When calibrating glass thermometers, the following precautions should be taken to ensure the accuracy of calibration results:

1. Choose the Appropriate Calibration Method
   Select a suitable calibration method based on the thermometer's usage range and accuracy requirements. For example, the ice point and boiling point methods are suitable for calibrating 0°C and 100°C points, while the comparison method is suitable for multi-point calibration.

2. Control Environmental Conditions
   Avoid temperature fluctuations, air currents, and direct sunlight during calibration, as these factors may affect the results.

3. Handle the Thermometer Correctly
   Avoid touching the thermometer's bulb directly during calibration to prevent affecting the reading. Ensure the thermometer is inserted vertically into the calibration medium to avoid tilting.

4. Record Calibration Data
   After each calibration, record the date, method, environmental conditions, reference thermometer readings, and error values of the thermometer being calibrated for subsequent analysis and tracking.

Common Issues:

• Unstable Thermometer Readings: This may be due to environmental temperature fluctuations or uneven liquid inside the thermometer. It is recommended to recalibrate in a stable environment.

• Damaged Thermometer: If the thermometer has cracks or a broken liquid column, stop using it immediately and replace it with a new one.

• Inconsistent Calibration Results: This may be due to improper calibration methods or inaccurate reference thermometers. It is recommended to recheck the calibration process and equipment.