What happens when the incubator is openned too soon?

[muslw4]

Ok, I am currently at the end of a hatch. I was just wondering what happens if you open the incubator before all pipped eggs are fully hatched. I keep reading that you shouldn’t open the incubator too soon, i.e. don’t open the incubator in “lock down” or before all pipped eggs hatch. I was curious as to why? Does it mess up the humidity or temp? Or is there another reason? What is the scientific reason? I’ve searched the forum for the answer and even “googled” it. I just keep coming up with all the usual stuff. Maybe the answer is in a long thread that I haven’t read far enough into. I thought it would be nice to have the answer in a shorter thread for other novices that may not know the reason.
Thanks!

 

[brahmabreeder]

It reduces the humidity and the hatching chicks need a high humidity to hatch. Not a high enough humidity egg shells wont get soft enough and the chicks will have a hard time hatching.

 

[sumi]

If you open the incubator the humidity will drop and that can cause the membrane around the chick to dry out, resulting in what we call a "shrink wrapped" chick that will have difficulty hatching by itself.

 

[Sally Sunshine]