Chicken eggs need a relative air humidity of 55 percent to hatch. Low air humidity causes eggs to lose moisture. When the egg dries out, the chick sticks to the shell and will not hatch. You can use a wet bulb thermometer to determine the amount of humidity in the air and get humidity by utilizing a pan of water. The heat in the incubator will cause the water to evaporate and create humidity in the incubator that the chicken eggs need to hatch.
Things You'll Need
- Heated egg incubator
- Medium high edged baking pan
- Large high edged baking pan or sponges
Fill a high-sided baking pan with water and place it into the bottom of the incubator. The surface of the water in the pan needs to be half as large as the surface of the egg tray. Run the incubator for 24 hours at 100 degrees Fahrenheit.
Wrap the end of the bulb of the thermometer with wet cloth and place it in the incubator. Let it sit for five minutes and read the thermometer. Write the temperature down. The wet bulb should read between 85.4 degrees and 87 degrees Fahrenheit, which is 55 percent humidity. Monitor the humidity in the incubator daily to ensure that you keep it at the right percentage for the chicken eggs to hatch.
Increase the humidity during the last three days of incubation to 65 percent, 88 degrees Fahrenheit wet bulb or 99.5 degrees Fahrenheit dry bulb reading. Replace the medium baking pan with a large baking pan filled with with water or add four sopping wet sponges to the bottom of the incubator to increase the humidity.