Gravity question

Discussion in 'General Brewing Discussions' started by jeffpn, May 14, 2018.

  1. jeffpn

    jeffpn Well-Known Member

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    True enough!
     
  2. Nosybear

    Nosybear Well-Known Member

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    Agreed. The only reason it should stratify is if it weren't well mixed (which would happen over time). Sugar is so soluble it won't "settle" under normal conditions.
     
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  3. BOB357

    BOB357 Well-Known Member

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    My sample from the pump and hose has a lot of trub/break material suspended in it and takes a while to settle out to a degree that the hydrometer doesn't touch it. I see between 2 and 3 points difference in gravity after settling. Think of it like air bubbles in the wort with the opposite effect. Neither is in solution, but both affect the density because they share space with the solution.
     
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  4. jeffpn

    jeffpn Well-Known Member

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    Air bubbles would tend to make the hydrometer float by pushing it up. I could see where it could cause a false reading. What about that glitter beer? Who thinks glitter beer has a higher gravity than its non-glitter counterpart?
     
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  5. Beer_Pirate

    Beer_Pirate Active Member

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    I think that would definitely affect reading until it settles out (the first two pints had all the glitter). I didn't add glitter to SWAMBO's until packaging though so I don't have any data to back it up. There's no trace of it now aside from a pink tint left by the dye in the luster dust.
     
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  6. Trialben

    Trialben Well-Known Member

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    well as long as the glitter didnt come out of you in the TOILET:eek:! imagine that..
     
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  7. Hogarthe

    Hogarthe Well-Known Member

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    Depends which side the glitter came out into the toilet..... It could be very painful
     
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  8. Trialben

    Trialben Well-Known Member

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    yeah and that aint glitter:p:D!
     
  9. Mase

    Mase Well-Known Member

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    Maybe try an experiment... can you take an undisturbed sample from just above the settled trub and then take one near surface and compare the two?
     
  10. jeffpn

    jeffpn Well-Known Member

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    I’ve tried using the thief to get wort from the middle of the kettle, hoping it’d be pretty clear. It takes forever for my kettle to settle!
     
  11. jeffpn

    jeffpn Well-Known Member

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    We’ve talked about a snow globe before. Would the specific gravity of the water inside depend on whether the snow was suspended or settled? In my mind, since it’s not dissolved in the water, it doesn’t contribute to the density of the water.
     
  12. Beer_Pirate

    Beer_Pirate Active Member

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    Here's a nice math-y similarity from stack exchange. The scenario is a little different, since they're talking about a spherical buoy chained to the bottom of a tank, but it's some food for thought. The question itself makes the assumption that water with particulates (not in solution) has a higher density than water without.
     
  13. jeffpn

    jeffpn Well-Known Member

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    That’s a lot of math!
     
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  14. Beer_Pirate

    Beer_Pirate Active Member

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    Way too much for me (especially since the first equation would have to change since hydrometers aren't spherical)!
     
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  15. BOB357

    BOB357 Well-Known Member

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    OK, I brewed today and, as usual, took my sample for OG by draining the pump and hoses so there was a good amount of break material in it. I took the first hydrometer reading of 1.052 right after filling the hydrometer jar at 80 degrees F. My hydrometer is calibrated at 68, so the correction is +.0022. The second reading after the break settled to below the hydrometer was 1.051 at 70. The correction is + .0003. The difference with corrections applied was .0029, or just under 3 points.
     
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