Temp/Humidity variations effecting Air Cell Size ?


In the Brooder
11 Years
Feb 9, 2008
SW Washington
First want to thank everyone out there helping all of us novices - this is an amazing source of information and support.

This is our first attempt at hatching so I'm worrying abt everything.

Our incubator was running a little warm (100.4 - 101.0) the 1st 7 days - we've managed to lower the temps to 99.5- 100.0 but it seems to me that the air cell size is larger than pic's in books showing what it should be at day 7. Can I correct this by keeping the humidity higher or is it just best to cross my fingers and see what happens?

Of 11 eggs I have veining in 10 - one looks like maybe infertile

Thanks so much...
What kind of incubator are you using? Still air or forced air? What's your current humidity?

I'm not skilled enough to go by air cell size when I candle, if I see veins at day 7 I'm happy.
You can keep your humidity a little higher to help prevent them drying down too much but I would candle a few eggs every three days to monitor their status. I find it is easier to speed up derying than to slow it down.

If the air cells are larger than expected, raise humidity a bit. If smaller than expected, decrease humidity. It's all about the amount of moisture in the air and how that allows the egg moisture to evaporate. Higher humidity = slower evaporation and vise versa.
What Lisa said ..... and in future ...

You might want to try weight loss techniques. No, I'm not being personal
I mean the eggs.

Chicken eggs should lose between 11 and 13% of their setting weight by day 18.

If they are losing too much, raise the humidity, and vice ... you get the drift.

With valuable eggs this matters. Eggshells vary in thickness, and ideal RH for one might not suit another.

In any event it's a great project to get kids involved in, they can draw charts and all sorts of interesting stuff.
Thanks to all - I am going to increase the humidity and next time I going to attempt "watching my weights"
- - I agree that would be a great 4H project -our kids are out of the house but I have nieces and nephews interested.

I use a forced air hova-bator - but wasn't smart enough to check the factory temp setting to be sure it was set right - after shattering my nerves through day1 I bought new thermometer w/more accurate temp & humdity - as it turned out my incubator was set wrong - one switch too high -

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