From the first stage of being a simple syrup to the last stage when it becomes a caramel, sugar passes through six distinct stages of cooking which are known as: the small thread 103 °C (218 °F), the large thread 107 °C (225 °F), the soft ball 115 °C (240 °F), the hard ball 121 °C (250 °F), the soft crack 141 °C (285 °F), the hard crack 157 °C (315 °F) and caramel 182 °C (360 °F).
Method: Place the required amount of sugar in a very clean copper pan with 1 tbs glucose per 500 g (1 lb 2 oz) sugar; add just sufficient water to ensure that the sugar dissolves. Bring it to the boil, and skim carefully; any impurities in the sugar could cause the sugar to crystallize later on.