Found this on a page about hatching ratites:
Hatcher environments need to be adjusted to allow enough humidity to prevent shell membranes from sticking to the chick. Running the hatcher at setter humidity until external pipping and then turning the humidity up to 70-75 % RH has been successful in preventing "sticky" chicks from occurring.
http://www.pleysierincubators.com/incubation_ratite_eggs.htm#humidity
Then I found this that says much lower:
During the final stages of the hatching process and after external pipping, a relative humidity of 30 to 40 percent is recommended. It is also suggested that the hatcher dry bulb temperature be run at 0.5[SUP]o[/SUP]F higher than the incubator temperature since the hatcher will routinely have fewer eggs than the incubator.
http://www.ces.ncsu.edu/depts/poulsci/tech_manuals/emu.html