You can drop your hard-boiled egg in and it will sink to the bottom of the first layer, but float on top of the salt water! The egg is denser than tap water, so it sinks. Adding salt water to the water makes the water denser than the egg. This causes the egg to float!

Do boiled eggs float when done?

No. Old eggs tend to float, whether raw or boiled, as they have lost moisture and their density has decreased. Fresh eggs sink in water, whether raw or hard boiled. ... If it is cracked, but still has substance inside, then it's boiled or cooked.

Why are my eggs floating when boiling?

Why Do Cracked Eggs Float? If the egg's shell is cracked, egg white will leak out into the boiling water. This reduces the mass of the egg, making it easier for the less-dense egg to float. Some bits of boiled egg white will float around in the saucepan of boiling water, which is unattractive but harmless.