Hi Tia. Personally I'd bump the lockdown humidity above 80 without thinking twice if I was even slightly worried about shrinkwrapping, but I just don't like to recommend it to others because so many people are completely convinced that it drowns or suffocates their chicks. That's not something I've ever experienced, and I've more than once run my own (chicken) lockdowns at 85% creeping as high as 90% and sitting there for a full day. I've never had a drowned chick or an even slightly soggy chick from doing this. I've also never had a chick pip internally and then fail to hatch. Everyone who pips internally always manages to hatch by themselves. I'm not claiming to be an expert or a master hatcher or anything but I have experimented with very high lockdown humidities and I think they work fine.
From what I've read about incubation, what I've read in posts on here, and what I've spent time thinking about and experimenting with, I think quite a few people don't fully understand the actual mechanics of how humidity works with regards to the incubation process. Seems to me like the most common problems folk have are either a too high humidity days 1-18 and/or a too low humidity during lockdown. Their chicks drown because of the too high early humidity, and they blame it on the lockdown humidity, because the chicks die during the lockdown period, even though it's really the earlier humidity that's to blame...
I weigh my eggs to gauge correct humidity, which removes a lot of guesswork from the process. That way by the time they hit lockdown I know they have lost the correct amount of moisture. The weighing method is incredibly accurate and helps you to pinpoint whether your humidity problems are occurring in the first 18 days or during lockdown.
