Cheers mally. Kai's tables will work fine (assuming your wort correction factor is 1.04 and is correct for whatever wort you are testing* and that your sample is a good one and the way that you take your sample is sound and temperature-corrected) for gravities containing no alcohol i.e. OG's and before.

Did you get all that?

For gravities containing alcohol (fermenting and final gravities), I'm not even going to go there, because there is nothing around that is better than being a poor estimate as far as I can see. I think the first para above shows that even a non-alcoholic sample poses many problems.

*Went to shops twice today and both times forgot to buy food colouring (see prior post)!!!

mally wrote:What is "spruiks" BTW? I like the sound of that!
You should get active on the HBT BIAB thread. That would keep you entertained for years!

I'm guessing the latter might cause more sleepless nights . As for spruiking...

One example of a spruiker is someone standing outside a shop, usually with a megaphone, shouting loudly about the usually dubious merits of the goods within. I think spruiking is best explained though, in this short video.

I believe in England there are known "Touts".

In America they are known as "Solicitors", like the People that sell items on American Cable Channels, Late At night.

Like NuWave cooking, the "Best Pressure Cooker Ever" and "Try Total Gym".

PistolPatch wrote: I know a drunken mod accidentally deleted a thread a few days ago , but he saved all the posts and it wasn't a major drama; I don't care and I had written in that thread. Last time before that I can remember was ages ago and would have, without doubt, been because someone was aggressive (maybe me? ).]

Breakfast Stout isn't just for breakfast any more. That mod is now perhaps legendary.

mally wrote: Sean Terrill will give you a more inaccurate S.G. but you will be able to get an F.G.

The refractometer Brix 15.4 sample converts to 16.01654 Plato and 16.01654 Plato = 1.0655 OG

Using the ST Excel calculator or his online calc, what would be the FG of a refractometer Brix 8.6 ?


I too appreciate your time spent on that Pat.


P.S. don't forget the food colouring.

Are you able to take measurements Richard?

You had O.G. 15.4Bx which we will have to assume is around 1.066 (not 1.060).
F.G. of 8.6Bx which I would say is around 1.016.

Can you check that with a hydro?

Even with all this info, you would still need to check your WRI as we are presuming the O.G. is correct at 1.040 values.
Even after that, we are not scientific labs. It's all horseshoes & hand grenades!

[Wrote this while mally was writing the above. Apologies if there is any repetition.]

Mad_Scientist wrote:Using the ST Excel calculator or his online calc, what would be the FG of a refractometer Brix 8.6 ?

With your numbers it says 1.016/4 BUT, BUT, BUT...

PistolPatch wrote:For gravities containing alcohol (fermenting and final gravities), I'm not even going to go there...

Jeez Richard, you seem to be hanging on like grim death to that bloody refracto . Let me know if anything I've written doesn't make sense above or here...

1. Re-read my last posts here on the problems of even getting a correct wort correction factor.
2. Last post showed that the calculator gives incorrect OG so why would we place further trust in it? (Read the posts at the bottom of the calculator page where several people are getting negative final gravities - it is simply not accurate.)
3. The formula, which we have established several times now, is not accurate, is based on only ten beers, which, on an experiment like this, is nowhere near enough. (Also read the comments at the bottom of this page, especially Jim Gossett's.)

But most of all...

Even if there was a decent formula, using a refractometer to determine final gravity is, physically impractical compared to what I would recommend you do (below). Opening a fermenter tap over and over and collecting a few drops of probably dirty beer, is not going to give you a great refracto reading, and, if you are a safe brewer, you'll be spraying a bit of no-rinse up the tap after each sample. So, it's messy and unreliable even before the dodgy guestimate formulas.

A practical reliable and accurate method.

After you have pitched your yeast and agitated your wort, take a hydrometer sample (making sure you are using a proper hydrometer tube, not the narrow crap one that comes with hydros), take your OG reading, leave the hydro in the sample, place it next to the fermentor, and cover the lot with a large clear cover (there are simpler ways to cover it but I'm out of time.) So, it'll look like the pic below...You'll now be able to watch fermentation occurr in the hydro jar. When you think it's over, you can give the hydro a spin a few days in a row to see if it moves. The jar and hydro will be messy though, just like your fermentor, so once the hydro has stopped moving, take it out, clean it and dry it and then put it back in to get your correct FG.

Are we there yet?
Pat

P.S. I forgot the bloody food colouring but, I did all the reading above on a subject I am not interested in, as I already know it is a dodgy area as I have studied it before. So, why do I have to be the one to buy the food colouring? I did the urine test which no one else did and that is your first step . I honestly don't have time to spend on this subject anymore so, if you're interested, do the tests and let us know how you go!!!

I promise that I'm not drinking, atm. It was unfair to ask mally that question after ST calc was found crap. Bloody ST. My apologies kind sir.

Once again 'top stuff' Pat.

Nice read that Jim Gossett wrote.

All information has sunk in. DO NOT USE ANY refracto calculators.

Lessons Learned
If using a refracto to find your SG on un-fermented wort, proper temp, good sample, etc., multiply refracto brix # by (correction factor) to 'find' Plato, then approximate SG using Kai's table.

To find your personal correction factor get hydro °P divided by refracto brix #.

To find your FG, just use a hydro or finishing hydro.

FG number based on 'short range' hydro
Hydro measured 4.33 °P. 4.33 times 4 = 17.32, that's a 1.017/3 FG. This affirms a good apparent attenuation.

Thanks again for all the good work you do Pat. I hope that your good work gets discovered on the interweb.

For beginners, there are Duel Scale Brix and Specific Gravity Refractometers. You may need to be "Made of Money" see http://www.amazon.com/Beer-Wort-Wine-Re" onclick="window.open(this.href);return false; ... B006GG0TDK

joshua - typo or not, the refractometer scales do duel. What is it that one is trying to measure and what is the best way (tool) to measure it? At mash-out and at VIF when I want to measure the concentration of fermentable and non-fermentable sugars, the hydrometer gives me the density of the solutions. At the end of fermentation, I'd like to know those same things plus the alcohol content. The hydrometer only gives me the density of the solution. The readings and their differences are useful because they correlate to experimental experience where (I would like to think) the proper measurements were made with different equipment.
The refractometer measures the index of refraction of the solution. I think the error bars are bigger for the refractometer when brewing different beers and using different yeasts and later converting to OG and FG.
A PP style analogy would be like driving a manual transmission automobile and using the tach instead of the speedometer to determine the speed of the car. But Officer, I was only going 2800 rpms. They are related, but not measuring the same thing - and as the conditions change, so does the relationship. One can get a good feel for speed from the tach, but it is not distance/time that is measured.
True, the refractometer uses less sample each time and gives a number quickly.. You can choose your favorite method of measurement, but the numbers you get may not reflect what you would like them to represent. I am more comfortable with SpG for OG and FG, where they tell the density of the solution, then use those for an approximate ABV.

Mad_Scientist wrote:Lessons Learned
If using a refracto to find your SG on un-fermented wort, proper temp, good sample, etc., multiply refracto brix # by (correction factor) to 'find' Plato, then approximate SG using Kai's table.

To find your personal correction factor get hydro °P divided by refracto brix #.After doing about thirty tests.

To find your FG, just use a hydro or finishing hydro.

A great summing up MS. (Added one bit in red above .

I thought that would be the end of the thread, a thread we should rename to, "The longest, most circular thread ever on BIABrewer.info" . But, but, but, it still goes on .

joshua wrote:For beginners, there are Duel Scale Brix and Specific Gravity Refractometers.

Analogies are the go SP .

A refracto that has Brix and/or Plato plus a Specific Gravity scale will have been made to take samples of pure sugar solutions. The SG scale will not give you the specific gravity of your sweet liquor, wort or still beer.

This thread started out with a very simple and good question. The answer is also very simple - see what I've quoted MS on above.

...

What I don't like about this thread is the continued argument based on hopes or beliefs rather than finding facts/evidence. I don't think, for a second, that any of the key members here are lazy. I do think, though, we really lost the plot on this thread. To put it very coarsely, anyone seriously interested in this thread should have pissed in their hydrometer jar by now. It's not hard and only takes a minute.

I did it the morning after I suggested it in another thread. I wrote the readings down on a bit of paper and had them sitting on my desk expecting someone to ask for the results. From memory, I challenged others to do the same. No one did and no one asked for my results. The paper I scrawled the results on is probably still here somewhere (I remember 1.015 and a considerable variance between hydro and refracto).

So, we are all probably getting a bit lazy which is not the best example to set for newer brewers.

One Request

I'm busy tomorrow morning. Regardless, I'll try to remember to do the urine test. If not tomoz, I'll do it the following day (morning is best). I'll also post my results here.

All I ask is that you do the same before posting to this thread again.

Stop being lazy!
PP

Who wrote the grumpy post above?

Hold on! . Come on fellow brewers, I was just trying to take the piss out of you. (Oh no, this thread is not only bringing the coarseness out of me but also the poorest puns )

Anyway, you lazy buggers, here's my results...

[center]Refractometer versus Hydrometer Tests[/center]

I tested the following samples; plain tap water, urine, urine/sugar/coffee mix, sugar/coffee mix and a sugar/water mix. Here's a pic of one of the tests. Before downloading the spreadsheet, what test do you think it is? (You'll be wrong ) The Results

You can download this spreadsheet for the results.The spreadsheet makes the results look a lot easier than they were to take. I had the usual sample problems, for example taking two samples, after mixing, from the same large sample, and getting two different results, as well as "creep" (explained below).

One thing I learned that I hadn't really put much thought into before due to the countless problems I've had in the past measuring actual wort, was the temperature aspect of refractos. Most of us know that if we take a hydrometer sample, we need to adjust the reading back to the temp the hydrometer is calibrated at (usually 15 C or 20 C). But, if you are taking a refractomer sample of say hot wort (which you shouldn't do), what temperature should you make the adjustment from? It might seem obvious to me now, but it wasn't before - use the temperature of your refractometer i.e. whatever the ambient temperature is. For example, it's relatively hot here so ambient temperature and therefore the temp of the body of my refracto ranged from 29 C to 26 C throughout the duration of this test.

Btw, my hydrometers and refracto asssume a temperature of 20 C. I have several hydrometers but the two I used are my most trusted ones. Note, however, that they still have about a 1 point discrepancy between the two.

On the tests marked *** and ****, to mimic darker worts, I used instant coffee (forgot to buy food colouring again!). The latter of these was much darker than the first.


Main Observations

1. As mentioned above, problems getting agreement from two identical samples on some of the tests (Tests * and *** for example).

2. "Creep" on one of the two tests where I actually looked for creep. By creep, I mean reading the refractometer sample, letting it sit for ten minutes, and then reading it again only to find the measurement has risen. Creep occurred on Test ** but no creep from Test ****/*****. (Also see next point).

3. Basically impossible to get a reading on the darkest coffee test which had the colour of a Schwartzbier. There was basically just a gradual blur from white to blue looking through the refractometer. In my results, I said 11.2 to 14.2 but I changed the 11.2 from 10.2, thinking I must have read the refracto wrong.

4. Very clear view through the refracto on the sugar/water mix. In fact, that is the pic above. I used raw, not white, sugar - about 8 heaped teaspoons in a coffee mug. Urine was darker.

Before Readiing the Conclusions

1. The above tests were done on solutions of far less complexity than wort.
2. The above tests were done on ambient to warm solutions. A far higher degree of error would result if the above solutions were heated to mash or boiling temps.
3. This is one set of tests, from one person.
4. Only one refractometer and two hydrometers were used in the tests (on some tests only one hydrometer).

[center]Conclusions[/center]

The first conclusion is that these tests are as simple as you will ever get. The above tests are much easier than measuring ambient wort, let alone hot wort or beer.

As mentioned above, the refractomer readings, except for plain water and the sugar/water mix, were difficult to arrive at. (Two samples reading differently even though taken from the same, well-mixed larger sample and "creep" are two examples.)

Even given the limited number of tests done above, it wouldn't be unreasonable to hypothesise that the darker the sample, the more unreliable the refractometer reading, assuming you can even get a reading.

The only tests where the refractometer and one of the hydrometers came close were on plain water where the refracto and Hydrometer 1 matched, and on the second urine test where Hydrometer 2 came very close to the refractometer.

...

When I first started all-graining, I could never understand why a mash brewer would use a "traditional" paddle. It was unheard of at the time, but on my first mash, I bought the paint stirrer/potato masher that is becoming more widespread each year (I'm actually very proud of that ). Similiarly, whilst I'm pretty sure I do know where refractometers started in beer brewing (an Australian retailer), once I got past my excitement at the purchase and started really testing my refractometer out, I really questioned if they have any real place in brewing. Every time I examine the issue in detail, and I've done it many times now, the more certain I am that it is an unnecessary purchase, a purchase that can even often obstruct learning.

On top of all that, a hydrometer on a brew day and during fermentation, can far more easily and accurately do anything a refractometer can, for the same amount of wort.

I've said before, that refractometers are great if you are making wine; you go into the field, squeeze grape juice (always light coloured) onto your refractometer, take a reading and then walk to another part of the vineyyard and take another grape. The winemaker repeats the process many times, and, the average of those samples, gives him/her a very good idea of the sugar content of the entire vineyard.

But, for beer brewing??? I'm sorry but I really don't think so.

PP

Hooray!
PP nailed it, as usual.
I have used some antiquated instruments over many years of lab experience. The kilo lab once had a beautiful refractometer about the size of a typical high school microscope. The ONLY times it was useful were when checking the distillate from a tank to quickly see if the result perfectly matched the index of refraction of the pure solvent and for supportive evidence that a liquid was what it was supposed to be in its pure unadulterated state. Refractometer measurements of mixtures were basically useless results unless it was a yes-or-no test. Even well documented azeotropes were not especially trusted results, only a pure single solvent match-up was valid.
You can make the one you already own a useful tool for your own select purposes, but it can mislead others who are brewing at home.
Thanks, PP.

Thank you SP for posting that .

It's always a bit uncomfortable challenging something like this refracto area, sometimes you think, "Is it only me that gets these results?" . Your post definitely makes me feel more at ease .

Even though I gave up on the refracto ages ago, it was still interesting for me doing the tests. It would be interesting to hear if those who do use a refracto for some parts of their brewing, have more difficulty with darker worts than light ones.