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THE HYDROMETER & ITS USES
Your hydrometer has been specifically designed for the amateur wine
and beer maker. It covers a relatively broad range, and therefore,
eliminates the need for several instruments of narrower ranges to
get the job done. A hydrometer is an instrument for measuring the
density of a liquid in relation to water. Water is given the arbitrary
figure of 1.000, and other liquids are compared to this figure. The
result is said to be their Specific Gravity (S.G. for short). As you
add sugar, malt extract, honey, or other soluble solids, the numbers
after the decimal point will increase. As the beverage ferments, the
sugars are converted into carbon dioxide and alcohol (lighter than
water), the numbers will decrease.
DETERMINING ALCOHOL CONTENT
Hydrometers have many uses, but the most common use by wine, beer,
and mead makers is determining the alcohol content of a homemade beverage.
This is quite simple, actually. 1) First, you must take a reading
prior to fermentation. It is impossible to accurately determine the
alcohol content of a fermented beverage without this initial reading.
Your hydrometer should have a scale called the "Potential Alcohol"
scale. This scale measures the amount of alcohol that will be potentially
produced if fermented to dryness (S.G. 1.000 or less). The easiest
way to take a reading is to sanitize a wine thief or "gravy baster",
then remove a sample of the "must" or "wort" and place this in the
test stand (this can even be the plastic tube the hydrometer comes
packed in). Fill the stand about 3/4 full, then carefully place the
hydrometer in it. Give the hydrometer a gentle spin with your thumb
and middle finger. This should remove any air bubbles that might otherwise
cling to the sides of the instrument. When the hydrometer has settled,
take the S.G. (and/or potential alcohol) reading with your eye at
the surface level of the liquid. Read the scale inside the instrument
at the level where the liquid contacts the glass. 2) After the fermentation
is completed, take another reading. Subtract the potential alcohol
reading at this point from the potential alcohol reading prior to
the fermentation. The difference between the two numbers is the alcohol
content that you have actually produced. For example: if the initial
reading is 13% and the final reading is 1%, then the actual alcohol
content is 12% (or 13% - 1% = 12%). Please note that if your beverage
ferments completely dry (S.G. of 1.000 or less), then the alcohol
content is the same as your original potential alcohol reading (in
the above example: 13% - 0% = 13%). The reason that the final gravity
might end up lower than water is that you are producing alcohol, which
is noticeably lighter (less dense) than water. All dry wines and meads
will finish at gravities lower than 1.000 (e.g. .995). Almost all
beers and sweeter wines & meads will finish higher than 1.000.
USES FOR WINEMAKERS
The hydrometer can be used to determine the natural sugar content
of the "must." In most instances additional sugar should be added
to this "must" to assure that the alcohol content of the finished
wine is sufficient for the wine to keep. Alcohol is a preservative,
and you should insure that your wine have alcohol content of at least
9 - 10%. Lower strength wines will be susceptible to spoilage. By
determining the natural sugar content you can then adjust the sugar
content to the desired S.G. reading. In many cases a S.G. of 1.090
is desired to begin the "must," as this give a potential alcohol by
volume of 12%.
PROCEDURE FOR WINEMAKERS
1. After sanitizing a wine thief or gravy baster, remove a sample
of the "must" and place it in the test stand. Take a reading, then
refer to the accompanying hydrometer chart. This will indicate the
natural sugar content in the"must."
2. To determine how much additional sugar is necessary to bring the
"must" to the desired S.G. (let's say 1.090), use the attached chart.
For example: If the initial gravity reading is 1.040, then each gallon
of juice contains the equivalent of 1 lb. 1 oz. of natural sugar content.
If you consult the chart, at the desired level of 1.090 (12% alcohol),
the sugar content should be 2 lbs. 6 oz. Now do the arithmetic:
(desired O.G.) - 1.090, there is: 2 lbs. 6 oz. sugar
per gallon
(initial O.G.) - 1.040, there is: -1
lb. 1 oz. sugar per gallon
difference (sugar to be added): 1 lb. 5 oz. sugar per
gallon
By subtracting the two sugar contents, you determine how much additional
sugar should be added per gallon. It is not necessary (but still not
a bad idea), to dissolve the sugar in some boiling water before mixing
into the "must."
3. Note that as a general rule of thumb, 1 lb. of sugar dissolved
in 5 gallons of "must" will raise the potential alcohol content by
approximately 1%. Therefore, if you check the gravity of the must
and it reads a potential of 9%, and you wish to produce 12%, simply
add 3 lbs. sugar. Note, this is for 5-gallon recipes.
HYDROMETER CHART S.G. Potential; Amount of Alcohol % Sugar in by Volume the Gallon lb. oz. 1.010 0.9 --2 1.015 1.6 --4 1.020 2.3 --7 1.025 3.0 --9 1.030 3.7 -12 1.035 4.4 -15 1.040 5.1 1 -1 1.045 5.8 1 -3 1.050 6.5 1 -5 1.055 7.2 1 -7 1.060 7.8 1 -9 1.065 8.6 1 -11 1.070 9.2 1 -13 1.075 9.9 1 -15 1.080 10.6 2 -1 1.085 11.3 2 -4 1.090 12.0 2 -6 1.095 12.7 2 -8 1.100 13.4 2 -10 1.105 14.1 2 -12 1.100 14.9 2 -14 1.115 15.6 3 -0 1.120 16.3 3 -2 1.125 17.0 3 -4 1.130 17.7 3 -6 1.135 18.4 3 -8 |
PROCEDURE FOR BEER BREWERS
1. After sanitizing a wine thief or gravy baster, remove a sample
of the "wort" and place it in the test stand. Take a reading, and
record this information. This will give you a guidepost by which to
compare any subsequent readings.
2. If you are fermenting beer using the two-stage method, you will
want to take a second reading after the initial fermentation has slowed
down and you are ready to rack the beer into the secondary. If all
is going according to plan, this reading should be 1/3 of the original
gravity (O.G.) or less (e.g. O.G. - 1.048, racking gravity 1.016 or
less). If the gravity is noticeably higher than 1/3 the O.G. then
you have a "stuck" fermentation. Call us for suggestions as to how
to remedy the situation.
3. At bottling time, check the S.G. again. As a rule this reading
should be 1/4 to 1/5 of the original gravity or less. Most recipes
will give a target final gravity. If your final gravity is more than
.003 to .004 above this target, you may have a problem. Again, call
or e-mail us for suggestions.
TEMPERATURE CORRECTION
Please note that most hydrometers are calibrated at 60°F and sample
temperatures higher or lower than this will need to corrected. Consult
the accompanying correction chart to determine the amount of the adjustment.
For example: if your sample reads 1.045, but it is at 84°F, then you
need to add .003 for an adjusted reading of 1.048.
| TEMPERATURE CORRECTION CHART Temperature of sample (°F) Reading Correction 50° -.0005 60° .000 70° +.001 77° +.002 84° +.003 95° +.005 105° +.007 |
