If type IV fluid remains on the surface for an extended period, what could potentially happen?

Type IV de-icing fluid is designed to provide anti-icing and de-icing properties by forming a protective layer on aircraft surfaces. If this fluid remains on the surface for an extended period, it can lose its effectiveness as it becomes dehydrated. Dehydration occurs as the fluid retains water vapor over time, leading to a decrease in its protective qualities.

When the fluid dehydrates, the concentration of active ingredients can increase, impacting the fluid's ability to effectively prevent ice formation. Therefore, while it is important for the fluid to remain hydrated to maintain its protective characteristics, prolonged exposure to environmental conditions can cause the water in the fluid to evaporate or be absorbed into the surface, oversaturating it.

Evaporation is another process that affects the fluid, but dehydration specifically refers to the loss of water content that changes the chemical composition of the fluid itself, potentially compromising its functionality. The possible freezing of de-icing fluid would occur under specific temperature conditions, but the primary concern with extended exposure is the loss of water. Thickening might happen as fluids lose water and become concentrated, but dehydration is a more direct consequence of prolonged exposure.