A bakery proofer is a piece of equipment that warms the air around yeast dough, allowing it to rise at the proper temperature. The temperature must be warm enough to encourage fermentation, yet cool enough that the dough does not bake. This temperature range is typically 70-115 degrees Fahrenheit. A proofer also maintains proper humidity. A proofer can be used for the first rise of dough, known as bulk fermentation, or the final rise.