Gravity going down during boil. How can it happen?

Can you think of any scenario (apart from errors of the measurement tools) where gravity actually goes down during boil. Normally, due to the loss of water, gravity should always go up. During our last brew session, we measured lower post-boil gravity (1.058) than pre-boil (1.068) and we're quite puzzled.

How we took the samples:

Pre-boil: pipette from top of stirred boiling pot.
Post-boil: pipette from first drawings after whirlpool.

Any ideas?

Topic gravity-reading boil homebrew

Category Mac

1
answered at

Bottom line: its impossible for the gravity to decrease during boil. You only evaporate water, leaving an increasingly sugary solution.

So there is an error with your preboil postboil or both gravity readings.

Most common reasons for incorrect readings:

  • Incomplete Mixings
  • Failure to to a temperature adjustment
  • Related to the second - Uncalibrated hydrometer
1
answered at

from where did you take the sample? I am guessing you hadn't stirred the wort before you took the sample from the bottom of the brew pot, where the gravity will be the highest.

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