Bizarre gravity readings

So for my first AG brew, I went with the blonde ale out of brewing classic styles. I measured my preboil gravity at 1.035, which missed the 1.043 mark I was aiming for. I anticipated evaporation rates and boiled for an hour. I hit my final volume *perfectly* but this time the gravity reading was 1.060. Here's the recipe (converted to half batch):
4.6 lbs 2 row
3.34 (.21 lbs) crystal 10
11.59 g (.41 oz) ekg
mash 152*F for 60

Pretty simple. It's not evaporation since I hit my preboil and final volumes dead-on. I have no idea what could have happened. I'm about to add boiling water until I'm on with my gravity and then pitch the yeast when it's ready. Any other suggestions regarding this mystery???

What was the temperature of the wort you took the gravity readings from? Did you adjust for the temp?

No I didn't and I was wondering if that had anything to do with it. When I took the preboil gravity (low at 1.035) it was probably around 130*F. For the starting gravity (high at 1.060) it was around it was 67*F. I lost my paper that came with the hydrometer to adjust for temperature, so actually my preboil gravity might have been closer than I initially thought. Either way, it seems bizarre that my starting gravity ended so much higher. Please let me know if you have any more ideas...I have two weeks off and I want to brew like crazy and I don't want them all to have the same problems.

*I didn't mashout (if that makes a difference) and so it sat for a little while it was reaching boiling (about 25 min past when I took the measurement.)

Most hydrometers are calibrated for testing at 60 deg F. The usual correction is to add .001 to your reading for every 10 degrees above 60 deg F that the sample is at, conversely you would subtract .001 for every 10 degrees below 60 deg F. Their are several converters on line, and brewing software such as Beer SMith should have the calculations as well.

So if you sampled at 130 deg F, you would have to add .007 to your reading which would have put you at about 1.042.

The reading you took after the boil at 67 deg F is about correct, you can add .001 to it if you like as it was 7 degrees above 60. The reason it was so much higher is you are measuring sugars as a percentage of your liquid volume, and you probably boiled off 1 to 1-1/2 gallons during your boil, so the sugars would now be a larger percentage of your liquid volume as you have less liquid after the boil.

You do not say what your target gravity was after boil. If your pre-boil target is 1.043, and you are supposed to boil for an hour, and the recipe calls for no top off, then you should have a higher target gravity post boil.

take another reading.
as for the 1.035, corrected for temp at 130 it is 1.048. if it was 140 it would be 1.051.
I don't see how it is possible to increase gravity without adding solids into the water. check your hydrometer and make sure it is working properly. Is this a 2.5 gallon batch or 3?
if it is 2.5 gallons and you had 84% efficiency it would be 1.060.
3 gal would be 1.060 at 100% efficiency.
I wouldn't add water, that will screw with the ibu. just ferment it and see where it ends and then work back from the final gravity with the attenuation of the yeast to see where it was to begin with.
bottle it and age it for some time if it is strong.

robertjohnson said:

Either way, it seems bizarre that my starting gravity ended so much higher.

Click to expand...

You HAVE to correct for temp! It makes all the difference. Your pre-boil gravity being measured at approximately 130F is way off from the actual. You thought you were too dilute, but you were actually too concentrated and needed to sparge more! 1.035 measured at 130F is really 1.048!!! You can add some water to this batch, but I'd just leave it alone and learn from it.

Next batch - be sure to correct for temp. Keep using pre-boil gravities, just keep sparging until your wort in the boil kettle is at the correct gravity (adjusted for temp of course).

There has to be a hydrometer correction tool online somewhere. I use promash, so I have at the ready. I use it several times during my brewday to correct hydro readings.

Alright, thanks for the help. Adjusting for temperature it seems like I actually got better than the 73% brewhouse efficiency assumed in brewing classic styles...not bad for a first attempt. Looks like I need to calculate my efficiency to adjust for my next recipe. As for any missing information: The target gravity after the boil was 1.050, I got 1.060. The preboil gravity was 1.043, I got 1.048. THANKS FOR THE HELP!

To Zen Brew: I hit my final volume spot on (2.5 gallons from 2.92) and anticipated my preboil gravity being lower than my target gravity from concentration. What I didn't understand was why my preboil was almost .01 points lower and my postboil was almost .01 points higher. It seems like adjusting for temperature puts me consistently above the gravities listed in the recipe, which I would think means I have better efficiency than anticipated. Just thought I'd clear up any confusion. Sometimes I don't explain myself very well. Thanks for the help.

I've also read that the further you get form the calibration temp, the more off it becomes. So it might have been even higher than 1.042 from the mash tun. You basically need a refractometer, or a way to rapidly chill that wort sample to 70-80 degrees F to get a good OG from the tun.

+1 on a refractometer. If you keep an eye out for one they can often be had in or about the $30 range. I got one on the "bay" for a good price.
Make sure if you pick one up it is rated for beer/wine brewing use, usually indicated by a brix scale. Common brix scales for brewing are 0-30 or 0-40. Automatic temp compensation (ATC) is a useful feature also.
There are refractometers made for other uses that are harder to correct for brewing so make sure to check.

Thanks for all the advice. This has definitely been helpful. I'd love to get a refractometer, but I need to cap spending right now.

And in case anyone was still interested...I'm estimating the temperature was more like 145 when I took that reading. I did some calculations and cross-referenced it with my target gravity measurement since I was sure about the temperature on this one. This gave me a preboil gravity of 1.052 and a consistent brewhouse efficiency of 88%, which seems too good to be true. But my math inspires me to brew again tomorrow, and makes me feel justified in f'ing around with my corona mill for so long.

Beer Math Link

This is a handy little applet for a bunch of different beer calculations; I use it for adjusting gravity readings.

Oops! It appears that I'm not allowed to post a certain compound word, but a google search for "Beer math calculator" should turn up the same link.