Gravity error

[mikeljcarr]

I'm starting to loose all faith in my specific gravity measurements. I just brewed my second batch (a strong ale) and this time OG was high, 1.082 vs the recipe 1.070ish. I figured I just got more wort than water. It's sat in the primary for 3.5 weeks and I just bottled it and the FG was 1.031 vs recipe 1.020ish. I did have a pop off of the air lock before I learned to put on a blowoff drain, but it didn't look like I lost that much beer that it would have an impact, and following the pop off, fermentation continue strong for another 18 to 24 hours. Is my hydrometer off or am I doing something wrong? The first brew I did turned out OK, but it doesn't taste like it has a high alcohol content.

 

[Revvy]

I have a thread all about it...

Attention new brewers, yes your original gravity reading is wrong. Don't panic.

 

[BrewKnurd]

Check your hydrometer in distilled water. If it reads 1.000, its right.

As for your strong ale, if your OG was high, makes sense that your FG would also be high. Was it extract/partial mash/all grain? did you end up with the expected volume?

 

[mikeljcarr]

Thanks. I had read this before and it makes perfect sense for the OG, but why is my FG not getting where it should be?

 

[mikeljcarr]

It was partial mash and I ended with exactly 5 gals ( I've marked my carboy). I did recently learn though that I was making a mistake by boiling the wort covered. I've been brewing on an old stove in the basement and the only way I can get a good boil is by covering it. Would that have any affect?

 

[Revvy]

The former has nothing to do with the latter, those are two separate issues.That have nothing to do with each other.

That's what is known as the 1.020 curse, where a lot of extract batches tend to peter out at that point. Making sure you have put in plenty of oxygen and yeast on brew day helps. But some beer seem to stick regardless. A lot of that I think has to do with wort caramelization, where both the process of making and boiling the extract produces or converts some of the sugars into unfermentable ones.

Making sure you pitch enough yeast and giving the wort plenty of oxygen usually help prevent that.

 

[BrewKnurd]

It was partial mash and I ended with exactly 5 gals ( I've marked my carboy). I did recently learn though that I was making a mistake by boiling the wort covered. I've been brewing on an old stove in the basement and the only way I can get a good boil is by covering it. Would that have any affect?

If it was partial mash, I tend to agree with Revvy's general explanation of poor mixing on the OG. As for your final gravity, the fermentability of the extract can vary based on manufacturer, that could be part of your issue there.

Boiling with the lid on will reduce your boil off, which would directionally decrease your OG, not increase it.

If the stove is your only option, i would boil a smaller volume, so that you can really get a good boil. But the best option would be to get a new heat source (i.e. propane burner) to get a god boil with full volume.

 

[Calder]

Not much detail; extract or AG. If extract, believe the recipe rather than hydrometer. If OG, then you had better efficiency than expected.

1.031 is high to bottle any beer. Per your numbers: 1.082 to 1.031 = 62% attenuation. 1.071 to 1.031 = 56% attenuation.

It may be done, but my advice is to drink them quick before they explode.

Different yeasts and different ingredients result in different beers, but my experience is that my beers finish between 1.000 and 1.015. My starting gravities are usually around 1.055, and have been up to 1.100.

 

[Calder]

That's what is known as the 1.020 curse, where a lot of extract batches tend to peter out at that point. Making sure you have put in plenty of oxygen and yeast on brew day helps. But some beer seem to stick regardless. A lot of that I think has to do with wort caramelization, where both the process of making and boiling the extract produces or converts some of the sugars into unfermentable ones.

This guy finished at 1.031 rather than 1.020.

But ..... You have a lot of good advice, but, with respect, I think you are wrong about the 1.020. Agreed there are a lot of new brewers that end up around 1.020. But there doesn't seem to be many experienced extract brewers who end up there. I brew partial mash and occasionally brew extract with no issues; I think anything over 1.010 to be a problem.

I think a lot of the problem is inexperience: Primarily aeration, temperature, and yeast pitching rates. There are a lot of more subtle issues too that could contribute, but I think these three are the main ones.

 

[Revvy]

This guy finished at 1.031 rather than 1.020.

BUT.....Although we call it the 1.020 curse, it seems that extract beers that get stuck AT EITHER 1.020 OR 1.030, seen both numbers myself, and on here quite often. SO, I stick by what I said.

It's not the number as much as the fact that many extract batches have the propensity to finish higher than they should