Lousy attenuation

[tboyer]

I'm a semi-serious brewer - all grain since 1990; dozen or so batches a year - but my one big failing has been recordkeeping. Yeah, I know I should, but I've always been lousy at it.

So last year I turned over a new leaf. Got a Misco Palm Abbe refractometer, and started keeping detailed notes. And the one thing I noticed is that my beer (IMHO) is pretty good, but my attenuation was absolutely miserable.

Last few batches: 16.0 OG, 9.8 FG; 17.7 OG; 9.6 FG; 19.3 OG; 11.9 FG; 14.4 OG; 8.3 FG

etc. So I did what any good geek would do - throw books and equipment at it.

Bought Chris White's yeast book. Started doing 2L starters. Bought an O2 tank. Added yeast nutrient. Carboy temperature control.

Nothing. Whether it's Safale or Liquid, no matter what I do, the attenuation is miserable.

I've got no idea what to look for next. Or - since I like the finished product - do I just shut up and drink?

Suggestions, insightful questions, or dope slaps appreciated...

Tim

 

[mcaple1]

what kind of gravity readings are those?

 

[PantherCity]

Make sure your thermometer is calibrated. If you are mashing everything too hot you would get a less fermentable wort.

 

[944play]

They are in brix (which is near enough makes no difference Plato). You need to compensate for the unfermented sugars to get SG.
http://seanterrill.com/2011/04/07/refractometer-fg-results/

 

[Calder]

Last few batches: 16.0 OG, 9.8 FG; 17.7 OG; 9.6 FG; 19.3 OG; 11.9 FG; 14.4 OG; 8.3 FG

Tim,

If I read this right, this is really awful. I would get an hydrometer and check these readings are correct.

If your beer is 'pretty good', these numbers are not correct.

I'm assuming this is Plato, and your results are:

1.064 to 1.039
1.071 to 1.039
1.077 to 1.048
1.058 to 1.033

All are less than 50% attenuation, and would be very sweet tasting beers. I can't believe any beer that ends at 1.048 could be called 'pretty good'. I think your measurement could be off.

 

[osagedr]

You aren't trying to use your refractometer to get FG readings, are you?

If so...problem solved. Get a hydrometer.

 

[BrewKnurd]

You aren't trying to use your refractometer to get FG readings, are you?

If so...problem solved. Get a hydrometer.

To elaborate on this... the alcohol throws off the ability of the refractometer to accurately measure gravity.

 

[tboyer]

Tim,

If I read this right, this is really awful. I would get an hydrometer and check these readings are correct.

If your beer is 'pretty good', these numbers are not correct.

I'm assuming this is Plato, and your results are:

1.064 to 1.039
1.071 to 1.039
1.077 to 1.048
1.058 to 1.033

All are less than 50% attenuation, and would be very sweet tasting beers. I can't believe any beer that ends at 1.048 could be called 'pretty good'. I think your measurement could be off.

Me, either. That's what's confusing me. It ought to be undrinkable...

 

[944play]

Refractometers don't measure specific gravity, they measure sugar content. Roughly. Check out the seanterrill.com link above for a conversion formula and spreadsheet to ballpark a SG from a post-ferment refractometer reading and OG (whether from refract or hydro).

 

[tboyer]

To elaborate on this... the alcohol throws off the ability of the refractometer to accurately measure gravity.

Aha! So 'dope slap' was the right answer!

I had no idea a refractometer did not work with FG. That's the hint I needed. Thanks very much, everyone...

 

[944play]

Sean's spreadsheet shows ADFs of 66, 74, 62, and 70% for your four batches.

 

[1MadScientist]

I use this free one on the web with great results.

http://brew.stderr.net/refractometer.html

 

[bigbeergeek]

One of these threads pops up ever couple of months. Always satisfying to see the light come on.

 

[1MadScientist]

You're probably mashing at too high a temperature, 158 - 160* F +

 

[bigbeergeek]

You're probably mashing at too high a temperature, 158 - 160* F +

No. He wasn't adjusting his refrac readings post fermentation and getting artificially high SG readings.

 

[C-Rider]

Here is a link to convert Brix to SG

http://www.boulder.nist.gov/div838/SelectedPubs/Circular%20440%20Table%20114.pdf

And as stated you need a hydrometer to read FG.

Using the refractometer I've noticed a signifucant rise in reading the longer I wait before closing the cover which lets the few drops really cool off. Living in Hawai`i, my room temp during the day is about 80*. I'll never get it down to 60* where I under statnd the meter is calibrated for.

 

[1MadScientist]

So what are you guys saying about the link I posted and others on the net such as Morebeer's spreadsheet, are their formulas wrong? Are they all wet? I think refractometers can be used to measure terminal gravity just fine.

Would you agree or disagree that my last brew readings of;
17.2 Brix starting
9.2 Brix ending

was a 1.071 and a 1.015 and an attenuation of 79%?

 

[BrewKnurd]

So what are you guys saying about the link I posted and others on the net such as Morebeer's spreadsheet, are their formulas wrong? Are they all wet? I think refractometers can be used to measure terminal gravity just fine.

Would you agree or disagree that my last brew readings of;
17.2 Brix starting
9.2 Brix ending

was a 1.071 and a 1.015 and an attenuation of 79%?

I don't think anyone was saying that, just that you can't use the refractometer for final gravity without adjusting it, using something like the link you provided.

 

[bigbeergeek]

I don't think anyone was saying that, just that you can't use the refractometer for final gravity without adjusting it, using something like the link you provided.

Correct... and a FG of 1.015 doesn't imply he's mashing at >160*F, either.

 

[1MadScientist]

I absolutely get it now. I remember when I was a newbie, I started out with a refractometer and didn't understand the reading I got for my final gravity and threw that batch down the drain. ... second batch had a similar reading... I ended up bringing a pint of it to our club brew and perchance a member brought a hydro and it measured out to a good reading.

They are in brix (which is near enough makes no difference Plato). You need to compensate for the unfermented sugars to get SG.
http://seanterrill.com/2011/04/07/refractometer-fg-results/

Thanks for that spreadsheet. I like it over the other one I use.

 

[tboyer]

Sean's spreadsheet shows ADFs of 66, 74, 62, and 70% for your four batches.

Great. Bad attenuation is much better than horrible attenuation...