Recently, Spray Pump, Inc., of Baytown, Texas, needed to spray polyurea on the walls (wood) of temporary buildings at a correctional facility. The challenge was to create a fail-safe barrier or seal that would prevent screws from being removed from the walls. Why? So inmates could not remove the screws and either create holes for escape or use the screws as weapons.Willie Herrington, at Spray Pump, Inc., was asked to conduct field tests to find an application that would speed up the process. The material Herrington used was the Bearcat Industries SL-400 Polyurea. Before the field test, Herrington was using the Graco® Reactor® E-10 with a 2K Ultralite Gun. The application was good but extremely slow.
In Test #1, Herrington used the Graco Fusion Air Purge gun and the E-10 heated proportioner.
Herrington used the E-10 proportioner with heat and tried several different configurations of the Fusion Air Purge gun. Application productivity was greatly increased in this test.
Results: Herrington found that the Fusion AP had too much flow for the given application. Using the GX-8 gun would be too cost prohibitive; i.e., selling it with an an E-10 package. A suggestion was made to try Graco's new Fusion CS.
For Test #2, Herrington picked up the Graco Fusion CS with a round mix chamber and used a E-10 heated proportioner. Fluid temperatures were set at 125F for the A and 130F for the B. Spraying pressure was 1700-1800 psi.
Results: Herrington tested the gun using the variable flow setting, reducing the flow to the desired rate. This was a great improvement over the Fusion AP, but there was a problem: one side of the pattern had a much higher millimeter build than the other - a condition unacceptable to the end user. The test results were better than those of the Fusion AP, but not quite to what was needed.
Test #3 was similar to Test#2, but Herrington used a Graco Fusion CS with a flat mix chamber and a flat tip (FT0424 tip). Again, he used an E-10 heated proportioner and A and B temperatures of 125F and 130F, respectively. His spraying pressure was 1850 psi.
Results: Using a flat mix chamber solved the inconsistent pattern problem that the round chamber produced. Bearcat Industries found the production and quality of finish to be acceptable. Herrington commented, "The spray test was performed and the results were beyond my expectations. We were able to maintain 1850 psi and the product sprayed like an automotive finish. If I had not seen it with my own eyes, it would have been hard to believe.”
As a result of this test, the Fusion CS earned its credibility in the coatings market. It may present a lower-cost alternative to the GX-8 gun for low-output polyurea applications.
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