I can't believe I never thought of this before

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KayaBrew

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I know how to calibrate my thermometers-place into an ice water slurry hit the "Calibrate" button on my digital, manually turn the dial to 32F on my analog.

That was the setup, here's the rub:

How do you "calibrate" a hydrometer? You place it into 60F distilled water. If it reads 1.000, you're good. If it's off, then what? You've got a bum hydrometer. You can't actually "calibrate" it now, can you?:ban:
 
You note how much its off. Every time you take a reading, add or subtract that much.

Yeah, that's the only answer I came up with. I guess my point was that you can't really calibrate it or "zero it". It doesn't matter in my case anyway, because my old hydro works fine, and I just picked up a new "precision" hydro that reads from 1.000 to 1.080. It should make my SG readings a little more accurate.
 
I got one of the unbreakable hydrometers (plastic) comes with a weight you add to the bottom to measure higher gravity (markings on one side) so it is really accurate. It was a little heavy when I got it so I kept clipping off plastic until it read 1.000 in distilled water. (It has a place at the top marked with lines to do specifically this)

If your glass hydrometer is a little light you could put dabs of epoxy on it until it is calibrated.
 
Marking an offset is one method of calibration. It's the only method available if the instrument cannot be adjusted.
 
I've calibrated my standard LHBS glass hydrometer by carefully tapping the appropriate end against a countertop thus moving the paper insert. Don't blame me if you break yours though!
 
I don't see a reason to calibrate it. Your readings are for taking the FG-OG right?

So if your starting gravity will be off, the final gravity is off the same amount. The subtracted number is the same.

1.10-1.00=.10 as 1.35-1.25=.10

Still the same number. Calibrating Temp may be off too. As ice can be diffrent temps, especially in a slurry. Ever check the temp of an Ice slush when you put salt in it? Much colder.
 
you can calibrate it in beer programs so it automatically gives you the correct reading with out the extra math. this only works if you use certain beer software.
 
Calibrating Temp may be off too. As ice can be diffrent temps, especially in a slurry. Ever check the temp of an Ice slush when you put salt in it? Much colder.

Ice and water slurry will ALWAYS be 32*. If you add salt, you no longer have an ice and water slurry. We're not making ice cream here, leave the salt out of it.
 
I believe 'How It's Made' covered the calibration procedure. They filed off some of the lead weight until it measured correctly. Adding more wouldn't be too difficult. This is assuming you have an exposed, lead base.
 
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