Photo from Carla Emery’s book The Encyclopedia of Country Living.
When incubating eggs, or when a hen is sitting on a clutch, there is a way to find out whether or not a chick is actually growing in there. This process is called “candling”. Long ago, it was actually done using candles, but nowadays there are many different ways to do it. You can buy special candling equipment, or simply rig something yourself. The idea is to shine a very bright light through the eggshell in a dark room, which illuminates the shell and allows you to see what’s going on inside!
Tonight, we candled our 15 eggs. What we used was very basic- a desk lamp and a small box. In the top of the box we cut a hole, just big enough that the egg could barely sit down in it without falling through. We laid the lamp down on a table, and put the box over the light bulb. With all other lights off, we put each egg, one by one, over the light shining through the hole in the box.
You guys, this is so exciting! It’s almost as good as seeing a sonogram!! The light shines through the eggshell, and if it’s fertile, you will see a little chick growing (and moving!) inside!! I squealed with excitement when I saw that first little chick moving within its shell.
After 72 hours of incubating, you should be able to easily distinguish between fertile and non-fertile eggs. The good ones will have spider-like blood vessels spreading within (see picture above). It’s best to candle early on; if you have an egg that is obviously not fertile, it is still safe to eat after being incubated for up to nine days.
I wish we would have candled our eggs sooner though. Ours have been incubating for two weeks now, so the chicks are quite developed. Once the chicks are so far along, they appear to be a large dark mass within the shell. Some of mine moved, so it was easy to tell that a chick was alive in there. But others just looked like a dark shadow. I’ve had a very hard time distinguishing between good eggs and bad ones. It wouldn’t be such a big deal to just leave them alone, but I read that the bad ones can rot and actually explode- spreading bad bacteria all over the other eggs, and making a big, stinky mess in the incubator!! So I definitely want to get the infertile ones out.
There are some eggs that I think are bad, but dang, I’d hate to throw one out if it’s actually alive!! I’m gonna have to candle them again and really take a close look to determine whether they are in fact growing or not.
Any experienced “candlers” out there who can give me some help with this? How can I tell if the dark mass inside the shell is alive or not if I don’t see it moving?