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Two commercial hydrophobic coatings: StaClean™ with a water droplet contact angle of 101° and Wearlon® Super F1-Ice with a contact angle of 115° and one superhydrophobic coating: HIREC 1450 with a contact angle of 152° were studied combined with a thermoelectric anti-icing system under icing conditions. All coatings and the reference surface were tested under glaze and rime ice. The deicing tests were conducted in the Anti-icing Materials International Laboratory's (AMIL) low speed closed loop Icing Wind Tunnel with 0.4 g/m₃ liquid water content, a 26.7 ± 2.6 μm water droplet median volumetric diameter, 21 ± 0.5 m/s air speed and temperatures of -5 and -20 ± 0.5°C. For these tests, a 4\mi chord NACA 63-415 airfoil 2D blade box-section of 10\mi covered with a thin aluminum sheet protected at the leading edge and on the bottom by a thermoelectric anti-icing system composed of two 1/2\mi x 10\mi heating elements with a power density of 40 W/in₂, was used.

Deicing and anti-icing fluids are used to remove and prevent ice formation on aircraft before takeoff. Holdover times (HOT) published by the FAA are used by pilots as guidelines indicating the amount of effective time of a fluid under certain freezing precipitation types. However, the times on these tables are based on endurance time tests involving a visual estimate of failure on a flat plate [1]: when 30% of the fluid is covered with white snow under snow precipitation, although the times have been correlated to aircraft wing tests [2] they do not address the mechanism of fluid failure. To measure and understand the fluid mechanisms conducting to failure, the Anti-icing Materials International Laboratory (AMIL) developed a simplified test with a generic deicing propylene glycol-based fluid. The test consisted of pouring 400 mL of the generic deicing fluid on a 5 dm by 3 dm level flat plate where the plate edges were rimmed with insolated walls to make a waterproof open box.