I have an egg that pipped approx. 20 hours ago. When I got up this morning, it had cracked a little more around the pip, probably dime sized area. about an hour ago, I looked and it had knocked off some of the shell, about the size of a pencil eraser. The membrane is still there and not poked through. I can see it poke at it every now and then but I don't think it can get through it. I had the humidity at about 70%, but after the hatching started it got up to 80%. I had to open the incubator this morning because one of my chicks had gotten over the divider and was stuck under the light bulb. But I took in the bathroom with the shower running and it was very steamy. The humidity never got below 63%
