How to Candle Duck Eggs
Candling uses a bright light in a dark room to observe veins, embryo development, air-cell growth, and eggs that may have stopped developing.
When to Candle
Candle in a dark room with a bright cool light, keeping the egg out of the incubator only briefly. Veins and a darkening embryo should develop over time; a clear egg or blood ring may indicate failure, but uncertain eggs deserve a later recheck.
Safe Handling and Duration
Wash and dry hands, support the egg, and keep it out of the incubator only long enough to view the contents. Do not rotate forcefully.
Use a cool LED light and return the egg in the same orientation. Cracked, leaking, or foul-smelling eggs should be isolated.
Normal Development Signs
Developing eggs show branching veins, an embryo, movement, progressive darkening, and a growing air cell. Visibility varies with shell color and thickness.
Compare photographs only as a guide; incubation day and the individual egg matter. Mark observations for the next candle.
Clear and Questionable Eggs
Egg output is shaped by breed, strain, age, daylight, molt, nutrition, stress, and health. Track each flock over time instead of treating a published annual figure as a guarantee.
Late-Incubation Limits
Successful duck-egg incubation depends on stable temperature, clean handling, regular turning before lockdown, and an accurate calendar. Record readings and changes so a problem can be traced rather than guessed.