I never thought much about cracking eggs, since I’ve never used a recipe where I needed to separate the yolk from the white.
INFORMATION BELOW FROM 1800s COOKBOOKS:
TO SEE THAT EGGS ARE GOOD
Whenever you break eggs, never mind what quantity, always break each egg separately into a cup first. See that it is good, and then throw it into a basin with the rest. One bad egg would spoil fifty. Supposing you have a dozen or two dozen new-laid eggs just taken from the nest. It is not an uncommon thing to have one that has been overlooked for weeks, and which may be a half-hatched mass of putrefaction.
BREAKING OF EGGS
In cookery, it is usually desirable to break an egg shell so that the yolk will not run into the white. A quick method consists in striking the shell on the edge of the pan or the bowl into which the contents are to be put. A preferable method consists in striking one side of the shell a sharp blow with the edge of a knife, midway between the ends. The advantage of this method will be evident after a trial or two, for it will be found that the depth of the cut made by the knife can be so gauged that there will be little danger of breaking the yolk. Besides, fragments of the shell are not likely to fall into the bowl or the pan with the contents of the egg.
SEPARATING OF EGGS
Frequently recipes require that the yolks and whites of eggs be beaten separately before being added to the other ingredients. When this is the case, care must be exercised in taking the egg from the shell. Strike the egg one blow upon the surface of the table. Put the thumbs together at the crack in the shell, then hold the egg upright, and gently break the shell into two parts. As will be observed, the shell is first broken as nearly as possible into halves and then, while the egg is poured from one-half of the shell into the other, the white is dropped into a dish and the yolk is retained in the shell. During this process, the yolk should remain intact in its delicate membrane, for if it becomes mixed with the white, the lightness of the white will be injured. To separate the yolk from the white is not difficult when eggs are fresh, but as they become stale, the membrane surrounding the yolk grows weak and breaks easily. If the yolk breaks and any of it falls into the white, it must be completely removed before the white is beaten.
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BREAKING AN EGG WITH ONE HAND
The trick of breaking an egg with one hand is something that you should learn how to do. It not only gives you speed, but shows that you are a workman thoroughly familiar with your business. The trick can be acquired with a little practice. To do it nicely, the hand should be a little moist. Hold the egg in the right hand between the forefinger and the second finger with the thumb on top. Strike the egg once sharply on the rim of the glass to crack the shell, then holding it over the glass press down slightly with the thumb and the egg drops out, leaving the shell in the hand. While learning to do this the glass should be allowed to stand on the counter, so that if you fail, the left hand can come to the assistance of the right. Just as soon as you know that you can break the egg with one hand, then you can hold the glass in the other. This saves time, especially when you have two or three to prepare at once. When you have become proficient with the right hand, try the left until you can use either or both.
Can You Crack an Egg With One Hand?