Make sure you stir well...

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Desp

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So today I came to a realization. Topping off your wort with water, putting the lid on and then shaking vigorously back and forth for 20 seconds, stopping, removing your finger from the airlock hole in the lid and resting, and then repeating the same process another 3 times DOES NOT STIR THE WORT!

I thought for sure aerating it like that would properly stir it, as it was very vigorous, but apparently not.

After brewing a barley wine tonight, and mixing it as previously described, I took a gravity reading by slowly lowering a measuring cup into the top of the wort. I poured that sample into my test tube and took the reading... 1.070... IMPOSSIBLE! The recipe predicted it at 1.094, since this was a mini mash even with NO conversion of the grains it still should have been 1.084, plus I added some extra dextrose. I concluded two possibilities... Either I added WAY to much extra water... or it's not mixed properly, that's the only possibility. Checked the total volume of wort and it was SLIGHTLY above where it should have been...

Sanitized my spoon and VIGOROUSLY mixed the wort in a circular motion, shook it some more, took another reading... 1.102, quite a difference. Bummer.. How many batches that I've brewed, but only shaking and splashing back and forth haven't been properly mixed... all of them? :(

Well, now I know. I think I'll get one of those motor mixing spoons for my drill and give that a go next time.
 
I wouldn't worry too much about it - sure, your OG reading might be off by a bit, but that's about all your trouble. Once fermentation kicks off, everything gets mixed up just fine.
 
I wouldn't worry too much about it - sure, your OG reading might be off by a bit, but that's about all your trouble. Once fermentation kicks off, everything gets mixed up just fine.

That's kind of what I figured, the fermentation process would probably still take care of mixing it up the rest of the way and eating all of the sugars, but I like to know what I'm working with, and maybe a few of my brews that had real low O.G. readings but still seemed really strong just weren't mixed properly and the reading was off.

I was just surprised that shaking it that hard didn't actually mix it, considering how much foam was at the top of the bucket and everything, yet somehow it wasn't mixed.
 
What you have described is a real problem in analytical science. Half of the battle sometimes is getting a sample that is representative of the whole.

While it may be surprising to learn, two liquids of different density can be quite reluctant to mixing. This even occurs in natural bodies of water (ie the meeting of two rivers or brine pooling in ocean trenches). People assume that it takes special care to "layer" liquids (like in those fancy bar shots), but that is not always the case.

Diffusion is not sufficient to ensure the complete mixing of two fluids of differing density. It is simply too slow.

You should always stir thoroughly before drawing a hygrometer sample, regardless of whether you believe there exists a gradient or not. Otherwise, you are flying blind and your measurements are suspect.
 
So today I came to a realization. Topping off your wort with water, putting the lid on and then shaking vigorously back and forth for 20 seconds, stopping, removing your finger from the airlock hole in the lid and resting, and then repeating the same process another 3 times DOES NOT STIR THE WORT!

I thought for sure aerating it like that would properly stir it, as it was very vigorous, but apparently not.

After brewing a barley wine tonight, and mixing it as previously described, I took a gravity reading by slowly lowering a measuring cup into the top of the wort. I poured that sample into my test tube and took the reading... 1.070... IMPOSSIBLE! The recipe predicted it at 1.094, since this was a mini mash even with NO conversion of the grains it still should have been 1.084, plus I added some extra dextrose. I concluded two possibilities... Either I added WAY to much extra water... or it's not mixed properly, that's the only possibility. Checked the total volume of wort and it was SLIGHTLY above where it should have been...

Sanitized my spoon and VIGOROUSLY mixed the wort in a circular motion, shook it some more, took another reading... 1.102, quite a difference. Bummer.. How many batches that I've brewed, but only shaking and splashing back and forth haven't been properly mixed... all of them? :(

Well, now I know. I think I'll get one of those motor mixing spoons for my drill and give that a go next time.

Yeah, a mixer on a variable speed drill. *drool*

I just need to get around to it. I could cool my wort in 10 minutes or less with it, but I never remember to actually buy it. Plus, in those situations where I boil off too much wort I'd be able to stir it so much easier.
 
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