It is possible to successfully incubate a cracked if you can reseal it quickly to prevent bacteria getting inside. There is a limit as to how much damage you can repair when it comes to egg shells and if the membranes are damaged the chance of failure is much higher.
Expect a success rate of 30 to 40% with repaired eggs. Methods to fix eggs are below.
In the past I have Incubated cracked eggs with varying levels of success. I always check my egg with a candling lamp before setting them but I have cracked egg during incubation.
Will a cracked hatching egg survive in the incubator?
Some cracked eggs may survive the 21 days in the incubator, it depends how bad the damage is, whether the membranes are torn and how close to hatching it happens.
I would not incubate a cracked egg from day 1. If you crack one during incubation then try repairing the egg and give it a go.
Bacteria could easily enter through that crack and cause a rotten egg. Also moisture may evaporate faster than it would normally from an egg in the incubator so the embryo may dry out too much to hatch.
Below: The cracks in an egg showing up with a candling lamp.
If the shell's inner membrane isn't damaged it stands a much better chance of surviving.
When should you try to incubate or save a cracked hatching egg?
If you have eggs from expensive, rare or endangered breeds then you might want to try. Eggs that have been in the incubator for a week or two are more likely to finish successfully as well.
If you do receive a cracked egg in posted hatching eggs and it’s an expensive or rare then you can try to hatch it, but beware of bacterial explosion and the good possibility of ruining other eggs. It is possible to hatch a cracked egg by sealing the crack with candle wax/crayon wax or finger nail polish. Try to place the egg in a cup or protected place well away from other eggs.
Can I incubate a cracked or broken egg?
You should never set a cracked egg in an incubator, the chances of it going bad and exploding are very high and it could ruin the complete hatch.
I would cook the cracked one and feed it to chickens or toss it. It would probably explode and smell horrible in the incubator.
Below: Small cracks stand a much better chance of surviving incubation.
When I lost a rooster from a breeding flock I had one that was cracked. I repaired it with tissue and superglue and surprisingly it hatched. It’s possible to hatch them out but it’s risky.
Always keep cracked egg separated from the others if you do try .
If the egg stays viable and begins to hatch, keep a close eye on where the pip mark will be in case the chick can't get through a fixed area or struggles with the wax.
What special precautions do you need to take when incubating cracked hatching eggs?
Just the one, candle and check daily and discard at the first sign of problems, smell or infection.
You can also keep them in a small plastic dish in case they leak.
Do eggs crack in the incubator?
Eggs with weak shells can crack in incubators with certain types of automatic egg rollers or if you hand turn eggs and are too rough with them.
It should be noted that calcium from the shell is used by the chick during incubation and the shells get weaker as incubation progresses.
How to repair and save cracked hatching eggs:
- Act quickly.
- Candle to make sure the embryo is still alive and moving, there's no point in trying to save a dead egg.
- Repair the egg with your chosen method.
You can use one of the following methods to repair cracked eggs in the incubator:
- Use beeswax or unscented candle wax to cover the crack. Drip it straight from the burning candle or melt a little and add drop wise with a spoon.
- Use Tissue paper and superglue to make a solid and airtight seal on the egg.
- Nail polish. Plain clear nail polish is best but I have seen pink used successfully.
Don't use a wax polish at this has various other organic solvents that can kill and injure chicks.
Below: An egg repaired with candle wax.
Don't use porous materials like band aids, plasters or wound tape to fix eggs as they won't provide a barrier. Also it is very difficult to get flat tape to cover the crack properly without folding or ridges, both a which will allow bacteria in and moisture out.
Scotch tape will not work because of the heat and moisture.
Below: The wrinkles in the tape and the susceptibility of the glue to moisture means tape is likely to fail.
Put some candle wax or Bees wax. Light candle, let it drip on the crack.. Unscented is best. I’ve done it and babies have hatched. I also use the candle wax if I accidentally crack someone while candling.I have heard of people using a fine line of wax.
Will cracked and repaired eggs still hatch?
You would think that it would be easier to hatch if the shell is already broken and this may be the case. Chicks hatching from repaired shells almost always need a hand of some sort to get out .
Below: Eggs damaged like this will almost always never hatch.
I decided to do the tissue paper and superglue glue patch. I took a piece larger than the hole, placed it over the hole and applied a thin layer of glue. Superglue can be used in place of stitches to hold a cut or wound closed.
Below: This is the egg with the hole before the repair.
Below: This is the egg with the Superglue and tissue repair.
It's not so much a crack as a hole. It got damaged from the outside but the inner membrane is torn but the chick is moving.
I candled to check if baby was still alive. I repaired it and put it back in the incubator last night.
This chick went on to hatch just fine without any help a few days later.