How can you calibrate an outdoor liquid thermometer correctly?

I have this outdoor liquid thermometer & I decided to calibrate it by putting it into ice water, the alcohol went down and it was a little off zero degrees Celsius, so I marked on the glass tube where the alcohol stopped, then I lined the mark up with zero on the thermometer's scale.

But for some strange reason, the thermometer never reads the correct temperature, it's usually a couple of degrees above the accurate temperate (as I have a calibrated digital thermometer)

Isn't ice water supposed to be zero degrees Celsius (or 32F?)

Update:

It always seems like when you buy a liquid thermometer, it NEVER reads zero or 32F when you test it with ice water, the alcohol usually stops either above it, or below... so why do they apparently make them this way?

4 Answers

Relevance
  • 9 months ago

    You only get 0 degrees if you use a stirred ice bath and distilled water. Try it again.

  • 9 months ago

    Calibrating at 0 C doesn't mean it's calibrated for 20 C. And cheap thermometers are always going to be off. Ask a doctor how much a good alcohol thermometer costs.

  • 9 months ago

    you have a "calibrated digital thermometer", use that to calibrate the other one. 

  • 9 months ago

    Fill a large glass with ice and then fill it with cold tap water. Stir the ice water and let it sit for 3 minutes. Place your thermometer in the ice water, making sure to stick the probe at least 2 inches into the mixture, but not to touch the sides or the bottom of the glass. Stir the ice water with the probe to even out the temperature of the water and prevent the probe from resting against an ice cube. Wait at least 30 seconds for the thermometer to read the temperature. The temperature on your thermometer should read 32°F or 0°C.

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