I never took an OG reading, what can i do to get alcohol %?

[nerdlogic]

as some of you already know-- i never took a hydrometer reading and everyone gave me real great advice on what to do next time. but what can i do this time to at least get the alcohol % of my brew?

Why can't I just take a sample, drop my hydrometer in it-
and look at the conversion chart that came with the hydrometer,
heres an excerpt from that table.

1.025 Specific Gravity = 3.2% alcohol
1.030 Specific Gravity = 3.9% alcohol
1.035 Specific Gravity = 4.5% alcohol
1.040 Specific Gravity = 5.3% alcohol
1.045 Specific Gravity = 5.8% alcohol
1.050 Specific Gravity = 6.4% alcohol
1.055 Specific Gravity = 7.3% alcohol

I could repeat this over 1-2 days and take the average possibly?

 

[david_42]

Because those readings are POTENTIAL values based on OG and have nothing to do with the actual ABV. ABV is based on the amount of sugar fermented, OG -FG.

If this was an extract batch, use their OG value.

 

[Sir Humpsalot]

Specific gravity is a relative reading. It's not the actual number you care about, it's the difference between the number when you started and the number when you finished.


Let's say you started with an original gravity of 1.047 and finished with an ending specific gravity of 1.012. The difference between those numbers is .035 and that is what you need to calculate the level of alcohol. This example yields 4.6% ABV.

 

[Baron von BeeGee]

Just post your recipe and somebody can probably tell you what the OG should have been.

 

[Sir Humpsalot]

Right now my lager is sitting with a specific gravity of 1.036. Once it reaches around 1.020 or so, it'll be ready for cold storage (lagering). Until then, I know there are still fermentable sugars in there that can and should be converted to sugar.

How do I know? Because my potential alcohol level (specific gravity) is too high. It should be below 1.020 (for most beers). So I am fiddling with extra yeast and aeration and stuff, trying to get the final gravity down (and increase the difference between the initial gravity and final)

 

[Sir Humpsalot]

Here's my ballpark method for when you don't have your chart handy. Let's say your brew has an OG for 1.090 and an ending SG of 1.010. That's a difference of 0.080.


1. Move the decimal place over one so you have --> .8

2a. Multiply that number by 3 so you have --> .8*3=2.4
2b. Divide that number by 3 so you have ----> .8/3=.267
2c. Now add them together to get -------------------->2.67

3. Move the decimal place over one more time --> 8.0

4. Add the answer from #3 to #4. So you get 2.67 + 8.0--> 10.67




According to promash, the correct answer is 10.64

 

[lefteye]

Note to self: keep chart handy

 

[Yuri_Rage]

Here's a different chart:

Drink a six pack of your beer in under two hours.
Still standing upright with no perceived effects: 0.0% - 2.0%
Happy for no apparent reason, speaking loudly: 3.0-4.0%
Drunk dialing all of your friends: 5.0%-6.0%
Seeing recent pictures of Britney Spears and thinking "She's hot:" 7.0%-8.0%
Actively looking up recent pictures of Britney Spears because "She's hot:" 8.0%-8.5%
Failing to find those Britney Spears pictures because you can no longer spell Britney: 8.5%-9.0%
Need another cold beer and can't get one because you're seeing at least two fridges where there should just be one: 9.5%-10.0%
Passed out on the floor, curled up with the dog: 10.5%-11.5%
Passed out next to the toilet, failing to flush whatever you last put into it: Greater than 12.0%

 

[Whelk]

Here's a different chart:

Drink a six pack of your beer in under two hours.
Still standing upright with no perceived effects: 0.0% - 2.0%
Happy for no apparent reason, speaking loudly: 3.0-4.0%
Drunk dialing all of your friends: 5.0%-6.0%
Seeing recent pictures of Britney Spears and thinking "She's hot:" 7.0%-8.0%
Actively looking up recent pictures of Britney Spears because "She's hot:" 8.0%-8.5%
Failing to find those Britney Spears pictures because you can no longer spell Britney: 8.5%-9.0%
Need another cold beer and can't get one because you're seeing at least two fridges where there should just be one: 9.5%-10.0%
Passed out on the floor, curled up with the dog: 10.5%-11.5%
Passed out next to the toilet, failing to flush whatever you last put into it: Greater than 12.0%

Most useful chart ever.

 

[nerdlogic]

So theres no way without an OG?

my recipe is:

6 LB "Home Brewery (TM) Malt Extract, Unhopped Light"
1 LB Cara-pils
4oz Saaz Hops (DOES HOP TYPE MATTER?)
5 gallons of water

 

[Yuri_Rage]

So theres no way without an OG?

There is...but you need REALLY expensive equipment to analyze it.

I'm away from home, so I don't have my brewing software handy. Someone will figure your predicted recipe outcome and post it, though.

I highly recommend getting a hydrometer and using it correctly if you're that concerned about ABV. Also, BeerSmith is excellent software for recipe creation/modification/estimation.

 

[Sir Humpsalot]

Was that liquid extract or dry extract? I assume it was liquid?

Do you still have 5 gallons of beer? Or was that 5 gallons pre-boil? If it was preboil, we need to know how long you boiled it for so we can make an estimate about evaporation.

No, hop type doesn't matter one whit.

I am also assuming the carapils was steeped, not mashed. Is that correct?

But assuming you have 5 gallons of beer and you did not do a partial mash with the grains, but only steeped them in water like a tea, and further assuming that cheesefood's wife likes bukkake, an estimate of your S.G. with 6 lbs of liquid malt extract, according to ProMash, is 1.037.

 

[Sir Humpsalot]

There is...but you need REALLY expensive equipment to analyze it.

Awww come on.. I've seen brix refractometer thingies for under a hundred bucks. You saying those don't work?

 

[Yuri_Rage]

Awww come on.. I've seen brix refractometer thingies for under a hundred bucks. You saying those don't work?

Bet they work pretty well, but they still just measure specific gravity, so you'd need to measure OG and FG just as you would with a hydrometer. To analyze just the finished product for ABV requires some pretty high tech lab equipment.

 

[Sir Humpsalot]

Bet they work pretty well, but they still just measure specific gravity, so you'd need to measure OG and FG just as you would with a hydrometer. To analyze just the finished product for ABV requires some pretty high tech lab equipment.

Ahh.. you're right. Got my head all turned around on that one.

 

[Sir Humpsalot]

Ok man.. we've got your ballparked OG of 1.037.

Now what's your current, finished, gravity?

 

[nerdlogic]

STEEP 30 MIN:

1LB Cara-pils
2.5 Gallons Water

BOIL 60 MIN:

6 LBS of HomeBrewery.com unhopped Light Malt Extract (Very Gooey)
4 oz of Saaz Hops added just about every 15 min.

I ended up with about 5 gallons once I increased the volume with water.

Chilled and then pitched 12 grams BREWFERM lager yeast

 

[The Pol]

Unless you know your efficiency precisely... well, pray to the beer Gods.

The Pol

 

[Sir Humpsalot]

Unless you know your efficiency precisely... well, pray to the beer Gods.

The Pol

It's an extract kit. efficiency doesn't matter much unless you're talking about the residual sugars from the steeping, but I doubt those contribute much at all.


Now, nerdlogic, go measure the CURRENT gravity of your brew.

 

[nerdlogic]

I pitched the yeast last saturday (2/10/07) --

its still bubbling once every 8 seconds or so,
i should take a reading now?

 

[Orfy]

Yes......

If in doubt take a reading. If not don't.

 

[nerdlogic]

i doubt of what? im so excited to take a reading but i want to make sure i'm not jumping the gun.

 

[Orfy]

If you're in doubt if it's finished, if it's stuck, if it's nearly done, if it's ready to go to secondary. Then take a reading
If not in doubt don't bother.

Unless you just want to then do.
It's good for QA to sample, especially whilst you are learning.

 

[nerdlogic]

Ok i took a reading

1.010 so far

i resealed it and its back to bubbling once every like 10 seconds

i figure i should give this 2-3 more days

the krausen did drop a lot since yesterday
but i did lower the temperate from 58 to 56 to let it lager better

it sure smells something like beer

should i drink the sample?

AWAITING SUGGESTION

 

[Yuri_Rage]

Unless it smells like feet or puke, ALWAYS drink the sample. If it smells so bad that you can't sample it, wait a week or two before you even contemplate throwing the batch away!

 

[nerdlogic]

I drank it, it meets the target taste range but its not carbonated... mmmmmm

 

[Sir Humpsalot]

So according tomy formula, that's 3.6% ABV and still going.

 

[Orfy]

1037-1010= 27/.76= 3.6% ABV (aprox)

It shouldn't drop much moor than 1008/1010 or if it does you'll and up with a BMC style beer.

 

[Kaiser]

If this was an extract batch, you will be able to estimate your OG reasonably well.

But to answer your initial question, yes one can determine the alcohol content of the beer by examining a post fermentation sample only:

measure the apparent FG on the sample of beer by measuring the FG as you would normally do it.

measure the true FG on the sample by boiling off the alcohol and replacing it with water. This is simple. Just fill your hydrometer flask with the beer to be tested and mark the level. Now boil this sample in a small vessel until you are sure all the alcohol is out. cool and fill it back into the flask and top off with water until you have the same volume again. You can use some of the water to rise the left-over sugars from the boiling vessel. Now mix well and measure the actual FG on this sample. The actual FG should be higher than the appearent FG.

Now you can determine alcohol and OG with a formula that I would have to derive from the relationship actual attenuation = 0.8 * appearent attenuation.

The same could be done by taking a hydrometer and a refractometer reading of the sample. But a different formula would have to be used for that.


But due to errors in the measurement of the gravities with a simple home brewing hydrometer it may be more acurate to estimate the OG and deterine the alcohol content via the conventional way.


Kai