As I was reaching for my candy thermometer a few days ago, while making marshmallows, it dawned on me I hadn’t used it in ages and, while cooking the sugar, I observed it was taking longer than my instincts felt was right. I should have calibrated the thermometer before using it.
If you hardly ever use yours and it sits at the bottom of a drawer or, conversely, if you use a meat thermometer often, every time you cook a bird or a roast, it’s a good practice to test your thermometer on occasion. Like ovens, thermometers lose a few degrees of calibration if left unchecked.
There are two simple ways you can do it:
- The ice-point method. Place the thermometer in the centre of a container filled with water and ice. The temperature should register 32F (0C).
- The boiling method (the only one you can use for candy thermometers). Place the thermometer in the center of a container filled with boiling water – it should read 212F (100C).
If the thermometer is off by a few degrees, assuming you are holding a probe one, you can re-set it by keeping it in the liquid while adjusting the probe underneath the head (you might need pliers or hook the thermometer to its cover and twist). If you have a flat glass thermometer (many candy ones are that way) there is nothing you can do but take into consideration the difference in degrees while you are using it.