Anvil Foundry High Mash Efficiency - SG vs OG outcomes question

[Docod44]

Hi all, I brewed my second batch on my 6.5 Anvil Foundry today and copied Clawhammer's Candy Orange IPA recipe (Candy Orange IPA - Hazy Session). I am still dialing my Brewfather numbers in but today I found something strange with my SG and OG. Their recipe targets an OG of 1.046, I set my Brewfather recipe for a mash efficiency of 70% and an OG of 1.048 with a pre-boil gravity anticipated for 1.04. I mashed and sparged and collected a sample of wort to measure my pre-boil gravity and it was bang on 1.04. I remembered the temperature correction and measured the sample wort temp as 130 degrees F (it had cooled a bit in my graduated cylinder), making the pre-boil gravity 1.052 after correction. Obviously this is a huge overshot but I was also ecstatic that my actual mash efficiency was 89% and not 70%. I continued with the boil and did not add water to dilute my pre-boil gravity reading. I finished and moved on to the hopstand step, where in addition to hops some simple syrup is added. After cooling to 70 degrees F, I measured my OG and it was still at 1.052. What are some possible reasons my SG and OG readings would have been the same? Is the temperature correction really inaccurate? I've double-checked the calibration of my hydrometer and that wasn't the issue.

 

[doug293cz]

Tell us more about your process: did you recirculate, did you sparge, what was your strike volume, what was your grain bill, etc.?

Brew on

 

[myndflyte]

Could there have been stratification in the sample you pulled? So that the wort was actually more concentrated in your sample than throughout the whole volume of liquid?

 

[Docod44]

Tell us more about your process: did you recirculate, did you sparge, what was your strike volume, what was your grain bill, etc.?

Brew on

Hey thanks for the response, so I brewed a session IPA with 2-row (74.4%), carapils (9.3%), flaked oats (7%), flaked wheat (7%) and honey malt (2.3%). I mashed with 3 gal at 160 degrees for 60 minutes and used a recirc pump, raking the top third of my grain bed every 15 minutes or so. I sparged with 1 gal of 170 degree water (from a pot poured slowly over the grain basket). I pulled off my pre-boil gravity sample at this point and measured it when it had cooled to 130 degrees.

 

[Docod44]

Could there have been stratification in the sample you pulled? So that the wort was actually more concentrated in your sample than throughout the whole volume of liquid?

This could have been the case, per my other comment I pulled the pre-boil sample after I sparged by running my recirc pump into my graduated cylinder. The volume in the pump tubing had been sitting there for about 15 minutes before I pulled the sample off.

 

[doug293cz]

I agree with @myndflyte that stratification is likely the cause of the high pre-boil SG measurement. You need to make sure the first runnings wort and sparged wort are thoroughly homogenized before taking your pre-boil SG sample.

Brew on

 

[jdauria]

Were you using 120V or 240? Boil with lid on? If you did, then your evaporation rate would have gone down, but it really is impossible for pre-boil and post boil to be the same since the boil is condensing the wort, plus you added simple syrup. Did you stir the wort well after chilling before taking a sample?

 

[Docod44]

Were you using 120V or 240? Boil with lid on? If you did, then your evaporation rate would have gone down, but it really is impossible for pre-boil and post boil to be the same since the boil is condensing the wort, plus you added simple syrup. Did you stir the wort well after chilling before taking a sample?

120v system, lid was off for the boil. I agree this doesn't make sense especially since I lost 0.75 gal over the 1 hr boil, thus concentrating the wort. I stirred during the hopstand and when I added the simple syrup but not right before taking my sample 20 min later. Interestingly the FB anvil foundry group has a bunch of other people complaining of the exact same thing in one post (identical SG and OG).

 

[myndflyte]

It's got to be a stratification thing. There is just no possible way that the pre-boil and post-boil gravity can be the same, unless you have almost no boil-off.

 

[myndflyte]

Also based on your volume numbers, your pre-boil was probably around 1.041.

 

[Docod44]

I appreciate all of your help, I'll definitely stir really well next time before taking a pre-boil gravity. I'm just curious what calculation you used so that I can know what I missed or where I went wrong. I arrived at the pre-boil value of 1.052 because of the correction factor for a temp of 130°F based on a 60° calibrated hydrometer. Either my thermometer was wrong or it was a stratification issue like you said. Thanks again for the insight!

 

[doug293cz]

I appreciate all of your help, I'll definitely stir really well next time before taking a pre-boil gravity. I'm just curious what calculation you used so that I can know what I missed or where I went wrong. I arrived at the pre-boil value of 1.052 because of the correction factor for a temp of 130°F based on a 60° calibrated hydrometer. Either my thermometer was wrong or it was a stratification issue like you said. Thanks again for the insight!

Estimated pre-boil gravity can be calculated with the formula:

Pre-boil SG = 1 + (Post-boil SG - 1) * Post-boil Volume / Pre-boil Volume​

With your numbers that works out to:

1 + (1.052 - 1) * 2.8 / 3.55 = 1.041​

However, the above does not take into account the simple syrup you added. To correct for that we would need to know the volume and SG of the simple syrup, and whether or not your listed post-boil volume included the simple syrup.

Brew on

​

 

[myndflyte]

Ah yes. Forgot about the syrup

 

[Docod44]

Cheers, thank you both.

 

[jdauria]

Interestingly the FB anvil foundry group has a bunch of other people complaining of the exact same thing in one post (identical SG and OG).

Have had a few times where it's taking me 3-4 readings to get the right gravity using a refractometer. I also find that at 120V with the 1/2 gallon boil off that most of the time I am getting 5-6 point difference between pre-boil gravity and OG, but a couple times I have only gotten a 3 point difference...and with a refractometer using Brix, that could be 10.2 pre-boil vs 10.6 post boil...close enough on the scale for people to possibly misread it. So a small difference on a hydrometer could be misread also, or not adjusted for temp or the scale or it could be touching side of the sample tube giving misreadings. I serious think it's either human error and/or the narrow width of the Foundry causing an unusual stratification not seen in normal brew kettles.

 

[Huck604]

Could there have been stratification in the sample you pulled? So that the wort was actually more concentrated in your sample than throughout the whole volume of liquid?

+1 on stratification, often the opposite can happen if the wort is not stirred after sparging. The more dense wort from the mash can sit at the bottom and if the sample is taken from the top of the vessel it is likely diluted with low gravity sparge water/rinsings-->unexpected low gravity reading. Sounds like you managed to collect a sample from the bottom of the kettle and ended up with more mash "runoff" than a homogenous mixture of both sparge and mash runoff. Sounds like it worked out in the end regardless!