My science head says this is impossible, but my last two brews have seen me lose or gain no gravity during my boil.
Today I had a pre-boil gravity of 1.046 and a post boil gravity of 1.046 (75-minute boil with pre- and post-boil volumes hit (29l down to 20l). The previous brew saw pre-boil gravity of 1.034 and a post boil of 1.033. The obvious questions: yes, I triple checked my figures and am absolutely certain they reflect what I sampled. I take the pre-boil gravity reading from the kettle after sparging, and before doing so I stir the wort with the wine thief that I use to extract the sample. I then chill the sample to 20 degrees Celsius and take a hydrometer reading. Post-boil I wait until I transfer the wort at pitching temp into the hydrometer and again take a hydrometer reading (from the fermenter) after stirring. The hydrometer is out by about 1 point from water calibration, but that shouldn't be an issue here. I always do temperature corrections on my hydrometer readings.
I have begun using a hop spider, and there's a fair bit of crap left in it when I end the boil. Could that be taking sugars away?
I leave about a litre of crud in the bottom of the kettle when transferring to the fermenter. Could that be ultra sugary and preventing those sugars from hitting the fermenter?
Finally, I suppose that by stirring with the wine thief I could be taking most of the sample from unstirred wort that has gone into the wine-thief while stirring, but surely the sugar is evenly in solution after 75 minutes of boiling and 20 of cooling? Also, the error should cancel out by giving me similarly lower than reality pre-boil and post-boil readings (that is, they should both be lower than reality if all I'm getting is unstirred wort), but still not the same reading both times.
Interestingly, I missed my Beersmith-calculated post-boil gravity by 6 points but hit the published post-boil gravity (I was following a recipe from the Jan/Feb 2018 BYO). Probably a question for another day as to why Beersmith's calculations were so far out!
Any advice appreciated!
Cheers
Az
Today I had a pre-boil gravity of 1.046 and a post boil gravity of 1.046 (75-minute boil with pre- and post-boil volumes hit (29l down to 20l). The previous brew saw pre-boil gravity of 1.034 and a post boil of 1.033. The obvious questions: yes, I triple checked my figures and am absolutely certain they reflect what I sampled. I take the pre-boil gravity reading from the kettle after sparging, and before doing so I stir the wort with the wine thief that I use to extract the sample. I then chill the sample to 20 degrees Celsius and take a hydrometer reading. Post-boil I wait until I transfer the wort at pitching temp into the hydrometer and again take a hydrometer reading (from the fermenter) after stirring. The hydrometer is out by about 1 point from water calibration, but that shouldn't be an issue here. I always do temperature corrections on my hydrometer readings.
I have begun using a hop spider, and there's a fair bit of crap left in it when I end the boil. Could that be taking sugars away?
I leave about a litre of crud in the bottom of the kettle when transferring to the fermenter. Could that be ultra sugary and preventing those sugars from hitting the fermenter?
Finally, I suppose that by stirring with the wine thief I could be taking most of the sample from unstirred wort that has gone into the wine-thief while stirring, but surely the sugar is evenly in solution after 75 minutes of boiling and 20 of cooling? Also, the error should cancel out by giving me similarly lower than reality pre-boil and post-boil readings (that is, they should both be lower than reality if all I'm getting is unstirred wort), but still not the same reading both times.
Interestingly, I missed my Beersmith-calculated post-boil gravity by 6 points but hit the published post-boil gravity (I was following a recipe from the Jan/Feb 2018 BYO). Probably a question for another day as to why Beersmith's calculations were so far out!
Any advice appreciated!
Cheers
Az
