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Messages - a10t2

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General Homebrew Discussion / Re: Brix only
« on: May 18, 2017, 10:59:50 AM »
Refractometers don't measure gravity, they measure refractive index. Your starting and ending "Brix" readings aren't even measuring the same thing.

I really hope I'm wrong and you can find a numerical solution, but pretending beer is sucrose and ethanol isn't going to help.

General Homebrew Discussion / Re: Brix only
« on: May 18, 2017, 10:39:43 AM »
I'd encourage you to read my writings on the subject. Validation used 68 data points from eight brewers.

General Homebrew Discussion / Re: Brix only
« on: May 18, 2017, 10:12:55 AM »
I used your calculator and got %ABV for the same numbers as: 6,5  6,2  6,0  5,7  5,6

That is quit some difference. And it is systematically decreasing for lower start brix, but with same delta brix.

As would be expected; most of those calculators haven't been updated since 2010, and the old correlation consistently under-estimates final gravities. The BrewersFriend calculator uses my formula; you're probably getting higher ABVs due to not applying a wort correction factor.

I don't have much trouble with the goes-in goes-out identification but on the kegs I have that have different colored o-rings I always forget which is which, so that's useless for me.

Black for liquid, grey for gas, so that they match my plastic disconnects.

General Homebrew Discussion / Re: I can make some delicious wort
« on: May 17, 2017, 03:05:27 PM »
OTOH, I've used nothing but buckets for the last 12-14 years and have never had off flavors from it.

I have four buckets now but one of them is the original from the homebrew kit I got in 2004. I've been meaning to replace that one though; the plastic piece on the handle fell off and the metal really digs into my hand.

General Homebrew Discussion / Re: Brix only
« on: May 17, 2017, 02:46:20 PM »
OK, so this is a combinatorial approach based on refractive indices? Using sucrose and ethanol seems to make the constants work out. Beer is significantly more complex, which I think is why it deviates so much from that approach. FWIW, trying to figure out better reference solutions of sugars, starches, and alcohols was going to be my next tack, but that leads down an experimental rabbit hole because refractive indices aren't additive.

I forgot to ask you if the Brix values you used in the test where readings or calculated ( from gravity measurements)?

Those are the uncorrected refractometer readings. If you're interested, my looking into refractometers starts here:

General Homebrew Discussion / Re: Brix only
« on: May 17, 2017, 11:43:53 AM »
My thoughts:

2. Why? What is the theoretical basis?

4. Again, why? Why is the ABV always equal to 0.88(Bo - Bf), regardless of alcohol content? This approach assumes no dependence of the refractive index on alcohol in the sample.

6. Why is the correction factor always 5%? Doesn't this vary with wort composition?

For my last five batches, the formula in (4) gives ABVs of 4.1%, 7.6%, 6.9%, 8.1%, and 5.2%, compared to "actual" (∆Plato * 0.525) hydrometer ABVs of 3.5%, 7.0%, 6.0%, 7.3%, and 4.6%. The trend of over-estimating ABV seems consistent, which is in turn consistent with not accounting for alcohol in solution when taking refractometer readings. Why do you think this approach is immune to that problem?

Edit: Not to toot my own horn excessively, but my calculator gives ABVs of 3.5%, 7.1%, 6.0%, 7.2%, and 4.6% for those same five batches.

I use a cooler, but I have to stir for, literally, 2-3 minutes to get a uniform mash temperature ±0.5°C. Usually I just stir less and settle for ±1°C. What kind of variations are you seeing?

General Homebrew Discussion / Re: I can make some delicious wort
« on: May 13, 2017, 04:43:12 PM »
Worsening over time, both within a batch and batch-to-batch, makes me suspect contamination first.

Do you use a heat exchanger?

I resolved to just live with it since I'm already 2.5 hr behind and letting the unboiled wort sit around overnight didn't appeal... minor miracle, the outside of the kettle (the pinhole is right at the bottom) got hot enough to caramelize and seal the hole.

Time for that new kettle I've been talking myself out of for a couple years.

Equipment and Software / Patching a pinhole in a stainless kettle
« on: May 13, 2017, 03:08:24 PM »
Anyone have suggestions for a temporary fix? Asking for a friend, definitely not because I'm standing here with a tun full of wort and a leaky kettle.

General Homebrew Discussion / Re: I can make some delicious wort
« on: May 12, 2017, 11:29:49 AM »
I am still pondering the cause. I think I will soak my fermenters and transfer hose in a strong bleach solution just in case. I use starsan normally but maybe using a different sanitizer once will help.

If you're using StarSan as your primary, it's definitely a good idea to switch it up every few batches. DBSA is broad-spectrum against bacteria but there are Brett strains that can tolerate ~2 pH for ~30 min, for example. I'd suggest an iodophor instead of bleach though, just because of the odor issue.

General Homebrew Discussion / Re: Hydrometer Temperature Accuracy
« on: May 12, 2017, 11:13:53 AM »
I'm confused.  The gentleman I quoted a10t2, said it could have affected the measurement.  You yourself said the problem was maybe the mixing.  Doesn't getting a correct reading from a refractometer depend on a homogeneous sample?

Two different things being discussed in this thread:
  • Refractometer vs. hydrometer: For hot-side readings, the small volume of a refractometer sample makes it easier to obtain readings quickly. The flip side is that the small sample is more susceptible to evaporation effects, so it should be drawn using a pipette/syringe/etc.
  • Full boil vs. partial boil: After mixing wort and water, there's no practical way to obtain a homogenous sample. Regardless of what you're using the take the readings, the way to get an accurate OG is to measure the wort gravity and then calculate the effect of dilution.

I use a hydrometer not a refractometer. I am guessing everybody that was referring to mixing was talking about samples for a refractometer and not a hydrometer sample which is much larger and presumably of much more uniform gravity.  I did not initially understand.

No, trying to homogenize wort and water is independent of measurement technique. It would take, quite literally, several hours of stirring to obtain a homogenous sample with either instrument.

All Grain Brewing / Re: IPA hopping technique survey/poll?
« on: May 10, 2017, 11:22:41 PM »
If flameout and whirlpool/hopstand hops are different answers, could you clarify? I'm not sure which I would be doing.

Kegging and Bottling / Re: Score at LHBS!
« on: May 10, 2017, 11:05:56 PM »
A 20-bottle case? Are they ancient, or just weird? ;)
German branding on the side. 20 is Pretty standard there.
Better eyes than me, Jeff!

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