When making candy a variance of just a few degrees can result in burnt candy. Candy thermometers should be tested for accuracy frequently. To test your candy thermometer, bring a pot of water to a boil. Insert your candy thermometer and leave it for a few minutes. If your thermometer reads 212 degrees Fahrenheit then it is accurate. If your thermometer reads above or below this you will need to adjust the temperature you cook your candy to. For example, if your thermometer read 205 you would need to cook the honeycomb to 307 degrees Farenheight rather than 300.