Increasing Humidity in your incubator.
Hatching eggs with the use of an incubator can be a lot of fun as long as you get some good results. Many times children in classroom experiences end up disappointed when they find no baby chicks at the end of the 21 days of incubation.
Much of this disappointment comes from the last few days of incubating.
During the final 3 days of egg incubation which most call the lock down period of your eggs it is important to increase the humidity in your incubator to around 80-85%. This humidity may vary a few percents and you will still end up with a great hatch.
Important note to remember. During this lock down in the last 3 days KEEP THE INCUBATOR CLOSED. It is very tempting to keep opening and checking or wanting to help a baby chick out of the shell. Normally the chick does just fine on it’s own. The hatching may take several hours. Do not rush the chick.
This also messes up your humidity levels which is very very important during the hatching time.
Many chisk have died in the shell without having the opportunity to hatch because someone just could not leave the incubator closed during this critical time.
To increase humidity in the incubator it is not as simple as just adding water.
To increase humidity you need to increase the Water Surface Area.
Surface area is nothing more than the amount of surface of the water that is exposed to air in your incubator.
humidity for egg hatching
The depth of water has no bearing on the humidity in the incubator. I take that back. if you have no water then of course the depth matters as you have no surface area either 
If you find that the humidity is too low in your incubator, add surface area. Place another pan of water in the incubator or a pan with a larger surface area. You can also increase the surface area by using some small, wet sponges. To decrease the humidity in the case of to much humidity you simply decrease the water surface area.
Simply use a smaller containers of water, or undo some of the things you’ve added.
Happy Hatching!