Gravity Reading Error

[nyrmc23]

I just brewed my seventh batch and for first time I took notes on everything. So far, everything (outside of 2 batches) has been at worst decent and at best very good, so I thought I should start taking notes.

My pre-boil reading was 1.022 and my final was 1.044. Is this possible? I only ask b/c I popped it into some calculators online and I'm getting a negative percentage, so I'm thinking I did something wrong. Thoughts?

 

[nyrmc23]

I should add it's entirely possible I misread the hydrometer ha.

 

[BrewInspector]

Pre-boil will be lower than post boil which would be your original gravity (OG) followed by your again lower final gravity (FG) after fermentation.

These readings must also be temp corrected if using a hydrometer.

A refractometer can be used for pre-boil, post-boil, OG but is inaccurate once alcohol is present during and after fermentation. (there are correction calculators but they too are inaccurate over ranges)

Not sure what you are trying to do with a pre-boil reading and a final gravity (FG)...or did I misunderstand what you were saying?

You need the OG and FG to calculate alcohol content.

 

[nyrmc23]

Oh I thought the OG was pre and final was post. So when should I measure? Would my post-boil be my OG?

 

[grampamark]

Oh I thought the OG was pre and final was post. So when should I measure? Would my post-boil be my OG?

The pre-boil gravity is taken when all the wort is in the kettle and you are ready to start the boil. The OG is taken after the boil, the wort has been cooled to pitching temperature and you are ready to pitch the yeast. Final gravity is the last reading taken before bottling or kegging.

Hydrometers (at least the 8 dollar LHBS specials that most of us use) are calibrated for 60°F. Cool your samples to that temp before taking a reading.

 

[nyrmc23]

Thanks a lot!

 

[IslandLizard]

What kind of brews are these? Extract kits? All grain? What volume?

For example, it's much more likely to condense a 1 gallon batch from 1.022 to 1.044 than a 5 gallon one during an hour boil.
That said, 1.022 is a pretty low gravity to start with.

 

[ChaosB]

From what I understand, I'm still new at this.. your OG should be higher than pre-boil gravity due to the fact that during the boil, you will lose some volume of wort but the sugars remain, thereby raising the gravity of the remaining wort.

As for how much it should change, I'm not sure. My first brew I boiled off 1.5 gallons and my gravity changed from 1.066 to 1.086.

I started with 6 gallons in the BK and ended with 4.5. I had intended to end up with 7.25 gal pre-boil but both my efficiency / losses and boil off rate were off my estimated calculations for a new system.