Beer Forum

Today was my first partial mash and it was a blast! All went well though I still need to get my process down so I can get better organized. It took an hour and 40 minutes longer than extract.

Anyway, when I was done with the mash, I added some LME and my gravity was 1.034 ( I used a refractometer). Beersmith was expecting 1.033 so all is good! I boiled, hopped, cooled, transferred to a better bottle carboy and took my OG reading from what was left in the pot (.5 gallon). The OG read 1.043 and BeerSmith was estimating 1.038. I took a couple readings and all of them came back the same. What the heck? I've made this recipe many times with all extract and routinely hit 1.036 - 1.039.

I've used this refractometer for 10 -15 batches and have never had a freaky reading. I also routinely take my OG from what is left in the brew pot. Its usually one of the last things I do before I start cleaning.

As for the recipe, I mashed with 2.75 lbs maris otter, and 1 lb of specialty malts. I used 3lb pale LME.

Is taking the gravity reading from the bottom of the pot the problem? Or is something else going on here?

Thanks in advance!

Easy answers would be that either your mash was predicting a lower efficiency than what you got, or you boiled long enough that it was concentrated more.

+1 to boiling - also could have had a boil kettle with a large amount of surface area (increased boil off)

I did check the efficiency... not sure exactly how to calculate it with partial mash, but BeerSmith showed my actual mash efficiency a few % higher than what was estimated.

But the boiling is something I didn't think of... are you thinking I boiled off more than BeerSmith estimated so the final wort was more concentrated, thus giving me a significantly higher OG?

Mine have all been about 5 points higher than expected, albeit a small sample size. I figure that I'm just not that precise yet, despite having a very good grip on chemistry and related subjects (LOL, is that a fault here? I hope not, I have quite a few credits!).

Who cares about the exact numbers though if the beer comes out good, right? At this point I am happy because I'm drinking tasty beer that I brewed. There are various reasons why my OG has been higher, and I can't tell you what they are because I'm not measuring anything precisely enough to give a quantitative, scientifically accurate answer. My solution to this "problem" is to relax and have a home brew.

I do plan on getting Beersmith soon, btw. It's much easier than a slide-rule and a piece of paper...

alcaponejunior wrote:I do plan on getting Beersmith soon, btw. It's much easier than a slide-rule and a piece of paper...

Amen to that. My last brew I used Beersmith and nailed it. But more importantly (for me), it was a much more relaxed brew session. The biggest deal for me was getting the software set up to match my brewing system. Now that I'm dialing that in, I should be even more consistent. But 5 points up or down, I don't care.

Hoont wrote:But the boiling is something I didn't think of... are you thinking I boiled off more than BeerSmith estimated so the final wort was more concentrated, thus giving me a significantly higher OG?

Yup, that's my thought...