4 Ways to Fix a Mercury Thermometer

Table of contents:

4 Ways to Fix a Mercury Thermometer
4 Ways to Fix a Mercury Thermometer

If the column of mercury (or other indicator fluid) in a thermometer separates, the void will result in an incorrect temperature measurement. Here are some ways to remove this empty space in the column. Read all the steps before trying to do something.


Repair Mercury Thermometer Step 1

Step 1. Inspect the thermometers for damage

Do not use it anymore if it is cracked or otherwise damaged. In this case, it has reached the end of its useful life and needs to be disposed of properly (see the warnings section below).

Repair Mercury Thermometer Step 2

Step 2. Write down the indicated temperature

Repair Mercury Thermometer Step 3

Step 3. Choose a method to repair the separated mercury

Method 1 of 4: Cooling

This is the simplest method to fix the thermometer. However, note that it can have mixed results.

Repair Mercury Thermometer Step 4

Step 1. Place the thermometer in the refrigerator or ideally the freezer

If it cools down enough, it should simply send the mercury (or other indicator fluid) into the bulb. See the next steps if you don't have a refrigerator or freezer available or if it doesn't work.

Method 2 of 4: Heating

This method may require several attempts.

Repair Mercury Thermometer Step 5

Step 1. Place the thermometer in the sink

Repair Mercury Thermometer Step 6

Step 2. Gradually heat the bulb with a hair dryer in warm

The mercury will rise to the top of the thermometer and unite again.

Repair Mercury Thermometer Step 7

Step 3. Allow the thermometer to gradually come to room temperature

Repair Mercury Thermometer Step 8

Step 4. If you need to make several attempts, warm up and cool down gradually

Do not overheat as the thermometer may explode.

Method 3 of 4: Agitation

This method is quite reliable as it has been used extensively in hospitals, etc. before electronic thermometers and disposable temperature strips became commonplace. There is, however, a risk of losing control of the thermometer while shaking, resulting in breakage and spread of mercury.

Repair Mercury Thermometer Step 9

Step 1. Firmly hold the thermometer near the top so that the bulb containing the mercury (or other indicator fluid) is facing downwards

Repair Mercury Thermometer Step 10

Step 2. Quickly move the thermometer downwards and abruptly change direction (and flex the wrist upwards)

Bring the thermometer to its lowest point several times.

Repair Mercury Thermometer Step 11

Step 3. Check the indicated temperature again

If the temperature is lower than noted above, continue shaking down. This may take several repetitions until the empty space in the column disappears.

Method 4 of 4: Dropping

This method appears to have the best results, but there is a risk of breaking the thermometer if dropped on a very hard surface or from a very great height.

Repair Mercury Thermometer Step 12

Step 1. Hold the thermometer vertically – bulb down

Repair Mercury Thermometer Step 13

Step 2. Drop the thermometer on the bed, pillow or even towel folded so that it is 8 (or more) times its original thickness

No more than 30 to 60 cm d and drop is recommended.


  • Store thermometers horizontally or upside down. Never store them with the bulb up.
  • Don't forget to wash your hands.


  • Consider discontinuing the use of mercury-containing thermometers if they are to be used in the kitchen or as a clinical thermometer. As mercury is highly toxic, it is not good to use it in food or in the body. Newer electronic thermometers and those that use a mixture of alcohol and red dye are much easier to read and safer to use.
  • Do not simply throw away a device containing mercury. Mercury is a highly toxic heavy metal. In many places, inappropriate disposal of mercury is illegal. Contact your nearest city or pharmacy to learn how to dispose of thermometers and other devices containing mercury. Never mix objects containing mercury with normal household waste.

Popular by topic