2 cups water
4 cups sugar
food coloring (optional)
up to 1 tsp flavoring (optional)
cut the baker's twine to desired length. tie the twine off to a wooden skewer or pencil. this will allow you to suspend it in the syrup. Dip the twine in water, then roll in a bit of granulated sugar to coat. allow to dry while you make the syrup.
bring water and 1 cup of sugar to a simmer in a saucepan. while the water is still simmering, add sugar, 1 cup at a time, stirring and ensuring the sugar has completely dissolved before adding the next cup. once all sugar is incorporated, remove from heat and add coloring and flavoring. allow the syrup to cool slightly, then pour into a clean and sterilized glass jar or tall glass. you will need a separate glass for each rock candy you want to make.
suspend the twine in the syrup being careful that it does not touch the bottom or sides of glass. crystals should begin to form in about 4 hours. if there is no activity within 24 hours remove the twine, pour the syrup back into a pot and heat to a simmer. return to the clean and sterilized jar and start again. if you see excessive crystallization on the sides of the jar or glass, remove the twine and perform the above steps, otherwise you will have a glass full of hard sugar crystals.
check your twine daily. when you have the rock candy of your desire, remove from the syrup and allow to hang dry for a few hours.