I am writing this post to hopefully help some to understand what happens when you incubate and hatch at to high humidity. First let me say I am not in any way downing anyone that says different just read please and use some common sense and maybe what I say will make sense. I am using all layman terms so as not to confuse anyone. If you disagree fine no prob but please read maybe how I say it may make you think. First if you crack a egg open you have the yolk food supply for chick the unbilical cord and what is the white of the egg. Duh huh. The whiteis where the chick floats and cushions the chick. When you set your eggs for the first eighteen days to develope the white must start to evaporate to form the air sac. This air sac has to be water free. If you incubate at higher humidities this vital evaporation will not occur thus water in air sac drowning of chick. Point being go walk in a tropicl jungle high humidity you walk through you come out wet. Follow the size of your air sac its the best indicator of humidity being to high or to low. The last three days when eggs go to hatch You want to raise your humidity just enough to not add water to the egg but to maintain the membrane from drying out when they pip and zip. If humidty is to high you are adding water to the egg through the pores in the egg shell and it accumilates in the air sac so when chick pips through membrane water present chick drowns. How may of you have hatched a couple and your next post is help chick pipped died in egg. Most times and the highest death toll on chicks is drowning from to high humidity either in incubation or during hatch. I have read and not putting anyone down people say raise your humidity to 65 and all the ones even higher like 70 and even some higher then that I cringe. Everyone means well on here and all are trying to help. I have been hatching for twenty five years and will tell you if you follow directions with the styrafoam bators you are doomed to more failure thenvictory. Cant name the hatchery but my sister in law has worked for one of the biggest egg hatcheries in the united states for years.They ship thousands of chicks every day all over the world. After following instructions and failing she finally for me went and started asking questions on their hatching techniques this I tried and could not believe the difference it made. They hatch ninety to ninety five percent of their eggs and now so do I unless shipped but even those went way up unless the post office destroyed them. I took the time to do this sorry so long because I love chickens and I know all you do too. I have heard some say that if I get two chicks I will be happy just think how happy you would be if almost all hatched. Thanks for reading just think about it and hope it helps