how to use a hydrometer for newbies

[sour_grapes]

They measure ABV directly. Not SG.

WADR, I do not believe that this is correct. If you follow the link you included, it indicates that those hydrometers are for "determining proof of ethyl alcohol spirits." The definition of ethyl alcohol spirit is a mixture of pure water and pure ethanol.

The link you provide indicates that the hydrometers are calibrated under the specifications of Circular 555 National Bureau of Standards for Testing of Hydrometers, which may be found here: https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular555.pdf

In that document, we read

3.1. Alcoholometers
Alcoholometers may be graduated to indicate the percentage of ethyl alcohol, either by weight or by volume, in mixtures of ethyl alcohol and water, or they may be graduated to indicate percentages of “proof spirit” as defined by the Bureau Internal Revenue, United States Treasury Department.[1]

[1]“Proof spirit” is that alcoholic liquor that contains one-half of its volume
of pure ethyl alcohol of a specific gravity of 0.7939 at 60° F, referred to water
at 60° F as unity. “Gauging Manual,” p. 7. 1938, U. S. Treasury Dept.,
Bureau of Internal Revenue. (The percentage of proof spirit is in every case
twice the percentage of ethyl alcohol by volume at 60°F.)

Put simply, these are hydrometers. They measure specific gravity of solutiuons. They are carefully constructed to be precise and accurate. They do not directly measure alcohol content of liquids. There is no physical mechanisim for a floating glass tube to directly measure alcohol in a solution.

 

[balatonwine]

WADR, I do not believe that this is correct.

I was referring to the units on the hydrometer. Not what physical properties were actually causing that measurement. And so I was indicating one needed really no "translation" from SG.

Hydrometers also come in other units of measure for the convenience of the reading being made. Such as Balling, Brix, Plato, Oechse, etc. Despite really all measuring pretty much the same thing. My hydrometer actually use the Klosterneuburger Zuckergrade which you probably never heard of.

I also stated that these were indeed designed for spirits, but could be used for wine "within tolerance**" for home wine makers (i.e. they will not be as exact .. but will give a very good ABV estimate without having to go to a lab).

Hope this helps.

** From: TTBGov - Wine Labeling: Alcohol Content

Alcohol content may be stated as a specific percentage with a tolerance of:

• Plus or minus 1 percentage point for wines containing over 14% alcohol by volume;

Example: A wine is labeled with the alcohol content statement “18% ALC. BY VOL.” Provided the actual alcohol content does not exceed 19% or fall below 17%, the label alcohol content statement “18% ALC. BY VOL.” is permissible.

• Plus or minus 1.5 percentage points for wines containing 14% or less alcohol by volume;

Example: A wine is labeled with the alcohol content statement “12% ALC. BY VOL.” Provided the actual alcohol content does not exceed 13.5% or fall below 10.5%, the label alcohol content statement “12% ALC. BY VOL.” is permissible.

 

[FlowerLabny]

Thank you...this tutorial helped out a lot.

 

[Jonboy6692.ja]

ok i want to start a thread on how to use and under stand a hydrometer.
as a relitive newbie, i look at the problem with a different perspective than the more experienced, when i got my first hydrometer, i didn't know crap about it
so i read the directions, and tutoriels, some were good and some were confusing

so this will be a work in process, and i welcome ANY constructive critisim to improve the topic.
View attachment 3211
this is a start, looking at the sg scale. i plan to do another pic relating the other scales as i have time
View attachment 3233
update

jim

A hydrometer should show your potential alcohol content. I adjust sugar to equal about 12.5 % alcohol.

 

[Shanghai Wine Maker]

All, as someone who is scientifically and mathematically minded I have found the whole hydrometer business incredibly confusing - how can one measurement tell me both sugar and alcohol content and why should SG from before fermentation tell me anything about how much alcohol I have now? Just mindlessly looking up numbers in charts doesn't do it for me.

At this point I think I understand it. I would like to confirm.

1. Before you start fermentation you have no alcohol in the juice. Therefore, when you measure SG you can determine the amount of sugar in the juice.
   1. Presumably other solids and dissolved substances that effect SG are negligible
   2. But I'm trying an apple wine, and my mashed apples started as mush, not liquid. Measuring SG with a hydrometer was impossible.
2. As sugar turns into alcohol the SG changes because SG from 1% sugar in liquid is different from SG from the alcohol that the 1% alchohol converts to.
   1. Therefore, we can caclulate alcohol content based on current SG and original sugar content (ie. SG)
      1. Assumes that other substances in the juice that affect SG are either unchanged or negligible.

Do I understand this correctly?

 

[Shanghai Wine Maker]

BTW, I bought this device - 淘宝网 - 淘！我喜欢 (watch the video, ignore the Chinese) which is supposed to measure alcohol content. Cost including shipping just USD 2.00 so why not try it?'

Based on the video, you drop some wine in the cup at the top, wait for it to flow out the hole at the bottom, then turn it upside down. You can then read the alcohol percentage from the final line that the wine goes up to.

Does anyone know:

1. What is it? Obviously not a hydrometer.
2. Does it work?
3. Is it measuring SG, viscosity, or something else?
4. Will it also measure sugar content before fermentation if I work out conversion scale?

 

[barryjo]

All, as someone who is scientifically and mathematically minded I have found the whole hydrometer business incredibly confusing - how can one measurement tell me both sugar and alcohol content and why should SG from before fermentation tell me anything about how much alcohol I have now? Just mindlessly looking up numbers in charts doesn't do it for me.

At this point I think I understand it. I would like to confirm.

1. Before you start fermentation you have no alcohol in the juice. Therefore, when you measure SG you can determine the amount of sugar in the juice.
   1. Presumably other solids and dissolved substances that effect SG are negligible
   2. But I'm trying an apple wine, and my mashed apples started as mush, not liquid. Measuring SG with a hydrometer was impossible.
2. As sugar turns into alcohol the SG changes because SG from 1% sugar in liquid is different from SG from the alcohol that the 1% alchohol converts to.
   1. Therefore, we can caclulate alcohol content based on current SG and original sugar content (ie. SG)
      1. Assumes that other substances in the juice that affect SG are either unchanged or negligible.

Do I understand this correctly?

One small item. If a substance is dissolved in liquid, it will affact SG. For example, sugar, salt, any number of chemicals. I guess technically, if a substance can settle out, it is not dissolved. As for alcohol calculation, Subtracting final gravity from starting gravity times 131.5 will equal alcohol by volume (ABV). Much less expensive than an ebulliometer.

 

[Jonboy6692.ja]

All, as someone who is scientifically and mathematically minded I have found the whole hydrometer business incredibly confusing - how can one measurement tell me both sugar and alcohol content and why should SG from before fermentation tell me anything about how much alcohol I have now? Just mindlessly looking up numbers in charts doesn't do it for me.

At this point I think I understand it. I would like to confirm.

1. Before you start fermentation you have no alcohol in the juice. Therefore, when you measure SG you can determine the amount of sugar in the juice.
   1. Presumably other solids and dissolved substances that effect SG are negligible
   2. But I'm trying an apple wine, and my mashed apples started as mush, not liquid. Measuring SG with a hydrometer was impossible.
2. As sugar turns into alcohol the SG changes because SG from 1% sugar in liquid is different from SG from the alcohol that the 1% alchohol converts to.
   1. Therefore, we can caclulate alcohol content based on current SG and original sugar content (ie. SG)
      1. Assumes that other substances in the juice that affect SG are either unchanged or negligible.

Do I understand this correctly?

The SG reading is potential
alcohol. What might be expected if all the sugar ferments to dryness.

 

[winemaker81]

how can one measurement tell me both sugar and alcohol content and why should SG from before fermentation tell me anything about how much alcohol I have now?

One measurement doesn't -- it's several measurements combined with an understanding of the changes in SG as yeast eats sugar and pees alcohol.

Regarding wine, the other constituents are considered negligible.

The amount of alcohol produced is not a linear curve -- there's actually several equations that approximate the amount of alcohol, and which equation to use depends on the actual amount of alcohol. Yes, the actual result determines which equation to use. The change in SG during fermentation is not a simple curve -- it's affected by the loss of sugar (heavier than water) and production of alcohol (lighter than water).

I suggest you simply accept that it works and don't overthink it.

The object in your second post is a vinometer. They are commonly regarded as junk and AFAIK, it doesn't really work. If you put anything with sugar in it, you'll gum it up and throw it out.

 

[barryjo]

BTW, I bought this device - 淘宝网 - 淘！我喜欢 (watch the video, ignore the Chinese) which is supposed to measure alcohol content. Cost including shipping just USD 2.00 so why not try it?'

Based on the video, you drop some wine in the cup at the top, wait for it to flow out the hole at the bottom, then turn it upside down. You can then read the alcohol percentage from the final line that the wine goes up to.

Does anyone know:

1. What is it? Obviously not a hydrometer.
2. Does it work?
3. Is it measuring SG, viscosity, or something else?
4. Will it also measure sugar content before fermentation if I work out conversion scale?

View attachment 89713

IIRC, this devise is useful only for white wines.

 

[Jonboy6692.ja]

One small item. If a substance is dissolved in liquid, it will affact SG. For example, sugar, salt, any number of chemicals. I guess technically, if a substance can settle out, it is not dissolved. As for alcohol calculation, Subtracting final gravity from starting gravity times 131.5 will equal alcohol by volume (ABV). Much less expensive than

One small item. If a substance is dissolved in liquid, it will affact SG. For example, sugar, salt, any number of chemicals. I guess technically, if a substance can settle out, it is not dissolved. As for alcohol calculation, Subtracting final gravity from starting gravity times 131.5 will equal alcohol by volume (ABV). Much less expensive than an ebulliometer.

Shoot for about 12 1/2 % alcohol for the average wine, sit back and relax then.

 

[Shanghai Wine Maker]

One small item. If a substance is dissolved in liquid, it will affact SG. For example, sugar, salt, any number of chemicals. I guess technically, if a substance can settle out, it is not dissolved. As for alcohol calculation, Subtracting final gravity from starting gravity times 131.5 will equal alcohol by volume (ABV). Much less expensive than an ebulliometer.

Right. But question is where this 131.5 number comes from.

It is because the sugar converts into alcohol and that changes SG from the original. Assumption is that all change in SG is due to sugar converting to alcohol.

I actually wonder how likely that is - all the lees that settle out should also make a difference, right?

BTW, why do we measure SG instead of density?

 

[winemaker81]

BTW, why do we measure SG instead of density?

SG is density, well at least the ratio against a known substance, water. Plus the tool used to measure is easy to use and cheap to manufacture. It does the job sufficiently.

The tool measures initial sugar content, works to let the winemaker how far along fermentation is, and when fermentation is done.