How to use an Egg Candler

Do you want to know how to use an egg candler? If so, this article is meant for you. Farmers usually use an egg candler, which is a device that is used for testing eggs from backyard chickens during the incubation period, to check if the eggs are viable or not.

A viable egg is the one that has already been fertilized, and an embryo is capable of growing inside and hatching. Nowadays, light bulbs are used for egg candling by directing the light inside the egg to see if the egg is developing into a chick, and one of you essential tools if you want to hatch chicks.

Candling only shows if an egg is viable on the fourth day after incubation when the blood veins of the embryo start to develop.

There are various steps to follow while using the egg Candler, and this includes:



Setting the candling equipment in an appropriate position at proximity to the incubator.



Hold the eggs and place them with the larger side of the egg (air sac side) facing the light. Ensure you tilt the egg to all the sides until you have a clear view.



Mark each egg with a different number so that you can compare your results after the second candling process.



Check if the eggs are viable or not viable. This can be done by observing blood vessels that tend to spread from the center of the egg towards the outside. With a good light source, you may also be able to see the embryo outline at the center of the egg or even see the embryo moving if you are lucky enough. Check also if the egg is not viable. You can use an egg Candler to see whether an egg is not viable, this is by observing the development of a blood ring or blood spot inside the egg.



Discard the non-viable eggs to prevent them from exploding or going bad inside the incubator.



Gently place the eggs back to the incubator or nest after observing them. Ensure you don’t keep the eggs from the incubator for more than 20-30 minutes.


Some eggs can also be Yorker that is, an egg that was not fertilized and thus cannot develop an embryo. The inside of the eggs has no blood vessels, blood spots, or even dark spots; it is just clear. It’s thus important for you to clearly and carefully observe the eggs. It’s advice if one is not sure whether the eggs are a Yorker or not viable to leave them and keep observing. It’s difficult to candle speckled or brown eggs since they do not become transparent under the light; thus, a high-intensity light is required.