Candling refers to two very different practices: shining a light through an egg to inspect its contents, or placing a hollow, lit cone in the ear as an alternative health treatment. Egg candling is a widely used technique in poultry farming and egg production, while ear candling is a controversial practice that major medical organizations warn against. Which one you’re looking for depends on context, so here’s what you need to know about both.
Egg Candling: How Light Reveals What’s Inside
Egg candling is the process of holding a bright light against an eggshell to see what’s happening inside. The shell becomes translucent enough to reveal cracks, blood spots, signs of fertility, and embryo development. The name comes from the original method: holding eggs up to a candle flame. Today, high-intensity LED lights do the job far more effectively.
There are two main reasons people candle eggs. Backyard poultry keepers and hatcheries candle during incubation to track whether embryos are developing normally and to remove eggs that aren’t viable. Commercial egg packers candle table eggs before they reach grocery store shelves, checking for hairline cracks, blood spots, meat spots, and other defects that would lower the egg’s grade. Under USDA standards, eggs with large blood spots, bloody whites, or leaking contents are classified as inedible and pulled from the supply chain. Small blood spots (no larger than 1/8 inch) can still qualify as Grade B.
What You See When Candling During Incubation
If you’re hatching eggs at home, candling gives you a window into whether things are progressing normally. The visual changes are dramatic over the course of a 21-day chicken incubation.
During the first week, a fertile egg shows thin red veins spreading outward from a small dark spot, which is the embryo. The air cell at the wide end of the egg is small and clearly visible. An infertile egg, by contrast, looks uniformly clear with no veins at all. This first candling around day 7 is the most important one, because it tells you which eggs to keep incubating and which to remove.
Between days 8 and 14, the embryo grows substantially. You’ll see a larger dark mass, blood vessels covering more of the shell’s interior, and visible movement. The egg gets noticeably darker with each passing day as the chick takes up more space. By days 15 through 18, a healthy egg is almost entirely dark, with just a large air cell visible at the top and occasional movement inside.
Dead embryos leave telltale signs. A blood ring, a distinct red circle inside the egg, means the embryo died early. Eggs with no veins and no growth after a week are infertile. Late-stage deaths produce eggs that look dark but show no movement at all. Removing these non-viable eggs matters because rotten eggs can explode inside an incubator, contaminating the healthy ones.
Choosing the Right Candling Light
Any bright, focused light source works for candling, but some are better than others. Research comparing different LED colors found that warm white LEDs achieved the best accuracy for detecting fertility, correctly identifying 94.9% of eggs by day 7 of incubation. Dark-shelled eggs (like those from Marans or Barnevelders) absorb more light and are harder to read, so a stronger light source helps. Dedicated egg candling lights are inexpensive and widely available, though a bright LED flashlight held flush against the shell works in a pinch.
Before you start incubating, candling eggs lets you check for hairline cracks in the shell. Even tiny cracks allow bacteria to enter during incubation, which can kill a developing embryo or lead to contamination.
Ear Candling: What It Claims to Do
Ear candling is an entirely different practice. It involves a narrow, hollow cone made of fabric soaked in beeswax or paraffin, which has been allowed to harden. During the procedure, a person lies on their side while someone inserts the tapered end of the cone into their ear canal. The wide end is lit on fire and left to burn for several minutes.
Proponents claim the burning candle creates warmth and suction that draws earwax out of the ear canal. After the session, there’s typically a waxy residue left inside the cone, which practitioners present as extracted earwax. The practice has also been promoted as a treatment for sinus infections, sinus pressure, earaches, vertigo, and even cancer.
Why Ear Candling Doesn’t Work
None of these claims hold up to testing. Measurements conducted during controlled studies showed that ear candles do not produce negative pressure inside the ear canal. No vacuum forms, and no suction pulls wax upward. The waxy residue left inside the cone after burning is from the candle itself, not from the ear.
The American Academy of Otolaryngology states plainly: “There is no evidence that ear candles remove impacted cerumen, and candling can cause serious damage to the ear canal and eardrum.” Rather than clearing earwax, the process can actually deposit candle wax into the ear canal, making blockages worse.
Risks of Ear Candling
Beyond being ineffective, ear candling carries real physical risks. You’re holding an open flame inches from your face and hair, directed into a sensitive body part. Reported injuries include burns to the face, ear canal, and outer ear, as well as perforated eardrums and candle wax deposits that require medical removal. Health Canada and the FDA have both issued warnings against the practice.
If you’re dealing with excess earwax or a blocked ear, safer options exist. Over-the-counter ear drops designed to soften wax, irrigation kits, and professional removal by a healthcare provider all have track records that ear candling does not.