Hard-Crack Stage refers to a specific temperature range when cooking sugar syrups. Hard-Crack Stage occurs at 300-310 degrees. This stage can be determined by dropping a spoonful of hot syrup into a bowl of very cold water. Remove the candy from the water and attempt to bend it. If hard-crack stage has been reached, the syrup will form brittle threads in the water, and will crack if you try to mold it.