Post mash gravity to OG measurement.
  • BenvarineBenvarine
    Posts: 1,606
    The past few brews I've checked the post mash gravity to estimate my OG and it seemed on target, then when I finished the boil I ended up missing my gravity. I'm screwing something up. How do you determine if you got enough out of your mash to warrant adding DME before the boil?
  • JayrizzleJayrizzle
    Posts: 90,049
    So you're landing low?
    "I don't have TP, but I do have ammo."
    -Some guy in Ohio
  • Evan_BEvan_B
    Posts: 312
    Keep in mind that your boil is also a piece of the puzzle that contributes to the overall efficiency (Brewhouse efficiency, or whatever its called). If you aren't getting sufficient evaporation during your boil, your gravity will likely come up a bit short. This is usually were my efficiency suffers with each of my batches.
    Amigo, lay them raises down.
  • ThymThym
    Posts: 121,586
    you have to have really accurate gravity and volume measurements pre-boil to calc the mash efficiency or to start estimating what the final efficiency should be.

    Ben, share some numbers and we might be able to help point you to where you are losing efficiency.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • ThymThym
    Posts: 121,586
    also, temperature and stratification play huge roles in gravity readings. do you stir the transferred wort before the readings? what tool are you using to measure gravity? is it calibrated? at what temp?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    I'm coming up short, but with that said I'm changing my grain grind this weekend to see if that helps. I use a hydrometer, it is calibrated and I correct for temp. I've confirmed thermometers are accurate cold and hot to confirm mash temp. I use a ruler that I have calibrated for the kettle volume, it might not be exact because I did it with cold water not hot. Best I can do and I don't think it's going to be too far off. I don't end up with too much boil off, usually my finally volume is accurate. Just not getting enough efficiency. The last few batches I got 65%. I used that in beersmith and tastybrew for my last batch, mashed 90 min and was close, but two points low.
  • BenvarineBenvarine
    Posts: 1,606
    The formula I use to determine post boil gravity at pre boil is: gravity units measured * volume in gallons/final volume (estimated). So for instance, I brewed a IIPA, pre boil was 1.049 w/10 g. 49*10/5.5= 89. Target was 1.081, so over. Post boil gravity measured was 1.054. I working on my efficiency issues, but I want to know how to get an idea of how close I am after the mash so I can compensate then, not just deal with it at the time to pitch. And, is the formula I'm using wrong, or is something going drastically wrong, or am I measuring something wrong?
  • FuzzyFuzzy
    Posts: 49,655
    There has to be something wrong with the measurements. It's just not possible to cut the volume in half and only increase the gravity by 5 points like that.

    Is there a lot of sediment junk floating around in the sample? I've had some hydro readings that were impossibly high for the amount of grain I mashed.

    Also, are you stirring the wort up to mix it well before taking the sample?
    The pinnacle of lame and awesome in one singular moment. -Lake
  • JayrizzleJayrizzle
    Posts: 90,049
    What fz said. Once you get everything out of the mash give it a good stir and pull a a sample. Leave that on your counter. Junk will settle, wort will cool, then you get a good reading... Just dump it back in before the end of the boil.
    "I don't have TP, but I do have ammo."
    -Some guy in Ohio
  • ThymThym
    Posts: 121,586
    are you using a lot of top off water after the boil?
    The only thing between me and a train wreck is blind luck..... - Kenny
  • BenvarineBenvarine
    Posts: 1,606
    No top up water. There is a lot of break material floating around. I stir it prior to sampling. Should I let it settle first before taking a reading? Is it okay if it settles in the hydro tube with the hydrometer or do I need to decant?
  • C_BC_B
    Posts: 88,438
    Benvarine said:

    No top up water. There is a lot of break material floating around. I stir it prior to sampling. Should I let it settle first before taking a reading? Is it okay if it settles in the hydro tube with the hydrometer or do I need to decant?


    It's fine in the hydro tube as long as the break material is below the hydrometer.
    "On it. I hate software." ~Cpt Snarklepants
  • ThymThym
    Posts: 121,586
    C_B said:

    Benvarine said:

    No top up water. There is a lot of break material floating around. I stir it prior to sampling. Should I let it settle first before taking a reading? Is it okay if it settles in the hydro tube with the hydrometer or do I need to decant?


    It's fine in the hydro tube as long as the break material is below the hydrometer.

    correct
    The only thing between me and a train wreck is blind luck..... - Kenny
  • JayrizzleJayrizzle
    Posts: 90,049
    Also take your readings under 110f and adjust for temp. Above that tings get odd because lots of other junk can be in suspension. The closer to 60 the better.
    "I don't have TP, but I do have ammo."
    -Some guy in Ohio
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