Gravity Measurement Anomalies?

• • SVA Brewer With Over 100 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • SVA Brewer With Over 100 Brews From United States of America
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Cheers todd;
I appreciate that it is still beer, it just makes me wonder why
Actually i think you are seeing the same thing as me; my last one was 13.1 Brix after boil then 11.2 after chill.

Plus, i have measured the same sample in the pipette five times, one after the other. Rinse refrac, clean cloth wipe etc. and found small differences that are probably negligible (say 13-13.4 Brix), but was surprised to see such a big difference between boil & chill.

• • SVA Brewer With Over 100 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

mally.

Your numbers are honest. Look for some of my posts that include the terms 'refractometers' and 'grapes'. Refractometers require a ridiculously small sample size and one speck of 'dirt' in a refractometer sample can throw the reading.

Until someone buys 3 refractometers and measures the wort at the same time and gets the same readings, then I really don't trust them. Why should I? I have five hydrometers here that rely on a much larger sample size and, even in the same sample, only two agree. I also have a refractometer.

Numbers Awareness - Stage 1

The numbers at our scale of brewing and with the equipment we have should not add up perfectly. If someone tells you they will/should, they are most likely at the first level of 'numbers awareness'. I'll sound totally arrogant in saying this but nearly all brewers who post on the internet are at that stage. In other words, they totally trust their expectations, usually given from software, and then make 'allowances' for how they must have measured wrong. That's perfectly natural. I certainly did it when I started out. It actually would have been arrogant for me not to.

Nearly all posters on the internet and even a lot of 'authorities' are at Stage 1. All commercial software is also at this thinking stage. It creates a viscous circle in the fact that most posters on the net are inexperienced brewers and so will naturally compensate in their posts so that they agree with whatever software they were using.

That's the way I started out and I don't feel bad about the first posts I did years ago that 'miraculously' agreed with the software that I was using at the time. The way existing software was then premised, and still is, means a few changes here and there will get you seeing the numbers you want to see and then you will report those and say, "Hit my numbers perfectly!!!".

But, the times, they are a changing...

Numbers Awareness - Stage 2 and onwards

Mally, you are way beyond Stage 1 which puts you in a very small percentage of the brewing community. From your posts here, I know you already have a good understanding of why we can't treat numbers (let alone commercial software) as 'gods'.

You don't get many posts as good as yours when it comes to numbers. YOur posting of honest numbers is a further indication that you are way beyond Stage 1. I wish everyone had the confidence to post the numbers they actually did get rather than those they expected. If so, there's heaps of questions we could answer, "on average"...

I don't think that numbers awareness can be classified in stages but another thing that would indicate to me someone is beyond stage 1 is the awareness that with the 'batch sizes' we home brewers do, and the equipment we have at our disposal, on average, estimates, are the best we can possibly hope for.

There's a lot more to write on this but I think the only important thing is to move out of Stage 1. Threads like this enable that. It's the second 'honest' numbers post I have seen here this evening. How good is that!!! Education is the big aim of BIABrewer so good on you mally .

PP

P.S. If you get time mally, shoot AcesHigh a PM and ask him to post here about 'stratification.' What he told me was very interesting but will take a few of us to check and get some 'averages'. Basically he noticed a massive discrepancy in his pre-boil gravity readings as well and I think he was using a hydro. If he doesn't know what you are talking about tell him to contact me.

...Had a lot more written above. Hope my distillation has made it a bit shorter without losing anything important for you.

• • SVA Brewer With Over 100 Brews From Australia
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

No Problem PP;
I would be interested to hear more, especially if it were to do with stratification, or where/why/how these anomalies occur.

My stage 1 numbers awareness is probably down to my university days. I actually used to be a clinical chemist in a past life, until i moved on to liquid handling calibration (also a past life).
So in essence i have an appreciation for why we need to take measurements, but more importantly not to trust them either. False positives/true negatives, not even mentioning precision & accuracy etc...

I still prefer my refrac though; to do the above measurements with my hydro would probably have left me with 200ml VIP

• • SVA Brewer With Over 100 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

mally wrote:I still prefer my refrac though; to do the above measurements with my hydro would probably have left me with 200ml VIP

Three easy measurements does not beat one good one. I am kicking you back to stage one .

Just joking....

There's actually so much to say here. I'm hot, tired, drinking too many light beers etc, etc so forgive me if I just have a stab at trying to put across these points...

I am constantly conflicted in how I offer advice on this forum. It is so dependent on who I think I am writing to*...

To some brewers, I want to say, "Take more measurements."

To others, I want to say, "Take less."

For a brewer at your level, I'd recommend the latter. Numbers are very unimportant, if you know what they actually mean.

Ramble, ramble, think, think, what I am trying to say is that numbers, the BIABacus, etc are a great set of trainer wheels when you are learning to ride a bike. The BIABaus has the best set by a long way.

But, any numbers are just trainer wheels.

If I was speaking to you directly, I would say, "Mally, stop taking so many measurements. You already know a single measurement can't be trusted so just focus on taking a few OG measurements."

I'd also ask, "How many hydrometers/refractomers/thermometers do you own?" Are they agreeing? If so, tell me how you managed that!"

You already know this stuff mally. Don't question it. The logic is as obvious as I know your brain sees.

Anyway, enough ranting and raving. One thing above you were concerned about was the amount of wort it consumes obtaining readings. Forums are great in some ways but they can make us lazy/stop us thinking for ourselves. They usually give crap answers but I hardly ever see one on this forum thank the brewing gods!

You actually have the experience and knowledge to structure and write an answer to that question you are asking here very well. Nearly all gravity readings do not involve a wort sacrifice.

...

I know BIABrewer.info is desperate for good writers. Most fail when asked to do a BIABrewer post for many, many reasons.The main reason is that they think it will take just a few hours.

Here's what I'm thinking now and I think you are capable of answering everyone of these questions yourself and communicating it to others...

1. What are the most important measurements I can take as a new brewer?

2. If I get ambitious and have time, what are the next most important measurements?

3. Let's say I've taken all these measurements, are they of any use?

4. I hate taking measurements as I think they cost me 'beer'. How can I take my measurements so that they don't cost me?

etc,...

There's lots of posts on this forum already that would answer those questions but many are impossible to find. That's the whole point of BIABrewer posts. They should be based on hours of research but someone has to be prepared to put in the diligence to distill those hours. In other words, someone has to slow down, read, think and then write.

BIABrewer posts always start with threads like this and usually require many, many posts before they are written. (Mind you, there's a few really bad 'BIABrewer' posts here atm from the very early days that still make me cringe. Best we could do at the time though - pretty desperate for authors).

Seriously though mally, in this thread, you are asking Q4 above. Why not use this thread to answer that question first? When you have an answer to that, maybe then move the thread onto Q1 etc?

It might be a bit of fun for you or too much to ask. I honestly don't know.

The only thing I do know for sure, is that if you do find a challenge a bit of fun/interesting, minds like yours will make BIABrewer. If not, I personally think a lot of work done behind the scenes here will...

Who knows?

BIABrewer is all about education. I can't remember but, I think, in Latin, education means something like, "to lead forth." I suspect that the founders of BIABrewer.info would have hoped for this originally but for now I think they'd be happy with "Iustus adepto aequum."


PP

• • SVA Brewer With Over 100 Brews From Australia
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Interesting post mally, I did wince though when you mentioned the refracto

I can't say I've noticed this with my brews but then again as long as I'm close I'm happy, I also seem to suffer from a habit of seeing what I want to see when taking a hydro reading.

My method:

1) After mash but pre-mashout; Take a hydro sample cool take reading add back to boil.
2) After mashout but pre-boil; DITTO
3) After boil but pre-chill; Not needed if you hit your volumes.
4) After chill but pre-ferment; Taken whilst transferring to FV. Drink or throw away.

So the above with a hydro cost you 100/200ml of wort.

I have recently bought a refracto more to scratch an itch if anything, I've yet to use it in anger but will see if I have the same reading quirk as you are getting when I do.



Yeasty

• • SVA Brewer With Over 50 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Wow PP, There is a lot of philosophising in there.

I didn't intend the post to make a case for or against either method of measurement. I have taken readings with both in the past (albeit a small size N sample) and I was happy that my hydro (i have 2 of them by the way) and my refracto (1 off) were giving similar results. To be sure though, next time i will use the hydro(s) & refracto and see if they are the same at this particular stage (if I remember to that is).

I was kind of hoping that this was an area/procedural stage that was known to give larger errors than normal. For example, Oh you need to give it a good mix after the boil, as there is a thermonuclear stratification of antidisestablishmentarianism Err.. that is a real word too!

Interesting post mally, I did wince though when you mentioned the refracto

Sorry Yeasty! It would be great to know if anybody else sees it though.

I was exaggerating about the hydro sample too! It should be a little more VIP than 200ml, but it isnt all about volume loss, there is also convenience.
One thing i was planning to do next was take all the samples i need to and do the measurements after the brew is complete.

Lastly, If i were brewing something i had done before, I wouldn't use either. I wouldn't care if i was out by a few points, or my IBU's weren't identical. However, in my last brew, which is a clone of Pendle Witch, I want as much info as possible because if it needs any tweaks, how would i know what to tweak?

• • SVA Brewer With Over 100 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • SVA Brewer With Over 100 Brews From United States of America
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

mally wrote:Wow PP, There is a lot of philosophising in there.

Probably drunken, delirious, babbling more like it . Every time we get a heat wave here in Perth I seem to get stuck on a job that requires pulling down brick walls . It's important to rehydrate so for every hour I work, I make sure I consume an hour's worth of light beer when I get home . That must equal a lot of water?

Out this evening so haven't got time to read through the above atm but I did see Aces's post above. One thing he didn't mention in that post which I'm pretty sure he told me was that he did give the wort a good stir before taking his samples. That's what pricked my ears up at the time but maybe I was drunk then as well?


PP

• • SVA Brewer With Over 100 Brews From Australia
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Even after stirring you saw this?
Has this happened occasionally or do you see it regularly?
Like i said originally, i have seen this 3 times so far, but it may be there all the time

• • SVA Brewer With Over 100 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • SVA Brewer With Over 100 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Interesting stuff on the proteins etc settling out GR and very nice job mally

mally wrote:i am happy with either method of measuring device, as long as the sample is clear.

One thing I should have mentioned before but didn't (because I never do it) is that to take an accurate reading, whether it be hydrometer or (and more so) refractometer, your sample should be filtered first. Think I was told to use the same filter paper as you would for coffee.

I think if you filtered samples though, you wouldn't have much time left to actually brew .

• • SVA Brewer With Over 100 Brews From Australia
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Rushed for time atm (lucky for you guys ) and would like to re-read GR's post above on salts and sugars in far more detail as I think there is something very relevant there. Here's the four main issues I think atm are important if you want to reduce anomolies...

1. Stratification - You must ensure that the entire wort is well agitated before taking a sample. (Applies to hydros and refractos).

2. Cooling - Whilst cooling the sample, you must avoid evaporation. (Particularly applies to refractos as the sample size is so small. For example, if you cooled a teaspoon of wort in the open air, any evaporation will increase the reading.)

3. Clarity - In the case of hydros this is not as critical but is still relevant. Particles will float your hydro. Also, be careful of most hydro tubes which are generally too narrow for accurate readings. In the case of refractos, the clarity is problem is much more pronounced. A wine maker uses a refracto to assess the sugar content of grapes in a vineyard. Grape juice is clear. The winemaker still takes many samples. We homebrewers should not expect the same accuracy for wort which is much more cloudy and particulate especially if we only take one sample.

4. Instrument Quality - One thing that should never be forgotten is instrument quality. Many hydrometers, thermometers, and probably refractometers, will read differently even after a basic calibration.

mally's experiment shows that under 'the perfect storm' of conditions, a refractometer reading can match a hydrometer reading. I think though, that the above four issues, especially when compounded, are the cause of a lot of problems we get in our real readings, where ideal conditions rarely occur.

Anyone got any filter paper?
PP

P.S. Nice pic GR on the filter thing. That's exactly what I was thinking of .

• • SVA Brewer With Over 100 Brews From Australia
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Really interesting points guys. I like the way it is heading with serious thought processes.
I don't mind being the lackey & continue to some sort of conclusion (although I don't think science ever has an "end")!

My initial experiment was as PP mentioned, to compare the 2 instruments under the best conditions possible, and this showed that they were. In fact i was surprised by the refractometer. I was expecting it to be fairly accurate but not precise, hence the 2 sigma confidence level (error bars), which are quite pointless on the graph now.

One problem i can see is what PP has experienced with other scientific procedures, is to define the best & next steps to take. If you just pick anything, you leave yourself open to "objections" further down the line.

Could the filter paper remove anything from the sucrose solutions? If so maybe it would be better to retest these solutions after filtering, to see if there is any difference?
You then get into the realms of, how accurate & precise the refractometer is with "other" sugars (wort is mainly maltose, as well as other "oses" which can allegedly skew readings by 2-6%).

It may end up just being "interesting" rather than scientific, but maybe that doesn't matter either

• • SVA Brewer With Over 100 Brews From Great Britain
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

• • SVA Brewer With Over 100 Brews From United States of America
  • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Thanks very much Joshua

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0

Sugars should be unaffected by filter paper. My wife just read Joshua’s post and said she filters through .22 micron PTFE filters at work (much finer than filter paper) and loses none of her simple sugars, and she "tests her recoveries". She’s a biochemist in a research station, working with fruit, but she likes not to be too involved in my beer, beyond drinking it

She didn’t know the size of the dextrins and what kind of filter would be required to filter them out. I think she said to google size of the dextrins in microns to see what kind of filter would filter them out.

• • Quote
• • • 0
    • 0
    • 0
    • 0
    • 0