Hydrometer Calibration

[Andrew_Murphy]

I have a deep six hydrometer and I have not calibrated it yet. My question is can I calibrate it with regular table salt and water?

[Squawkbert]

If you have some highly pure RO/DI water, salt, a good graduated cylinder and an accurate balance, you can check your hydrometer.

Pure RO/DO should read 0.997-0.998g/cc at 20-25°C

If you dissolve a known mass of salt into a known volume of water, you can calculate your specific gravity (SG) by summing the mass of the water & salt and dividing by the total volume. Check this calculated value against your hydrometer's reading.

[sploke]

Why wouldn't pure distilled water read 1.000?

[Squawkbert]

It would, but only at 4°C. At room temperature, it should be 0.997-0.998.

[sploke]

Aren't most hydrometers calibrated for room temp? I know my brewing hydrometers are calibrated for about 65 degrees F. They're the glass floating type.

[mrtuskfish]

I have a deep six hydrometer and I have not calibrated it yet. My question is can I calibrate it with regular table salt and water?
Find someone who has a good refractometer (a GOOD lfs should) and compare your readings.

[mrtuskfish]

I have a deep six hydrometer and I have not calibrated it yet. My question is can I calibrate it with regular table salt and water?
Find someone who has a good refractometer (a GOOD lfs should) and compare your readings. (On a deep six, shouldn't most tap water register exactly 1.0?)