Honeycomb Core and the Myths of Moisture Ingression

While it is true that honeycomb core can trap moisture, it is a myth that widespread moisture ingression is an inevitable outcome when honeycomb sandwich structures are exposed to real world environments. It is also a myth that when moisture ingression occurs, progressive weight gain and strength loss are inevitable outcomes. Using a rebuttal of a 2004 honeycomb-critical paper as the focal point, this paper summarizes multiple sources which indicate both that moisture ingression is preventable and, even if it does occur, that proper material choices can prevent severe consequences. These claims are further supported by results from in-plane compression testing of typical (0.064 g/cm3 aramid-paper/phenolic core with 0.116 cm carbon/epoxy faces) composite honeycomb sandwich specimens after impacting, water submersion, and extensive thermal cycling.