A friend one time told me that in theory ALL prepolymer urethanes are hydrophilic, due to fact that the prepolymers react with the OH-group of H-OH water. Mirriam-Webster's Dictionary shows hydrophilic as: of, relating to, or having a strong affinity for water. Based on this definition, my friend was right. All prepolymer urethanes have an affinity for water. So how did our prepolymer urethanes then ever got classified as hydrophilic or hydrophobic? Was it based on the cured or uncured properties of the urethanes? Lets throw in 2 more variables, in how much time does how much water need to be absorbed? The dictionary did not mention anything about time and amounts! We could easily take a material, pump some water on it and let it sit for 100 years, before all the water was absorbed by the material. Does that make the material hydrophilic? I know, very few of us would be able to witness an experiment like that! Lets tackle the issue a little bit more scientifically. Pour an X amount of urethane in a cup and poor an equal amount of H-OH (water) on top. Mix the two products and observe for the next 5 min. If ALL the water is absorbed by the urethane, either by reaction or mixing, I would call it hydrophilic. If any part of the water is rejected, I would call the animal hydrophobic. Is this the correct interpretation of hydrophilic or hydrophobic? Even with scientific established absorption rates it would still be difficult to make the right determination. Each manufacturer, engineer or contractor will have his or her own interpretation on this issue. Will I be offended when you call our hydrophobic --> hydrophilic or vice versa. No! We will still be happy to provide you with the urethanes you want, regardless of the way you call them. At least now you know our interpretation of hydrophilic and hydrophobic.