Sugar syrup becomes candy, ranging from fudge to lollipops, in stages depending on its temperature, making candy thermometers convenient -- but not indispensable. Candy also indicates its development by how it reacts when dropped in cold water. As candy gets far hotter than boiling water and causes severe burns, exercise caution. Keep a large bowl of ice water close to dip your hand in if needed.
You need a couple of glasses of chilled water, a spoon, the candy mold, a timer or clock, and a pastry brush in a bowl of water at your work station before you start melting the sugar. Chill the glasses of water in the freezer for 15 minutes, then keep them in the refrigerator until you need them.
Readying the Sugar
Pour the sugar needed for your recipe in a heavy-bottomed saucepan; then add a few extra spoonsful, as you'll need extra for your tests. You should use a saucepan wide enough so the sugar isn't less than 1/4 inch deep. It takes longer to cook 1/4 to 1/2 inch of sugar than it takes to cook 1/4 inch or less sugar, and you need the extra few seconds it allows to check its progress when you don't use a thermometer.
Melting the Sugar
Set the sugar over medium heat and cook it until the edges melt, then slide the pan back and forth quickly. Stir the sugar with a spoon and wipe the inside walls of the saucepan with the wet pastry brush. As the sugar cooks, wipe the sides of the saucepan with the wet brush every couple of minutes.
Soft- and Firm-Ball Stages
Check for the soft- or firm-ball stages after the sugar cooks for 3 minutes if you're using the candy for fudge, fondant or Italian meringue. Spoon about 1/2 teaspoon of sugar from the pan and drop it in the water then place it in your hand. If the sugar flattens in your hand after a couple seconds, it's at the soft-ball stage; if the ball of sugar doesn't flatten on its own, but still feels malleable, it's reached the firm-ball stage.
Hard-Ball and Soft-Crack Stages
Check for the hard-ball and soft-crack stages after 4 to 5 minutes of cooking. Use sugar cooked to the hard-ball stage for marshmallows and gummies and sugar cooked to the soft-crack stage for taffy and butterscotch. Hard-ball sugar forms a hard ball you you have to press hard to compress; soft-crack sugar hardens into threads when drop it in the water. When you take the threads out, they bend a little before breaking.
Hard-Crack and Caramel
Check for hard-crack and caramel after 6 to 8 minutes of cooking. Hard-crack sugar, used for lollipops, forms threads in cold water that break without bending; this is as much as sugar cooks before caramelizing. Cook sugar for about 10 minutes after it melts, or until it reaches the desired color, to make caramel.