Extract kit OG wildly off

[shoengine]

This is the second time I've had a kit be far off the mark for its original gravity measurement. First, my process:

1. calibrate hydrometer: measures at ~1.000 with just water.
2. After cooling wort, poured into glass carboy with 2 gallons of water, then adding water up to 5gal.
3. Siphoned out sample. Drop in hydrometer, shows 1.043 when expected OG is 1.063.

The last batch I did, a brewer's best IPA, measured at 1.040 and should have been around 1.060. Is this an issue with my process or water quality?

 

[bucketnative]

Did you stir the wort well in the fermenter after adding you top off water? It could be poorly mixed.

 

[shoengine]

No, I poured the wort into the water and then topped it off with the faucet. I shook it after I added the yeast, but I took the gravity before adding the yeast. It looked fairly aerated (about three inches of foam was above the liquid). I supposed it is possible. Should I take another gravity measurement even though the yeast is added? As of this morning (T+7 hours) no sign of fermentation has appeared.

 

[flars]

I don't bother with an OG measurement when doing a partial boil anymore. It is near impossible to get an accurate SG because the boiled wort and top off water will not mix completely. I use the recipe OG. When all of the extract is used and the volume in the fermentor is correct the OG will be that of the OG stated for the recipe.

The yeast will do a thorough job of mixing after active fermentation begins.

 

[andycook]

Are you adjusting for wort temp when measuring OG? What temp is your wort? There are calculators that adjust for temp.

 

[shoengine]

Thanks for the info. With kits they always give instructions for partial boils, and probably because it is less onerous to boil and to chill, but would there be any issues doing a full boil with extract or would that throw off the chemistry?

 

[shoengine]

Are you adjusting for wort temp when measuring OG? What temp is your wort? There are calculators that adjust for temp.

That is a good point I didn't take into account. The fermometer was showing 73•F and the OG was calculated at 60•F.

Edit: according to this calculator that only accounts for a thousandth of deviation, which is within an error margin for my style of hydrometer.

 

[SlitheryDee]

My first full 5 gallon batch was a cream ale extract kit. I was missing my hydrometer (came in broken) when I brewed, so I saved a bit of wort in a sanitized container after aerating to ensure that what I was saving was well mixed. Eventually when I got a working hydrometer I took the sample out of the fridge, let it warm up to 60 degrees, and tested it. I measured an OG of 1.048, which was only .001 off the expected gravity of 1.049, so I'm guessing I came out ok.

Based on that I would suggest that you take your sample for a gravity reading post aeration because then the wort will better mixed.

 

[shoengine]

I'll try that next time. Hopefully that is the case.

I should take a gravity on my IPA now that fermentation has been stilled for a few days.

 

[thekraken]

Yep, as others have said it just sounds like your sample wasn't thoroughly mixed. If you have X lbs of extract in Y gallons of water you get a gravity of Z, it's pretty full proof. So as long as the weight in extract you used was correct and you are confident in your fermenter's volume marking calibration then you should have the right OG... unless there was a typo or error in the recipe's OG calculation. You can always double check that by quickly plugging in the recipe into a brewing software.

 

[shoengine]

I'll do that.

For the IPA (which was the 1.040 sample) I guessed at the volume based on the not-so-perfect markings so I chalked it up to my volume being off. This time I was using a new 6.5 gal carboy as the primary, so I took my bucket, measured out 5 gallons exactly into the carboy, and then I marked the 5 gallon line, which is why I thought the result was odd.

Next time I'll mix it up with a paddle or something and then rehydrate the yeast after mixing which will give the wort an extra 30 minutes to assimilate.

 

[freisste]

....but would there be any issues doing a full boil with extract or would that throw off the chemistry?

No issues. In fact, in general I would say it is better practice if you have the means and time (longer to wait until boil starts, longer cooling time).

You will get less extract darkening and better hops utilization. Take hops into account as your cream ale could theoretically become a session IPA. Not really, but hops will be more noticeable.

 

[shoengine]

Just picked up this set off craigslist for $170. Had been stalking it for a week or so, so I think my next one will be a full boil!

 

[cswis86]

Damn that looks nice for $170!