Although there are several different styles of candy thermometers, most cooks like the rectangular metal ones with the thermometer encased in the metal frame. With this design, the thermometer bulb will not touch the bottom of the pan even if you rest the thermometer in the pan.
Some cooks say you will have better results with candy if you don't make it on a rainy day, when air pressure is low.
1. Do a test to be sure your thermometer is accurate. Let it stand in boiling water for 10 minutes. If the thermometer doesn't read 212 degrees F, you need to figure the difference and add or subtract to make the temperature measurements correct for your candy.
2. Gather the ingredients for your candy recipe.
3. Follow the recipe as directed until you get to the cooking stage.
4. Cook the candy as directed. Some recipes will give you a temperature to aim for, while others may use one of the following terms: "thread," "soft ball," "medium ball," "firm ball," "hard ball," "very hard ball," "light (or soft) crack," "hard crack" or "caramelized sugar" stages. The temperatures for some or most of these terms should be indicated on your candy thermometer.
5. Place the candy thermometer in the pan with the cooking candy. Be sure the bulb of the thermometer never touches the bottom of the pan, or the temperature will register too high. You want to find out the temperature of the candy mixture, not of the pan.
6. Continue to cook the candy until it reaches the desired temperature.
7. Remove the candy thermometer (be careful -- it will be hot) and follow the recipe to complete the candy making.
Warning: Children should be closely supervised when around hot pans or boiling candy mixtures.