The hydrometer is one of the most important instruments for home wine and beer making.
The hydrometer provides valuable information of the following things: – What the dissolved sugar content of the wine must / beer wort is before adding additional sugar. – How much sugar should be added to achieve a particular alcohol strength. – Helps ensure that too much sugar is not added. – How the fermentation is going. – When the wine or beer has been completely fermented. – Information for calculating the alcohol content of finished wine or beer. – How much sugar should be added for sweetening wine.
The floating hydrometer is used to measure specific gravity (SG) of liquids. In wine and beer this practically means the amount of dissolved sugar in the wine must or beer wort. The most commonly used hydrometer scale in home brewing is Oechsle (°Oe).
The starting point is the specific gravity of water (1000 g / liter at 20°C). This is marked on a scale differently, depending on the manufacturer. Either by reading 1.000 or 0. The scale usually ranges between 1.130 (130) and 0.985 (-15), of which the latter is 15 oechsle degrees below the specific gravity of water. Dissolved sugar, being heavier than water, raises the specific gravity.
Alcohol, being lighter than water, lowers it. 2,5 grams of sugar in 1 litre of water increases the specific gravity value by one degree oechsle (1°Oe = 2,5 g/l sugar).
One degree on the oechsle scale equals one gram of weight per litre. A liquid of 1.020 on the oechsle scale weighs 1020 grams per litre.
The hydrometer is used by letting it float freely in the liquid to be measured. Measuring is easiest in a transparent container high enough to float the hydrometer freely. A measuring cylinder, for instance.
The hydrometer must float freely and may not touch the sides of the cylinder. When the hydrometer settles in the liquid, a reading is taken at the surface level of the liquid on the scale.
The higher the reading, the more sugar there is in the liquid, and vice versa.
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Estimating the amount of sugar needed Example: We want to prepare 20 liters of wine with an alcohol content of 14% ABV (alcohol by volume). Our main ingredient in this wine would be 5 litres of concentrated berry juice. 17 grams of sugar per litre of water results in one percent of alcohol by volume. Thus, 20 litres of wine at 14% ABV would need 4760 grams of sugar. The formula is as follows: 20 (liters) x 17 (g sugar / liter) x 14 (alcohol%) = 4760 grams. Berry juice contains sugar of its own, as well as possible added sugar. But how much does it contain? We can calculate this by measuring the specific gravity of the juice. If the reading is, for instance, 1.060 (+60), then that means 150 grams of sugar per liter of juice (2,5 g/l x 60). And because the total volume of juice is 5 litres, there will be a total of 750 grams of sugar (5 litres x 150 grams = 750 g). When this amount is deducted from the total amount of sugar, the amount of additional sugar required is about 4 kg (4760 g – 750 g = 4010 g). With this total amount of sugar (if fully fermented) we will have a wine with an alcoholic content of about 14% ABV. Note! The original gravity (OG) of wine must should not exceed 1.120 (120) when pitching the yeast. This is to avoid overstressing the yeast. Therefore, strong wines are usually started with only 4 kg of sugar, with the remaining amount of sugar added after a few days, when the fermentation already is well underway. |
Calculating the alcoholic content of finished wine
How much sugar was there originally? And how much is there left? – When the amount of fermented sugar is known, we can calculate the alcoholic content.
Example: Our wine raw materials were estimated to contain about 750 grams of fermentable sugar, while another 4 kg was added to make a total of 4,75 kg of sugar. The amount of wine must (excluding the volume of solids) in our example was 20 liters.
Given these values, there was 237,5 grams of sugar per litre. The original gravity (OG) is thus about 1.095. The fermentation of our wine had for some reason stopped at a final gravity (FG) of 1.010 (+10). If the wine had fermented completely, the final gravity would have dropped by yet 15 degrees to 0.995 (-5). The difference between the desired final gravity and the actual final gravity is therefore 15, which is equivalent to approximately 37,5 g per liter of unfermented sugar. The fermented amount of sugar is therefore 200 g per liter of wine (237,5 g – 37,5 g = 200 g). Since every 17 grams of sugar per litre results in 1% ABV, our wine would contain about 11,75% ABV (200 : 17 = 11,75). The other way around:
Approximately every 7,5°Oe decrease on the specific gravity scale during fermentation increases the alcohol content by 1% ABV.
When the original gravity (OG) and the final gravity (FG) are known, the difference between these two values can be converted into alcohol content by simply dividing it by 7,5. If the difference in our wine is for example 85 (1.095 – 1.010), then the alcohol content of our wine is 11,3% ABV (85 : 7,5 = 11,3). Please note that these two calculation methods result in slightly different values (11,75% vs. 11,3%). In home making, we rarely get 100% accurate results by calculating with these rounded numbers, but the results we get are still usually close enough..
Contents
How to Use a Specific Gravity Hydrometer
How to use a specific gravity hydrometer is easy if you follow along. This hydrometer measures the specific gravity (SG) and potential alcohol (PA).
The specific gravity hydrometer also called the triple scale distilling hydrometer provides 3 choices of readings in one hydrometer. The reading we focus on when we use this hydrometer is the Specific Gravity (SG).
Watch the Hydrometer Video Tutorial
The 3 Scales on the Gravity Specific Hydrometer
- Specific Gravity: (0.99-1.16)
- Potential Alcohol: (0%-20%)
- Brix/Balling: (0-35)
Each reading is different depending on what of spirits you are making. Refer to the instructions that came with the hydrometer you purchased.
What Does a Specific Gravity Hydrometer Measure?
A specific gravity hydrometer measures the sugar content of the wash and the mash to determine the potential alcohol (PA). Many distillers will also call the specific gravity a “brewing hydrometer”. Yes, it can be very confusing for all the “names and labels”.
Today, we will only be discussing and demonstrating the specific gravity hydrometer and how to use it.
When to Take a Specific Gravity Reading?
The specific gravity hydrometer is used 2 or more times during the moonshining process. The first reading is before adding or pitching the yeast. The second reading is when the fermentation has stopped in the mash, wort, or wort. Grab your Batch Record Labels!
How to Take a Specific Gravity Hydrometer Reading
Taking a reading with a specific gravity hydrometer is easy. Make sure you have enough liquid in the test jar at least up to the top reading on the jar. If you purchased the hydrometer kit, a 250 ml test jar will be included.
The specific gravity hydrometer kit with the glass test cylinder is highly recommended over the test kit with the plastic cylinder for many reasons. The glass cylinder is easier to sanitize and keep clean and the plastic cylinder which is much harder to clean and see-through.
Hydrometer Wisdom: Monitoring Fermentation
As with all matters of life, there are two ways of monitoring the fermentation of your mash: the easy way and the complicated way.
If you’re a K.I.S.S. fan – not the band, but the „Keep It Simple, Stupid” philosophy – you’ll prepare the mash and just let it be. A day or two after adding the yeast, you’ll see the airlock bubble – and know the stuff’s doing its fermenting business.
After 14 days, it should be about done. If it still bubbles, let it sit for another few days, or until you see no bubbling for at least a minute or two. Once there is no activity in the airlock, your mash is ready to run.
This is a non-scientific method but pretty reliable in judging when fermentation is completed.
The scientific method isn’t actually that complicated either, and it will let you know that the mash has completely finished fermentation and determine its potential alcohol. What you’ll need is a beer or wine hydrometer.
The hydrometer indicates the density, or specific gravity – SG – of a liquid, compared to water. As alcohol is thinner than water, the higher the alcohol content, the deeper the float sinks. Pure water has a specific gravity of 1.000 on the hydrometer scale.
Temperature is a key factor when measuring the specific gravity of a liquid – the hydrometer should indicate the temperature it’s calibrated to, and also include an adjustment table. A standard measuring temperature is 20°C or 70 °F.
Original Gravity – OG
Measure the gravity of your mash before fermentation – and before adding the yeast. The reading will be higher than 1.000, because of the sugars present in the mash. During fermentation, these sugars will be consumed by yeast causing the density and therefore specific gravity to lower. The number will be the lowest at the end of fermentation.
Fill your hydrometer tube about 2/3 of an inch from the top with the wash/mash you wish to test. Insert the hydrometer slowly not allowing it to drop. Give the hydrometer a light spin, to remove the air bubbles that may have formed.
Read where the surface of the liquid cuts the scale of the hydrometer.
You can also predict the potential alcohol of your mash from the original gravity.
Original Gravity – Potential Alcohol
- 062 → 7.875%
- 064 → 8.125%
- 066 → 8.375%
- 068 → 8.625
- 070 → 8.875%
- 072 → 9.125%
- 074 → 9.375%
- 076 → 9.75%
- 078 → 10%
- 080 → 10.25%
- 082 → 10.5%
- 084 → 10.75%
- 086 → 11%
- 088 → 11.25%
- 090 → 11.5%
- 092 → 11.75%
- 094 → 12.125%
- 096 → 12.375%
- 098 → 12.75%
- 100 → 13%
- 102 → 13.25%
- 104 → 13.5%
- 106 → 13.875%
- 108 → 14.125%
Final Gravity – FG
Measure the specific gravity of the mash after the airlock slows down and you’re not getting much activity. If the reading is at 1.000 or less, it is definitely done. If it’s 1.020 or higher, you may want to wait a day or two and then take another reading. Keep taking readings, if needed, until the gravity stops dropping – which means the fermentation is complete.
A good rule of thumb: if the gravity hasn’t changed over the course of three days, then the mash is done fermenting.
Final Gravity – Potential Alcohol
Using the chart above and some math, you can calculate the alcohol content of your mash after fermentation is complete.
ABV = (OG – FG) x 131
What Specific Gravity is in Wine Making! (Get The Research!)
If you’re an avid at-home-winemaker you must know by now that winemaking is way more than mixing grape juice, water, and some sugar, right? Right.
If you’re new to this world, expect to grab a calculator, learn a bit about chemistry and specifically called “specific gravity” respectively.
What is Specific Gravity in Winemaking? The specific gravity refers to the ratio of the density of a liquid to the density of water. It also indicates amounts of fermentable sugar or possible alcohol percentage in the must or wine. Water holds a specific gravity of 1.000. Wine, on the other hand, increases its gravity as you add sugar, for example, 1.015 in wine.
Overwhelmed? Let us break it down for you and teach you everything you need to know about Specific Gravity in winemaking.
Read Also: Is A Refractometer More Accurate Than A Hydrometer?
Why Measure Specific Gravity When Making Wine?
Winemaking is a great experience, especially if you’re just starting out. Don’t let math, chemistry and a little physics get in the way of a great winemaking process.
Because in all honesty, it might just take more than just combining a few ingredients if you want to nail your best recipe yet.
After the first fermentation in your wine has abated, which occurs at about seven days, it’s time you measure/check the specific gravity. This will help you figure out how the density of the must/wine compares to that of the water.
Fact: Grape juice is denser than water.
Let’s take a look at some numbers. Before the grape juice fermented, the specific gravity for it was over 1.0. Once the yeast started converting the sugar into carbon dioxide and alcohol during the fermentation process, the density of the wine starts to decrease.
For instance, a specific gravity measurement that is less than 0.990 indicates that the first fermentation has decreased enough to start racking.
The main concern? Leaving the wine in dead yeast for an excessive period of time. Then again, wine is oftentimes left sitting in decomposing yeast to convey a nutty flavor.
TIP: Unless you are an experienced winemaker and know exactly how much time is right, it’s best to play it safe and not leave the wine in dead yeast for too long.
How to Ferment for Higher Gravity
Want to ramp up the ABV (Alcohol By Volume) of your homebrew? Yeah. We know you do. The best way to increase the ABV is to add more fermentable sugar for your yeast to snack on. Unfortunately, dumping a few extra cups of sugar into your wort, and praying for success won't get you the beer you want. But there are steps you can take to ensure you will. Here's how.
High Gravity Yeast
This is the most important step. Think about the yeast you're going to use. Can it handle an increase in sugar? All beer yeasts are not created equal, and some strains simply don't have the manpower (read: cell-power) to produce any more alcohol.
What's more, even if the strain can produce a higher percentage, if the cell count is too low, it will become stressed. Stressed yeast produces off-flavors and other unpleasant characteristics. To avoid that outcome, you may need to make a yeast starter.
Increase ABV With Malt Extract
Here's what you need to know about changing the volume of malt extract in your brew. When it comes to increasing gravity one pound of dry malt extract will add approximately 1.008 specific gravity points per 5 gallons, and one pound of liquid malt extract will add approximately 1.007 specific gravity points per 5 gallons. When adding malt extract the following may occur:
- Increases the overall body of the beer
- Results in a higher finishing gravity
- Sweeter malt taste
- Potentially have a less perceived hop bitterness
- Can add a spicy flavor and aroma
- Could increase alcohol warmth
Adding Simple Sugars To Increase ABV
Simple sugars are another great option to boost ABV. One pound of sugar adds approximately 1.009 specific gravity points per 5 gallons. If you do add more of simple sugars (ie. corn sugar, table sugar, honey, Brewer's Crystals) the following may occur:
- Increased dryness
- The decreased overall body in the beer
- Increased perceived hop bitterness
- Too many simple sugars can result in poor fermentation
- Spicy flavor and aroma as well as increased alcohol warmth
Finding Balance With High ABV Beers
Increasing alcohol content will alter the intended flavor, aroma, and texture of the finished beer. Recipes are formulated to create a balance between the malt sweetness, hop bitterness, and other fermentation characteristics. Changing ABV messes with the original recipe's balance.
You'll need to experiment. That might mean upping the number of other ingredients (hops & additives) to maintain a balance of flavor and aroma, or it might mean something else entirely. Have fun experimenting!
For helpful tips on how to boost the ABV of your homebrew, watch the video below.
Read More About Fermentation:
- Fermentation – Learn about fermentation for beer.
- Cold Crashing – So what is brewing yeast anyway?
- Controlling Fermentation Temperature – Make sure your yeast is happy with the temperature.
- Stuck Fermentation – Helpful tips to get your fermentation rolling.
- Begin or continue your homebrew education with Northern Brewer University and our Homebrew Video Courses.
Trouble Shooting Spirits & Liqueurs
My wash failed to start fermenting?
The first thing to do is to check the wash with a hydrometer. It might well be the fermentation has finished. If your hydrometer reads correctly, the reason that bubbles might not be coming through the airlock is that your fermenter may not be sealing.
Remove the lid of the fermenter to check to see if there are any bubbles rising through the liquid or any froth on the surface or around the sides which would indicate the fermenter not sealing. Alternately, the temperature may be too low or high. Fermentation should start as low as 15°C.
If the wash is below this, add heat using a Heat Tray
, Immersion Heater
or Brew Belt
. If you added the yeast to the wash when it was too hot you may have killed the yeast. In this situation, you should not add more Turbo Yeast as this will result in too much nutrient.
Add a Wineworks Restart Yeast and add this to the wash when the temperature is 20°C. My wash started to ferment but stopped and my hydrometer reading is not down to, or bellow 990 SG?
It’s probable the temperature rose too high in the first 24 hours of fermentation. It’s important to note that yeast activity can raise the wash temperature by as much as 6°C in the first 24 hours of fermentation.
It’s essential to start the wash at around 20°C and not use any heat in the first 24 hours. If the wash overheats during this period the yeast may not have the energy to finish fermenting. If this has occurred, first stir the wash vigorously to stir the yeast back into circulation.
If the SG has not lowered within 24 hours then obtain a Wineworks Restart Wine Yeast. As there is alcohol present you should first start the yeast working in 200 ml of water. Once the yeast has dissolved, add a teaspoon of sugar. When this is fermenting, add 200 ml of wash.
When this is fermenting add half of this back to the stuck wash and top back up with more of the wash.
Continue this until the wash starts fermenting. Alternately, it may be because the wash has cooled down below 15°C. In this case, warm up the wash and stir vigorously to get the yeast back into circulation.
Once the wash is warm fermentation should continue normally. I have tried to get the wash going again but nothing seems to start it? Distill it anyway.
You will not get as much alcohol as you would from a normally fermented wash, but it will be fine.
Distillation – Airstill
I did not get as much alcohol as the instructions said I would?
Check that you have used the right quantity and type of sugar. The reason could be that your wash has not fermented fully.My alcohol is not as strong as the instructions said it would be?Check as above. If the alcohol is not in the wash then you can’t distill it.
Why is my distillate blue?
Ensure you have used Still Spirits Turbo System products (some brands produce a blue spirit due to an imbalance of nutrients). Use only one Turbo Yeast sachet per 25 Litre wash—if the fermentation sticks do not add another Turbo sachet as this will result in an imbalance of nutrients. Instead add an alcohol tollerant Restart Yeast
.
Specific Gravity, Brix, & Plato Conversion Calculators
We all have studied the process of alcoholic fermentation in our high school chemistry classes. Just to refresh your memory, fermentation is simply the conversion of sugars, be it glucose, sucrose, or fructose, into alcohol and carbon dioxide.
Simply put: no sugar = no alcohol.
The primary content of beer is its alcohol content, and there is so much that can change due to a minute change in its alcohol content. It’s what makes up a the taste of the drink or even its gravity, as we will take a look at below.
If you are a brewer, you need to look at establishing the alcohol contents of your brew. For it, there are a set of calculations that you need to do first. These calculations are an integral part of the beer brewing process and determine the decision and -process being done in the breweries.
What is Specific Gravity?
The specific gravity of any liquid is referred to its density when compared to water. Now, in the case of beer, various factors attributed to the thickness of a brew. Your beer has traces of sugar, starches, hops, malts, oil, and minerals.
Many brewers measure this specific gravity of the beer before beginning the fermentation process. They also do it after the culmination of the fermentation process. These brewers, then make use of this data and some calculating algorithms and formulae to calculate the alcohol by volume of every batch.
What is Brix?
A Brix value is expressed in degrees Brix. (°Bx) and defined as the amount of sucrose in grams present in every 100 grams of liquid.
The value of this parameter can range from 1 to 100 and is useful in the calculation of approximate alcohol content by simply multiplying it by 0.59.
For instance, if a pre-fermented liquid measures 10 Bx, its potential alcohol content would be 5.9.
