If the fondue is too thin, some add cornstarch mixed with white wine, others add more grated cheese. If, on the contrary, it is too thick, add white wine. If it curdles, or appears to be broken, bring to a boil it, whisking vigorously with a dash of lemon juice.
When the fondue has been eaten, there will be a golden crust at the bottom of the pot. It's the “religieuse”. It was named so in honor of the nuns who wore several layers of clothing, called “crusts”. Fondue connoisseurs fight to eat the “religieuse”. Remove it gently and wait one minute, time for it to becomes slightly crispy. A delight!