What does the salt do to stop the shell from cracking?
(((HUMOUR REPLY)))
I’ll tell you the whole story: Salt and shell one fine day discovered each other sitting side by side on the refrigerator shelf. “Well, hello, but what are YOU doing here?” Shell pleasently asked Salt. After all, it isnn’t every day that one finds salt sitting beside one in the refrigerator. No-sirree-bob-itaint! “I 'on’know, but it’s cool here,” answered Salt in his usual way of speaking without a lot of spicy words. Well, Salt and Shell became loyal friends, indeed-ee-dee, yes-siree-bob-now-surely-they-did, them two there sitting together on that refrigerating shelf. One day, doncha know tho, while salt and shell were confiding in each other, as friends often do, shell was swept up into Big Hand, leaving salt sitting alone and so sad on the frigid shelf. That was certainly bad enough, but the further matter happened anyway: Suddenly, Big Mouth shouted directly at shell, “NOW WHERE’S MY SALT! WHERE’S THAT SALT! I’M READY T’GETTA HOLDA THAT SALT SO I CAN SHAKE IT ALL OVER THIS SILLY SHELL BEFORE I EAT BOTH, AND WHERE IN TH’FLAMM IS THAT SALT!! IF YOU DON’T TELL ME I BET I EAT WITH NO SALT AT ALL, THAT’S JUST WHAT I’LL DO, TOO” Well, now, lemmee tell yer. Shell almost cracked. But it looked fretfully at salt and salt said, “It’s alright Shell, I know that big mouth. I been livin’ here weeks before you showed up. That big mouth ain’t gone each you if it cain’t salt you. You just hold yerself together there!” Sure 'nuff, Big Mouth done told Big Hand t’put Shell back in that refrigerator 'cause Salt was NOT to be found in the pantry anytime soon. And when Shell and Salt were back together on that refrigerator shelf, Hand shut the fidgetated door, cooperating without a clue… And since Big Mouth and Big Hand are lead by a bigger Tiny Intellect, Shell and Salt remained living together uninterrupted in that refrigerator for an awfully long time. ((What made it so awful, doncha know, is the pound of spinich, you know, 'cuz aftabout a monff or so, doncha know, it begin to git a might powerful odorful! Y’all come on ov’fo’dinner now, right aftuh brekfast, y’hearz!!
Shell and Salt©ASPA2000
Shell and Salt © ASPA 2000
Personally, I have never noticed salted water making any difference to whether the shells crack or not.
What does work for me is to let the eggs warm up to room temperature first. Then I put the eggs into a pot of cool water before placing them on the stove.
The technique that yeilds the most cracked shells seems to be the, “drop the eggs straight from the fridge into a pot of boiling water” method.
Evil: You’ll get the same results by placing them in warm to “early hot” water (after leaving at room temperature); it has the added advantage of saving a few minutes’ cooking time.
Doesn’t salt allow water to boil at a lower temperature, the same way it allows ice or snow to be melted at a lower temperature?
I don’t know what that has to do with the shells not cracking, though.
This thread has some info about raising the boiling point of water with salt:
http://boards.straightdope.com/ubb/Forum3/HTML/005148.html
“No,” he replied, and smiled seraphically, as was his wont.
Some interesting points here.
Take a needle, or a push pin, something like that, and poke a small hole in the fat end. Then boil as usual.
Drain the hot water, shake the eggs in the pot to crack them, then add cold water and let them sit till cool.
Peel the eggs under water.
You’re welcome. 
Peace,
mangeorge
Mangeorge,
But what if you are going to color them for Easter?
If you’re going to color them for Easter, gently put the eggs in an empty pan, then add water from the tap. Put the pan with eggs and water on the stove, and turn up the heat, bringing the water to a boil. As soon as the water boils, remove the pan from the heat, put a lid on it, and let it sit quietly for 20 minutes. Then, remove the lid, drain the water and let the eggs cool. You should have pretty yellow boiled yolks, and no cracked shells. (At least that’s how it works for me.)
A ship in the harbor is safe, but that isn’t what a ship is built for.
Going back to the OP…salt does not keep the eggshell from cracking.
It causes the escaping white of the egg to set quickly, which seals up the crack.
Easy. Soft boil them, peel them, color them, then hide them. Should be fun to watch. 
Peace,
mangeorge