Not washing and storing eggs with the rounded end up will prolong their shelf-life.
Why? How? The answers are simpler than you may expect.
Why not washing eggs is good for them…..
When the chicken lays the egg it is coated with a substance called “bloom” which seals the shell. The shell is porous and washing it removes this protective coating which permits bacteria to enter into the egg.
It is best to avoid washing eggs, but there are times when they do require a bit of cleaning. At those times it is best to flick off any dried on bits, or
gently spot clean with a moistened cloth.
The cycle of an egg is quite amazing. It begins as a yolk, one of many, which are stored deep inside the hen. During each 24 hour period the yolk travels from the ovary developing the white and finally the shell before being expelled through the vent. Just before it is laid, it is coated with the bloom.
Inside the eggshell there is a small pocket of air which is for the chick. Over time, since the shell is porous, more air enters into the egg. The bloom slows this process.
When the egg is stored pointed side down, the air pocket is located at the top rounded end between the inner and outer shell membranes. then This pocket gradually grows over time as the egg loses moisture. Keeping the air pocket at the top helps to prevent it from rupturing and reduces the risk of spoilage. It also helps to keep the yolk centered in the white.