The speed of whisk, length of time whisking, cleanliness of egg (i.e. no yolk), state of the bowl (e.g. needs to be clean and dry) etc.

Factors affecting the stability of Meringues are as follows:

1. Only absolutely clean and dry bowls preferably ceramic, glass or stainless steel to be used for making meringues.
2. Fat inhibits foaming.
3. Mild acid like lemon juice or cream of tartar helps to foam.
4. Egg whites foam better at room temperature.
5. Do not overbeat egg whites for they will look dry and curdled.
6. Sugar makes the foam stable, but it can also cause weeping because of the absorption of water.