I am still extract brewing due to the fact that my funds will not allow me to advance at this point, but the last 2 batches of beer I have brewed are shockingly low as the OG is concerned. After primary fermentation my FG is hitting the points where I expect but the OG is leaving me scratching my head. Is there some rookie mistake I'm making during my boil that I am overlooking? I know coming short on gravity is not uncommon, but I am coming up very short.
It's pretty hard to not hit the OG with extract. These Possibilities (alone or in combination) come to mind (actually they come from one of my older posts)... 1) The kit was short on extract 2) Not all the extract made it into the kettle 3) You topped off with water to more than 5 gallons (if not a full boil) 4) You didn't mix the top-off water with the wort thoroughly before measuring the OG 5) You did a full boil but didn’t boil down to 5 gallons. 6) You measured the OG while the wort (and top off water if applicable) was still hot, and didn't adjust the reading for temperature. 7) Your hydrometer is inaccurate (try checking it with plain water) 8) You read the hydrometer wrong. But since your FGs seem to be exactly what you were expecting, that would narrow the possibilities down to #4, #6, and/or #8. If not one or more of these theree things, then it's more complicated, because attenuation would be something other than expected.
This happened to me a few times. My mistake fell under #5. I attributed to a less vigorous boil on a stovetop, I've since adjusted my water volume.
Is this from a kit or a recipe you designed? In other words is this a suggested OG from the kit or a calculated/estimated OG from whatever recipe your put together?
VikeMan's point 6 struck me when I was a beginner. Now I keep this page open every time I brew: http://dd26943.com/davesdreaded/tools/convert.htm
I think #4 must be it, not doing kits, I usually at some DME to adjust for the extract in the vessel that is left behind, all my other measurements are spot on and I never measure take measurements until I'm ready to pitch my yeast. Thanks for the help, I never really thought about #4 but it makes perfect sense, so should I basically assume that my OG is going to be close to what I had estimated if this is the case because I did make sure to oxygenate the wort prior to sealing.
I would agree with all of the suggestions from vikeman, the only other suggestions i could add would be to check your calculations for OG, and to make sure you are consistent with your boil volume and boil time. A basic estimation i used to use with DME was to assume ~1% increase in abv for each lb of extract used.
Good rule of thumb for most dry extracts. More like 0.0072 for liquid extracts. I know you were answering within context. Just adding for the benefit of future googlers.
