sugar gnomes stealing from my wort

kmudrick · 10-15-2008, 01:02 PM

I've been experiencing this weird phenomenon lately where my gravity readings before and after boil don't jive.

Example: Brewed a pale ale this weekend

10# 2-row, 12 oz Crystal 60, 8 oz Carapils

My goal was for 7.10 gallons pre-boil, boil down to 6 gallons, transfer 5.5 to carboy.

60 minute mash @ 153. I mashed with 3.4 gallons of water. I used Five Star 5.2, a fairly good crush (.24mm gap on the barley crusher) and I am using a 10 gallon rubbermaid cooler as a mash tun and a stainless braid.

(Batch) Sparged with 5.6 gallons of water. Collected a little over 7 gallons. Stirred up the wort and checked the gravity twice - 1.030 @ 133 degrees, which calculates to 1.044. Great. 75% efficiency there (was targetting 1.041)

60 minute boil. Post boil volume was around 5.3 gallons. Whirlpooled and racked slightly more than 5 gallons to my fermenter. Measured gravity was 1.046 @ 79 degrees, which equates to 1.048.

Huh? How'd that happen? Boiled off almost 2 whole gallons... and only gained 4 gravity points?

This has happened probably 3 out of the last 4 batches I have done recently.

Theories I have:

1) The pre-boil gravity reading is waaaaay off via the temp correction formulas. Really? How else would I go about doing it, other than buying a refractometer, which I thought has to be temp-corrected too? Also - that would mean indicate efficiency is waaaay crappy, and I don't know what else I could do (sparging with lots of 170dF water, using the 5.2 ph buffer stuff, doing a fine crush) to correct that.

2) Sugar really is evaporating during the boil, or there are little gnomes and/or fairies stealing it while I am not looking.

3) [Far-fetched] I am usually using whole leaf hops.. Maybe they are really absorbing a ton more than I expect. This weekend's brew had 3.5 oz of flowers in the kettle.

Any other ideas/explanations would be, umm, much appreciated.

**conpewter** · 10-15-2008, 01:21 PM

I would go with #1 as I've heard that the temperature correction is not useful when far off of the calibrated temp. I'd take your preboil sample and set it in some icewater for a minute and then take your temp and reading closer to 60 degrees

EvilTOJ · 10-16-2008, 10:13 AM

So sugar gnomes are more likely than wort getting soaked up by your hops? mmmhmm.... He's probably laughing and dancing on his little feeties as well.

I would also suggest cooling the samples down to get a better measurement.

**ajf** · 10-16-2008, 12:26 PM

1 is absolutely true. Temperature compensation at that high a temperature is not reliable, but you can always cool the sample before taking the reading, and then put it back in the kettle (if you want) for the boil.
3 is also true. Whole leaf hops absorb a lot of wort. See http://www.homebrewtalk.com/f13/whole-hop-absorption-28263/#post278082
Other possibilities are:
4 You are ignoring all the losses associated with transferring to primary (dead space in kettle, trub, wort left in chiller etc.)
5 Your volume measurements may not be completely accurate
6 You did not stir the wort sufficiently before taking the pre boil gravity. In this case you would get an unnaturally high gravity if you took the sample from the bottom of the kettle, or a low gravity if you took it from the top.

-a.

**Yooper** · 10-16-2008, 12:55 PM

I'm going with the inaccurate hydrometer reading at high temperature. I found that even with the temperature correction tables, my readings were terribly inaccurate. I even added some water to my wort once based on the preboil gravity, and of course it was wrong and my OG was very low when finished.

I put a little pitcher of ice water on the counter, and stick my hydrometer jar in that and wait for it to cool to under 90 degrees before taking the reading. Try it- take a reading at 200 degrees and then cool the sample and take another. I bet they are totally different, even after temperature correction.