Special Techniques & Reference Section
A Guide to Candy Cooking Stages (Temps)
While most thermometers offer an inkling or list of various stages in cooking different types of candy, not all do and few offer the ranges of cooking temps within these stages.
Stage Target Temp Fahrenheit Target Temp Celsius
Jelly 220 104
Syrup 230 110
Fudge 235-237 115
Soft Ball 240 116
Firm Ball 250 121
Hard Ball 260 127
Soft Crack 280 138
Hard Crack 300 149
How to Calibrate Your Candy Thermometer
In candymaking especially, the first most important item to ensure your success is in using a calibrated thermometer. And not one single model you ever will buy will be calibrated. I know, as I’ve bought probably 30 over the years, from the old-fashioned models to digitals to even lasers. It’s just the nature of the beast, since thermometers are made in one place (often China) and we use them in another, usually at a different altitude and climate.
Calibrating a candy thermometer is typically done using the boiling water method below and it is a good enough method to ensure candy accuracy. Extreme calibration used by A/C contractors and other industries that require absolute temps depends upon consideration of altitude and barometric pressure, but the following method will allow you to basically calibrate your thermometer regardless of altitude and barometer readings.
Fill a large saucepan with water to two inches from the top. Bring the water to a full rolling boil, then attach/insert your thermometer. After ten minutes in the boiling water, take a reading from your thermometer.
If your thermometer reads 212-degrees (F), rejoice – not only are you exceptionally lucky, but you can rely upon it to accurately read your temperatures in cooking.
If your thermometer registers any heat other than 212-degrees (F), you will need to subtract or add degrees to compensate.
For example, if your thermometer registers 210-degrees (F) after boiling in water for ten minutes and you are cooking a fudge to 235 degrees, you must add two degrees to the final cooking temp on that thermometer (i.e., keep cooking until 237 degrees).
Also for example, if your thermometer registers 215 degrees after boiling in water for ten minutes and you are cooking that same fudge to 235 degrees, you must subtract three degrees from the final cooking temp on that thermometer (i.e., stop cooking at 232 degrees).
TIP: As I have several different thermometers I like to use in different pots, etc., long ago I learned to write the temperature differential in indelible ink on the top. One thermometer will be enscribed “+2” and another “+1” and another “-3” and so on.
TIP: If you are using an infrared laser thermometer, you need not stand there for ten minutes aiming the light at that boiling water. Simply aim the laser for 6 to 10 seconds. Most lasers are “guaranteed” to plus-or-minus one degree, but trust me when I tell you it is very important to verify that. I’ve not yet found one closer than 2 degrees in accuracy.
TIP: Make certain the bottom of your thermometer is NOT resting on the bottom of the pot when calibrating OR cooking. This is especially the case for metal-encased rectangular models. In these, the bulb will certainly never touch the pot bottom, but the metal surrounding it will and absorb too much heat. That’s one reason why I don’t use this type…