Checking the calibration of your thermometer is a critical task that should be done on a regular basis.  Follow these steps:

1.  Gather an insulated container such as our model 9325 Val Cup, approximately 3 cups of crushed or shaved ice and your thermometer.  Note that crushed or shaved ice is essential.  Large chunks (or cubes) of ice will not give you accurate results.

2.  Fill the insulated container approximately 3/4 full of the crushed or shaved ice.

3.  Slowly add cool or cold, clean water to the ice.  Stop adding water when the water is approximately 1/2" below the top level of the ice.  The key is to be sure the cup contains a slushy mixture of ice water.  If your ice is floating at all (i.e. - if there is water at the bottom of the container without ice) the results will not be accurate.

4.  Stir the mixture to break up any ice that may be sticking together.

5.  Insert your thermometer into the slush mixture and stir it around until the reading stabilizes.  Your thermometer should now be displaying a reading of 32 Degrees F (0 Degrees C), +/- 0.2 or 0.3 degrees or to be within the specified accuracy of the thermometer. 

6.  In the event your thermometer does not read as it should, it can usually be calibrated.  The small dial types can usually be calibrated by the user by holding the nut on the back of the head with a pair of pliers while the stem is still in the slush, then turning the head of the thermometer until the pointer dial is directly at 32 degrees.  Other types of thermometers (there are too many to list) can usually be calibrated, but often require a professional to perform the work.  Please call us at 800-390-0004 if you require assistance.