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  • Writer's pictureGreen Synergy Engineering

Case Study: Clear Solution for Optical Coatings

One customer manufactures specialty faceplates used in military applications for fighter pilot helmets, motorcycle helmets, and gas masks. Clarity in both the molded part and the Silicone hard coat are critical to ensure that no distortion is formed in the line of vision.

The silicone hard coat solution, with a 10 cps viscosity had a tendency to develop gelatinous contaminants which can be difficult to capture and retain. In addition, hard particulate were also present.

The customer had been using GE's Hytrex and RO.Save products at 1 and 5 micron depending on batch requirements on a continuous recirculation loop from the storage tank. Despite the labeled micron, contaminants larger than 1 and 5 micron were passing through these filters, causing costly faceplate defects and high scrap rates.

This was strong evidence that the GE filters were much lower than 90% efficiency at the labeled rating, and/or were unloading captured contaminant due to inadequate thermal bonding.

Graver's new Stratum Series filters were recommended to replace the GE products; armed with data on how Stratum’s advanced melt blown structure can outperform competitive filters in retention efficiency, gel capture, consistency and on-stream life. Trials were run with 3 different grades of Stratum C filters at 1, 3, and 5 micron.


  • The customer was able to replace the GE 1 micron with Graver's Stratum C 3 micron filters due to the higher efficiency level of the Stratum filter.

  • The STC 3 micron filters resulted in achievement of the ultimate process goal of zero defects!

  • On-stream life improved from 2 weeks to over a month, or a 50% reduction in annual filter consumption.

  • Lower pressure drops were recorded for Stratum compared to GE, despite the higher efficiency of the Stratum.

  • The customer also reported an additional benefit of the proprietary hard molded “Cactus Core” used in all Stratum filters. They felt that the seating in the housing was more stable and reliable, easing concerns about over tightening the GE filters and causing bypass.

The customer plans to continue using STC 3 micron, but are evaluating STC 5 micron filters, which they feel may also deliver the desired contaminant control, but extend filter life/drop consumption even further.

Contact us for a product recommendation.

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