There are many factors that affect the calibration of glass thermometers. First of all, the quality and characteristics of the thermometer itself will affect the calibration results. Examples include the glass material of the thermometer, the uniformity of the scale, and the performance of the temperature sensing element.

Secondly, environmental factors such as temperature, humidity and air pressure have a significant impact on the calibration process. Excessively high or low temperatures may cause thermometer readings to deviate, and humidity and air pressure can also affect the measurement accuracy of thermometers.

In addition, the accuracy and stability of the calibration equipment can also affect the calibration results. Highly accurate calibration equipment can provide more accurate temperature measurements, while poor stability of the equipment can lead to calibration errors.

The operator's operating methods and skills can also have an impact on calibration. Examples include the way thermometers are placed, how they are read, and the steps taken during the calibration process.

Understanding these influencing factors will help to take appropriate measures during the calibration process to improve the accuracy and reliability of the calibration.