Pre Boil and Original Gravity are the same!! Why?

[BigEasy43]

I just finished up an IPA and took a pre boil gravity reading and it came out to be 1.040 at 69F, after 60min boil and cooling down the wort I took another reading and it was 1.040 at 65F. Why is this? Did my boil not boil well enough? Any suggestions would be great because after 5 hrs today and getting to the end it's a little disappointing. This is the my second time doing the IPA and didn't have any issues first time around. Thanks

 

[BitterSweetBrews]

What kind of boil off did you have? If you had boil off there is no way the gravity is going to be the same. Are you sure the pre boil gravity reading was correct?

 

[BigEasy43]

I started with 6.25 Gallons and at the end I had about 5.5 gallons, so that's what I am confused. I am pretty sure the pre boil was right as I double checked it and compared my notes.

 

[RoadKing]

Did you cool the sample? I find that even with a refractometer, unless it cooled, the preboil gravity will be way off.

 

[jodell]

I did an IPA last hand had a similar issue

I actually had a pre-boil gravity of 1.072 and a post of 1.055.....

After some investigating I found that the slip of paper in my hydrometer had actually come loose,so the scale moved slightly everything I used it. Check that on yours because that is a sneaky problem

 

[McKnuckle]

There is absolutely no possibility that you didn't increase the gravity of your wort during the boil. So either: 1) The pre-boil sample was not adequately mixed, resulting in a too-high reading; or 2) You didn't correct one or both readings for temperature. Sounds like the latter is not a factor, so I'd go with the former. This happens to me all the time, despite stirring and trying really hard to combine layers of the pre-boil wort. It's truly a pain.

Based on your estimated volumes, you were at ~1.035 pre-boil, and evaporated about 0.75 gallons to reach 1.040 (at 60ºF).

 

[BigEasy43]

There is absolutely no possibility that you didn't increase the gravity of your wort during the boil. So either: 1) The pre-boil sample was not adequately mixed, resulting in a too-high reading; or 2) You didn't correct one or both readings for temperature. Sounds like the latter is not a factor, so I'd go with the former. This happens to me all the time, despite stirring and trying really hard to combine layers of the pre-boil wort. It's truly a pain.

Based on your estimated volumes, you were at ~1.035 pre-boil, and evaporated about 0.75 gallons to reach 1.040 (at 60ºF).

Yes I did stir to combine the layers of the pre boil wort as you said, but something had to be off to get my pre boil reading like that.

 

[jmark]

This is a common issue trying to mix the wort - the denser stuff, higher gravity stuff is at the bottom and it's difficult to get a homogeneous mixture even with stirring. What I've found works well is actually wait for the wort to start boiling and let the convection currents do the work... I'll basically do a 65 minute boil and after 5 minutes, take my pre-boil reading and add my first hop addition (if I've got a 60 min addition). My pre-boil readings are much more consistent since I started this regimen.

 

[JDXX1971]

I just started brewing with re-circulated BIAB and what I do is take the sample from the re-circulation. Three batches so far and all my #'s seem in order with BS. Not that I know what I am doing, but it seems to work for me.

 

[-CHRIS-]

Taking pre-boil gravity reading is a sure fire way to drive yourself batty. The aforementioned mixing issues are real. i used to drive myself nuts taking those measurements and finally stopped. i know the efficiency of my system and only take a final gravity reading in the fermenter to make sure it matches beersmith...it always does!

Final runnings are always a good thing to check.

Chris