Hitting Original Gravity

Physics, chemistry and biology of brewing. The causes and the effects.

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Hitting Original Gravity

Postby hangtendesign » Sat Mar 14, 2009 11:00 am

So I thought I had this down. I even nailed my pre-boil gravity of 1.046. Did my boil and got exactly the correct post-boil volume of 5 gallons. However..... my original gravity was 8 points more (1.069) than I wanted it to be using the software. Mind you, it tasted phenomenal and I'm sure it will just be great (nice big beer) but I'm trying to control my brewing so I can brew predictably to my constructed recipes.

Can anyone think of any variables that would cause this to happen?
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Re:Hitting Original Gravity

Postby Legman » Sat Mar 14, 2009 12:06 pm

Maybe your pre-boil volume was bigger than you though, even though you hit the pre-boil gravity.
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Postby hangtendesign » Sat Mar 14, 2009 5:00 pm

My pre-boil volume is always the same. My software is always set to that as well and is why I always hit my final volume.

Is it possible that the kettle collecting the extract from the mash is not fully mixed and is heavier on the bottom than on top? Hence, if I measure the gravity at the top it wouldn't be true? I don't know if that is possible.

I did a decoction to mash out to 168 degrees. Would that change anything? I don't know how it would.
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Postby Legman » Sat Mar 14, 2009 7:35 pm

I'm not a 100%, but it does seem like I've read that somewhere before. That may be the cause. Not sure.
I batch sparge and don't ever measure my pre-boil gravity. I'm just concerned with the post boil OG.
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Postby cozrulz » Sun Mar 15, 2009 4:01 pm

Have you tried repeating recipes? Maybe a variable is off in the software? See if you hit the same OG with the same recipe, then look at the variables.
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Temperature

Postby Skunk » Tue Nov 10, 2009 11:13 am

What temp is you wort when you measure your OG? Hydrometers are calibrated to take readings at 60 F and if it is above that say 77 F and you take your reading of say 1.046 then you need to make a correction by adding 2 so your actual OG would be 1.048. Unfortunately your wort would have to be about 115 F to need a correction of 9. Also if you think that the bottom is more dense you could stir it before you take a reading. I know in Barley Wine it is common to measure the runnings and watch them peak then stop when they come down between 1.048 and 1.036. This is to ensure it's a big beer and now watered down per say.
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