waste.

3. Heated Spray Guns

Heated spray guns feature electric or combustion heaters to preheat the polyurea components before spraying. This lowers the polyurea’s viscosity, resulting in better flow and pattern control. Heated spray guns excel at applying thicker polyurea coatings.

Key Components and Features

While polyurea spray gun models differ across brands and types, they all contain some core components:

• A gun body/handle - Ergonomically designed for comfort and control during spraying.
• Separate component inlets - For the isocyanate and resin to remain isolated before mixing.
• Heaters - On heated spray guns to control the pre-heat temperatures.
• A mixing chamber - Where the components intersect and the polyurea reaction begins.
• A spray tip - Shapes and atomizes the reacting polyurea into a uniform spray pattern.
• Adjustable controls - Allows customization of pressure, flow rates, fan width and other settings.

When selecting a polyurea spray gun, key factors to consider are the intended application, required material pressures and temperatures, tip size needed, and any specialized features like an integrated solvent flush system or ergonomic anti-fatigue design.

Polyurea Spray Technique and Best Practices

While polyurea spray guns provide the tool for application, proper technique is critical for achieving high quality, long lasting results. Here are some best practices to follow when spraying polyurea coatings:

• Use consistent, even strokes - Overlapping spray passes by around 50%.
• Hold the gun perpendicular to the surface at a distance of 12-18 inches.
• Maintain proper component temperatures and pressures.
• Allow proper cure time between coats.
• Keep the spray tip clean for optimal pattern width and minimal overspray.
• Use smooth, steady trigger control to avoid applying too much or too little polyurea.

Proper spray technique takes practice, so applicators should experiment on mock-ups first to dial in their process before tackling real projects. Safety is also critical when working with polyurea; sprayers must use extensive PPE and proper ventilation to avoid exposure to toxic isocyanate fumes.

Polyurea Spray Gun Maintenance

Regular maintenance is crucial to keeping polyurea spray guns in top working condition. Applicators should follow all manufacturer instructions for cleaning and maintenance procedures. Some key tips include:

• Flushing guns with solvent after each use to remove residuals.
• Checking and replacing worn or damaged gaskets and seals.
• Inspecting spray tips and cleaning clogs as needed.
• Greasing threads, joints and moving parts.
• Checking hoses and hose connections for wear or leaks.
• Filtering component materials to avoid debris clogging the system.

Well maintained spray guns will have better spray performance, less overspray, more precise control and consistent results from every application.

Conclusion

Polyurea spray guns are the key tool that makes it possible for anyone to safely and efficiently apply seamless, durable polyurea coatings. With the right spray gun and proper technique, polyurea can be applied to protect all kinds of industrial, commercial and residential surfaces from corrosion, abrasion, chemicals and water. Polyurea spray guns allow applicators to tailor spray patterns, film thickness and cure times to suit each unique job. With regular cleaning and maintenance, polyurea spray guns will deliver reliable high-performance spraying for many years.

FAQs

What are the main components of a polyurea spray gun?

Polyurea spray guns contain a gun body, separate component inlets, a mixing chamber, a spray tip, heaters on heated models, and adjustable controls for pressure, flow rate, etc.

What PPE is required for spraying polyurea?

Extensive PPE including a full body suit, gloves, boots, respirator with organic vapor cartridges and fresh air supply is required due to toxic isocyanate fumes.

How can spray technique affect the quality of the finish?

Proper technique like consistent passes, proper distance/angle, smooth trigger control and optimum pressures/temps allows for smooth, uniform polyurea finishes.

Why is maintenance important for polyurea spray guns?

Regular maintenance like flushing, cleaning spray tips, replacing seals and filtering materials keeps guns working properly for consistent, high-quality spraying.

What industries commonly use polyurea coatings?

Construction, industrial, marine, automotive, pipelines, waterproofing, secondary containment, tank linings and more all use polyurea for protection.