I know it kinda works, because I have done it with my canary eggs. I have a heap of button quail eggs in my incubator that I just can't candle and I was wondering does it work with those eggs too. Some of the older eggs have passed their due day by 4 days now. I floated all of them and more than half sunk Has anyone ever floated button eggs and how long should I wait to see if any of them hatch? My canary eggs would often go over due because I have a home made still air incubator with no thermostat.