specific gravity issues

I've been brewing (from extract) for close to a year now and have managed to make a lot of good batches in a variety of styles. The problem I seem to have is that my specific gravity measurements for og or fg never make any sense at all.

For instance, this weekend, I basically followed a recipe for a high gravity Wee Heavy Scotch ale which called for 6 lbs dry extract and 6.6 lbs extract syrup. I boiled for 60 minutes, topped off to 5 gallons, allowed to cool, and took a measurement with my hydrometer. I got something like 1.040 (estimates from the recipe and confirmed using beer calculator should have been 1.090+ range). This happens frequently. I made another high gravity brew a few months ago and if you believe the calculations, it was 2% abv; trust me, it wasn't. My hydrometer is calibrated properly, I have been making the adjustments for temperature. I have no idea why my measurements seem so off. Any suggestions or tips? I mean, the beer I make is good, so I'm not sweating it too much, but I am puzzled.

Thanks!

You're probably not mixing the wort well enough before you take your OG measurement.

+1. You must stir the wort vigourously in the fermenter to mix the top-off water with the concentrated wort. Sugar is heavy; it sinks. So if you really stir the crap out of the fermenter and take the gravity sample while it's still spinning, you should get a credible gravity reading.

Cheers,

Bob

Thanks! Sometimes it's the simplest solutions...

I appreciate the quick help.

I'm just kind of asking to double check and be sure I have this right since I believe this is what happened to my last batch. My procedure for combining the wort and top-off water is as follows: I chill 2.5 gallons of water in my freezer a few hours before I brew. I pour this water in to the carboy and then add my wort, then I add a little more water to top it off to 5 gallons. After this I take my gravity reading.

Now, my question is that the pouring action of the wort in to the top-off water is not sufficient enough to fully mix the two together to obtain an accurate OG reading, correct? Hopefully next time I can get this right so I can know what my abv is of my beer because I'm pretty sure my latest batch is more than 2.9% abv.

You really have to do quite a bit to mix the wort and water with a partial boil.

The good thing is, it doesn't actually matter very much. Fermentation will mix it up just fine, and if you're using extract, your gravity is going to be pretty much dead-on whatever software tells you (you may have to adjust it slightly to account for specialty grains).

nalevai said:

Thanks! Sometimes it's the simplest solutions...

I appreciate the quick help.

Click to expand...

It's amazing how reluctant liquids can be to mix without outside interference. Even in the ocean you'll see precisely defined strata of temperature and salinity, all flowing this way and that, without mixing.

I used to do bar bets where I'd take two shots, one of whiskey to the brim, the other of water to the brim, and make them change places using naught but a business card. I'd put the card on the whiskey, lay it on top of the water, and pull the card out just enough so that the whiskey and water could slowly exchange places. Then I'd take the shot of whiskey I just won, and drink it down.

TheFlatline said:

I used to do bar bets where I'd take two shots, one of whiskey to the brim, the other of water to the brim, and make them change places using naught but a business card. I'd put the card on the whiskey, lay it on top of the water, and pull the card out just enough so that the whiskey and water could slowly exchange places. Then I'd take the shot of whiskey I just won, and drink it down.

Click to expand...

I would like to see a video of this!

Ask and you shall receive:

[ame]http://www.metacafe.com/watch/405950/bar_trick_with_whiskey_and_water/[/ame]

Austin_LSU said:

Ask and you shall receive:

http://www.metacafe.com/watch/405950/bar_trick_with_whiskey_and_water/

Click to expand...

It's been years since I did this, but the video is dead on. Whiskey is lower density than water and needs to be on the bottom.

I'm glad I didn't try this backwards. I would have been the ass end of jokes.

If you noticed, there's only a *tiny* little slit through which the fluids can exchange. It takes time, but this prevents the two from mixing. However, this video is an excellent visual example of why you *need* to stir the crap out of your wort before pitching yeast.

I brewed again this weekend and really stirred the wort after topping off, and the gravity turned out about where I was expecting (which was good too because it was my first partial mash, so I guess that worked out!). Like I said before, obvious solutions...

Thanks for everything everybody. And that video is sweet.