We tried our first hatch in a DIY incubator made out of a thick 1.5" foam cooler and had a hard time getting humidity over 35-40% humidity. I bought a 2 layer plastic with foam core cooler, a standard coleman type, and moved all the components into it yesterday. In the foam incubator a 8"x11" tin was used. In the plastic cooler we have an 8" round tin and humidity was over 50% with vents open. We had to put bowls in the tin to get humidity down to 30%. The volume of the new cooler is at least double if not triple the foam cooler. So does anyone know why this would make sense? It seems to me that with a constant temp the RH should be related to both the surface area of the water and the volume of the incubator. Does the foam have an adverse effect that I am not aware of? This is purely for my curiosity and maybe it will help someone else choose a cooler in the future.