You can beat egg whites using a standing mixer, a hand mixer, or a whisk. Some chefs even use multiple whisks when doing it by hand to speed up the process.
How to prepare your egg whites
Egg temperature: It is easier to separate the egg whites from the yolks when they are cold and right out of the refrigerator. However, eggs whip up better when they are a bit warmer, so after you’ve separated them, let them come to room temperature by leaving them on the counter for 15-20 minutes before whipping.
Separating your whites and yolks (see article on cracking and separating eggs): Egg whites don’t like fat, so make sure you carefully separate your egg whites from the yolks and not to get any yolk into the whites.
Preparing the bowl you will be whisking in: Use a glass, metal, or copper bowl to whip egg whites. Wipe down your mixing bowl well to make sure there isn’t any residual fat from previous uses.
Consider using a stabilizing agent: A small amount of acid, such as cream of tartar, lemon juice, or vinegar can act as a stabilizing agent and help the egg whites hold their fluffiness. If you are using a copper bowl, you don’t need to add a stabilizing agent.
Add sugar after you’ve started whipping: Your egg whites should reach the foamy stage before you begin adding sugar to the mix. Add a little at a time to let the sugar fully incorporate. To check if the sugar has dissolved fully, rub a bit of the meringue between your fingers and feel if it is smooth or sandy. If it is sandy, that means the sugar hasn’t yet dissolved.
How to beat your egg whites
You can beat egg whites to several consistencies - foamy, ribbon stage, soft peaks, firm peaks, and stiff peaks.
The foamy stage is when the egg whites start to foam up with a lot of bubbles and have doubled in volume. It is at this point that you want to add any sugar if you are adding sugar to the mix.
Ribbon stage is when the mixture becomes thick and pale but still very runny. When you lift the mixture with the whisk, it should fall like ribbons that lay on the surface of the mixture of a few moments and then blend back in.
Soft peaks barely hold their shape and peaks flop over when the whisk is pulled from the mixture and held upside down.
Firm peaks hold their shape pretty well but the tip will still curl down when the beaters are lifted out and held upside down.
Stiff peaks will point straight up without collapsing when the whisk is held upside down, you can even hold the bowl upside down over your head and nothing will drip out.
How to troubleshoot egg white issues
If you’ve over beaten your egg whites, they will look clumpy. You can save the mixture by just adding another egg white to the mix and whipping it in. This should make the mixture smooth again, and be careful not to over whip again.
If your egg whites just aren’t whipping up, it likely means that they were exposed to some fat, either a bit of yolk that got into the mix, or some residual fat (oil or butter) that may have been left on the mixing bowl. You will likely need to start over with a fresh set of egg whites.