If the air cells are on point when you go to lockdown, can humidity ever be too high for a successful hatch?
The birds will never dry out to take out of incubator if your humidity is too high. At some point over time with excessive humidity water gets into the air cell. How many days that takes I don't know. Not to mention if your much over 80% RH all the viewing glass will be covered with condensation so you won't see anything of the hatching. If you don't have a hygrometer then simply add surface area until you get condensation on windows then take surface area out until it stops. That would put you 70-80% Rh range which is a good place to be. I don't use the troughs in incubator bottom rather short cups and double shot glasses siting right on the wire bottom with eggs. Easy to adjust surface area with a few varying mouth sized cups like that. For me it's usually one large mouth and one double shot glass or two small coffee cups to get 70% RH to give you an idea what I'm taking about. Surface area needed of water will vary to peoples specific house humidity.
If you see condensation you need to scale it back. I run 75% at the start of hatch. It often goes up to 85% or even 90%. (Not that it stays there because I remove chicks and egg shells and roll over the ones that got knocked.) The higher humidity, yes, the less your chicks are going to fluff. I put mine in the brooder under the light (I keep my lighted end 100F and out of any drafts) and they dry and fluff up so much better in there.
