Hydrometer Calibration without Distilled Water

[FatDragon]

It's not that distilled water is impossible to get here in China, but I don't know of any places locally that sell it, and I'm hoping to check the calibration on my hydrometer before my next brew. Is there some other way to do it, or do I have to do something tremendously silly and order a single bottle of distilled water online to calibrate my hydrometer(s, the second is a local Chinese hydrometer of dubious accuracy, not just calibration).

I was trying to think of other things that might have consistent density, but I'm coming up with a blank - things like milk and juice and even (call me crazy) vinegar, soy sauce, and cooking oils would vary from jug to jug and especially across different providers, and sodas would be right out between carbonation and slightly less-sweet recipes here in China. Tap and (non-distilled) bottled water are also unknown quantities. As for liquors, I'm not certain they would be 100% consistent across bottles, and I'm not really sure if I would want to pour an 8 oz hydrometer sample of Bombay Sapphire or Jameson (or one of my single malts) back in the bottle, and I'm certain I wouldn't want to drink it all off.

Finally, if I calibrate and find distilled water (or whatever adjunct I use) is off, will that offset be consistent across the whole range, or do I need to do further experimentation by checking multiple known gravities (achieved by adding carefully-calculated amounts of corn sugar to the sample)?

 

[invivoSaccharomyces]

It is more important to calibrate using the water you use for brewing. If you calibrate to distilled water, you will have to compensate for the dissolved salts in your brewing water anyway.

 

[FatDragon]

It is more important to calibrate using the water you use for brewing. If you calibrate to distilled water, you will have to compensate for the dissolved salts in your brewing water anyway.

Water chemistry and salt additions are at least a few batches down the road for me, but point taken. I'll test against the bottled water I'm brewing with, then.

What about the question of consistency? If my bottled water comes in at, say, 0.996, and I get an OG of 1.046 at the same temperature, does that mean my OG is 1.050, or will the offset value vary as the gravity changes?

 

[AlCophile]

Fat:
You oughta be able to get a small amt. of DW easily. Can you get a clean container to condense some steam? You need only enough to float the h'meter, not cause a flash-flood. Just shoot some steam from a teapot(you DO have tea in China?) thru a tube into a cool container. Just be sure to heat the condensate enough to drive out dissolved air, and oilas! Hell, rain water should be close. You're making beer, not sterile saline.

 

[Hex23]

Using tap water is not likely to cause your calibration to be off by that much. Using distilled water is ideal, but I'd bet that a vast majority of tap water is less than 1.001. Edit or +/- 0.001 anyway

 

[Hex23]

What about the question of consistency? If my bottled water comes in at, say, 0.996, and I get an OG of 1.046 at the same temperature, does that mean my OG is 1.050, or will the offset value vary as the gravity changes?

Your question made me remember this conversation: https://www.homebrewtalk.com/f128/measuring-p-p-g-233412/index2.html#post2760024 ...

Based on this the answer is generally yes, you'll be off by 4 points across the scale: To paraphrase the above link, any non-linearity in the hydrometer is minimal across the scale and the most common source of inaccurate calibration is the paper not being positioned correctly.

Myself and others have experienced strange results with very high temperatures. Apparently temperature correction only goes so far, so try to keep the measurement temps close to the calibration temp of the hydrometer.

 

[FatDragon]

Using tap water is not likely to cause your calibration to be off by that much. Using distilled water is ideal, but I'd bet that a vast majority of tap water is less than 1.001. Edit or +/- 0.001 anyway

I dunno - China's tap water is a major "boil before drinking" offender. There's no telling what's in the water here, but it's not good. The uncertainty about the water is most of the reason I use bottled water instead of tap water for brewing; although anything harmful will die in the boil, that doesn't mean it's not loaded with all kinds of minerals and chemicals that could make my beer taste bad.

The bottled water could have the same issues with minerals and chemicals, but at least it tastes good coming out of the bottle. Boiled Wuhan water still tastes horrible, even if it won't kill you.

 

[IvanTheTerribrew]

That sucks about your water, glad you're using bottled water. That would worry me too. And while I don't have good input for your problem I will say, the answer given about "if it's off by X, it's always off by X" is actually an answer I've been looking for myself. With distilled water my hydro was at like 1.003. And that was at about 63* F. Now I'll try it with the water I brew with and know that that will be my offset. Thanks!