Just had an awful result with my last batch of eggs in the 'bator. Going into lockdown I weighed them and they'd lost FAR too much weight over the first 18 days. I usually aim for an 11-14% loss, these ones had lost 25%! The air cells were huge but by then there wasn't much I could do about it. Anyway I was going away overnight on 'hatch day' so I thought I'll just leave them to it and see what happens, but I wasn't expecting much. And sure enough only one pipped, didn't even get its beak out, and the rest all died in the shells. Nine properly formed very small chicks, but all shrink wrapped in the eggs. The membranes into the air cells were tough and dry. Which sounds like a humidity problem, right? Humidity far too low. Well... My last hatch I ran at 30-35% then 60-65% for lockdown and did okay, but after taking advice from a few people about how 'dry' hatches weren't always the best idea, I thought I'd bump humidity up for this one and see what results I got. Ran it at 50% then 70% for lockdown. I know by lockdown the damage was done, but I ran it 20% higher than normal for the first eighteen days and ended up with air cells twice as big as they should have been! So what happened to them? My hygrometer is definitely accurate.