Humidity is more important than turning this late in the game. Early in incubation when the body parts are forming they really need to be turned. You don’t want the eyes on the inside of the skull or both on one side of the face. The internal organs need to form in the right place so the plumbing will hook up right. Also you don’t want the yolk or developing chick to come into contact with the inside of the egg shell and get stuck. When this happens these chicks normally die in the last few days of incubation.
By 14 days, the body parts have formed and a membrane has formed around the chick so it won’t get stuck to the shell. Although it doesn’t hurt anything to turn them, you can quit turning after 14 days. We normally leave them in the turner until 18 days because that is convenient. That’s when we take the turner out and raise the humidity.
The goal on raising humidity is to get the humidity raised before the eggs pip. After they pip is when you run into the danger of them shrink-wrapping from opening the incubator or the humidity being too low when they pip. This doesn’t mean that all of them will shrink-wrap if you open the incubator when they have pipped. My first couple of incubations I had a few pip before lockdown. My temperature was a little high so they were early. Even though some had pipped before I opened the incubator to take out the turner and raise the humidity, I didn’t shrink wrap all of them. I did shrink wrap one once, so it can happen, but most did not. Still because it can possibly happen, it’s best to have the humidity up before they pip.
Another form of shrink-wrap is if the humidity is too low throughout incubation and they lose too much moisture. That’s probably a more common cause of shrink-wrapping them than opening the incubator, especially if a lot have shrink-wrapped.
Neither the turning nor raising the humidity has to be this precise. The 18 day time is a convenient time to do both, mainly because if your temperature is a little high they can pip this early. I suggest you stop turning and go into lockdown mode on schedule. They can sometimes surprise you. And if you haven’t done it, calibrate a thermometer and adjust your incubation temperature before your next attempt. You don’t have to be exactly precise with the incubation temperature but the closer you are the better your chances for a good hatch.
