SG and Temperature Compensation

[Peebee]

I've recently wandered on to this forum from over the Atlantic because I was made aware of me getting some flak on this forum. But the antagonist seems to have disappeared? Never mind, this is one of the subjects I was getting criticised for, so I'll give you all a chance to shout me down . The posts are as presented to a UK forum where I was sharpening up the ideas, so they're almost verbatim and may appear in in quick-fire time.

This is a "I hate hydrometers" post, so I start with a short introduction of why I hate hydrometers.


A few years ago, I had an accident. Knocked my eyes out of kilter, took five eye "squint" operations to make them approximately right but I still need prism glasses so as to correct the remaining double vision over most of my sight. I'm also ageing and need ever stronger reading glasses. On top of that the accident triggered something called "saccadic intrusions" ... I find it difficult to fixate my vision on something to see it clearly (and no glasses can fix that, it's in my head). Oh aye, and my hand tremors like a mad thing.

A fragile glass instrument covered in closely set parallel lines (a hydrometer) is a nightmare!

A refractometer can be used to gain a closely approximate reading of "SG" and are easier to read than hydrometers. Not ideal but an improvement (and you look cool peering through one in the light).

But it seems my "conditions" coincided with fairly accurate weighing scales becoming substantially cheaper! This fortunate coincidence not only meant I could continue brewing with an alternative to a "hydrometer", but also have a substantially better instrument for the job. I remembered them from my schooldays; a major achievement in its own right!

A "Pyknometer"! This one is a big one (100ml). I'd normally use 25ml bottles. These scales have been tricked into displaying the "SG" of the sample directly ... SG 1.0217 (move decimal point back two). But that's for later: For now, the total weight was 137.36g and the temperature just short of 20°C (19.8°C).

 

[Peebee]

Before diving in too deep, here's a demonstration

If you haven't a hydrometer or pyknometer even! You could try this (which might not be particularly accurate!). It's a demonstration of how simple pyknometers are using "Specific Gravity", and questions why we bother with hydrometers these days.

Have some water kept near the wort sample for an hour or two (so the temperature of the two liquids is about the same). Take a one litre PET bottle and fill it to the brim. Carefully replace the cap. Do not hold the bottle while doing this, have it free-standing on a flat surface. Weigh the bottle. Rinse out the bottle and repeat with the wort sample. The weighing scales can be ordinary kitchen scales capable of weighing grams, of tenths of grams would be better. The scales don't have to be too accurate, a gram or two out is fine, but they should be consistent! (Mine aren't, in the following example the wort sample weighed between 1,096grams and 1,101grams!). For sharper accuracy delete the weight of the empty bottle for both the sample weights (37g in my example).

Easy maths: WEIGHT OF WORT / WEIGHT OF WATER ... 1,059g / 1,027g = SG 1.039

Note no temperature, or even bottle volume! Those values would just cancel out in the maths.


Just for interest, let me see what the pyknometer makes of it (this is a classy 100ml pyknometer ... very flashy). The displayed spreadsheet is one of mine ... I'll make it available in a post a bit later:

Oooo! That were jammy! This method with PET bottles is a bit crude ... don't expect results quite as good usually (especially if using some naff kitchen scales like mine).

 

[sampling6391]

Sure hydrometers can be a pain sometimes. But they’re incredibly cheap and pretty reliable. The temp compensation has a convenient calculator too.

I too have eye problems and many times have trouble seeing the little lines on it. I will many times resort to taking a photo or two with my phone so I can zoom in and take my best guess. Recently I picked up a refractometer to help with starting gravity but it is completely useless for final gravity… Using pycnometer sounds interesting I like playing with glassware and scales. The only thing would be setup and calibration sounds like a lot more work?

 

[VikeMan]

Recently I picked up a refractometer to help with starting gravity but it is completely useless for final gravity…

Refractometers are not completely useless for final gravity, for reasonably standard beers. But the final "brix" reading does need to be run through a refractometer calculator (not just a "brix to SG" conversion calculator), along with the original "brix" reading.

 

[Peebee]

Specific Gravity (SG)? It has always puzzled me what it means. Google's no help. But I've been playing around with "SG" and "Relative Density" (which is in some way interlinked) for a while now, and it has suddenly clicked.

"Specific Gravity" means just that ... "this is the gravity", just like an English dictionary would describe. From Merriam-Webster's on-line dictionary:

specific [spɪˈsɪfɪk] adjective
1. clearly defined or identified. ...

The "Gravity" (or "Density", the two are used interchangeably in a brewing situation, before Isacc Newton and his apple, "gravity" just meant "weight"; from Latin gravitas) is the weight divided by volume. That figure dances about a bit due to changes in temperature and pressure, so, to make the value "specific" the figure references a substance held in the same conditions; the substance is usually water (or is it always water? Doesn't have to be but I've never come across anything else). By making such a pairing, "SG" becomes a ratio, which means no units ... it's just a number; and the SG of water is one (any number "referenced", or divided, by itself is one). And, most importantly: The value is automatically compensated for differences in temperature and pressure (within limits; freezing, boiling and outer space will provide some obstacles!).

Sounds ideal? But there were drawbacks: Weighing stuff to the necessary accuracy for brewing was tricky, hence "Brewers' Pounds" used the volume of "barrels" (36 imperial gallons!). Most brewers didn't bother. By the last quarter of the 18th C., brewers started to use new-fangled "Saccharometers" (hydrometers). They were cheap and easy to use. The problem with them is they didn't measure "density" directly (they do not deal with weights and fixed volumes, they are measuring "buoyancy" and "displacement") and therefore, lost the automatic temperature compensation. Still, thermometers were becoming common instruments and density readings could be manually compensated. It must have been advantageous for "SG" to continue to be used with these new instruments, but more likely some dozy tw&t 250 years ago thought it would be clever to put hydrometers in an "SG" strait-jacket.

And after two centuries hydrometers, and "SG", are still used for brewing. A rather minor hiccup recently is that "SI units" introduced "grams per milliliter" (g/ml) which looks identical to a "SG" (but it's not!) and water at its densest (4°C) is almost exactly one, like the SG of water is one, but really water is not quite 1.000g/ml and then only at that temperature (the SG of water is always exactly one whatever the temperature).

 

[Peebee]

Sure hydrometers can be a pain sometimes. But they’re incredibly cheap and pretty reliable. The temp compensation has a convenient calculator too.

I too have eye problems and many times have trouble seeing the little lines on it. I will many times resort to taking a photo or two with my phone so I can zoom in and take my best guess. Recently I picked up a refractometer to help with starting gravity but it is completely useless for final gravity… Using pycnometer sounds interesting I like playing with glassware and scales. The only thing would be setup and calibration sounds like a lot more work?

Sorry ... I said my posts might be "quick-fire" so I posted over you.

I think my last post probably answered your argument for hydrometers ... there is no need for temperature compensation with pyknometers. and "SG" is a temperature compensation!

The reason my spreadsheet (illustrated above) asks for temperature is taking temperature and using lookup tables for water densities is a lot easier than more messing about trying not to spill liquids.

 

[NSMikeD]

I broke another hydrometer. I noticed it when setting up my last brew. I have my refractometer and my TILT.

For the OP, after the boil, the TILT was placed in the fermentor linked to brewing software and provided numbers that were very easy to read on my phone. I would have only needed one refractometer reading for pre-boil gravity (If you track that) as the TiILT provides OG and FG.

This is not my screenshot but it is how it displays on my iphone.

hope this helps.

 

[McMullan]

The tools available to home brewers, including the cheap hydrometer, are sufficiently accurate to be of value. It's only beer. It's not a critical scientific experiment mankind is relying on or anything even remotely like that. But if anyone wishes to complicate their life and pretend it is, I can only recommend something like one of these:

https://www.agilent.com/en/product/gas-chromatography/gc-systems/8890-gc-system

 

[dmtaylor]

Measuring SG by weight is problematic for most homebrewers because:

• A fancy scale is expensive, and subject to user error, breezes, cleanliness issues, etc., and
• Most people are idiots when it comes to using fancy tools, i.e., no matter how good the instructions, they're not going to do it right, or it will not be consistent, or they'll fail to calibrate or zero it properly.

Plus, you're wasting now 100 mL per measurement instead of a few mL (at least for my cylinder), or a couple drops (with a refractometer). It's wasteful.

Nice concept. However, I'm a scientist (B.S. Chemical Engineer, and by title a Senior Chemistry Analyst), and you won't be seeing ME try anything like this. It's not going to work. I'm an idiot.

 

[Peebee]

@NSMikeD : Thanks. I'm already on that track! I'm a bit (a lot?) of a Density Geek:

Tilts (and TiltPRO) for monitoring fermentation (graphs by TiltPi), Pyknometers for OG and FG, and a refractometer for the "quick and dirty".

 

[Peebee]

The tools available to home brewers, including the cheap hydrometer, are sufficiently accurate to be of value. It's only beer. It's not a critical scientific experiment mankind is relying on or anything even remotely like that. But if anyone wishes to complicate their life and pretend it is, I can only recommend something like one of these:

https://www.agilent.com/en/product/gas-chromatography/gc-systems/8890-gc-system

I agree!

But I have said why I can't use hydrometers.

And beer or no, the subject makes for a facinating way to while away the time. I predict (which is a bit unlikely in this evolving world) hydrometers will get dropped in favour of a "new" method (probably a mobile phone app?) within a few decades and we'll all look back on those fragile lumpy glass things thinking "we did what ... ?".

 

[Peebee]

Measuring SG by weight is problematic for most homebrewers because:

• A fancy scale is expensive, and subject to user error, breezes, cleanliness issues, etc., and
• Most people are idiots when it comes to using fancy tools, i.e., no matter how good the instructions, they're not going to do it right, or it will not be consistent, or they'll fail to calibrate or zero it properly.

Plus, you're wasting now 100 mL per measurement instead of a few mL (at least for my cylinder), or a couple drops (with a refractometer). It's wasteful.

Nice concept. However, I'm a scientist (B.S. Chemical Engineer, and by title a Senior Chemistry Analyst), and you won't be seeing ME try anything like this. It's not going to work. I'm an idiot.

But the recent emergence like those scales I've pictured are changing the nature of things. They're cheap (<$50), electronic display damping, two decimal points of a gram ... not perfect, but more than adequate for this purpose. And in a few years ... well who knows?

I did say I use 25ml bottles ... cost about $3-5. That 100ml flask was gifted to me and would cost close to $100 ... using it terrifies me!

And finally: It does work. I've been using them for years (ask @McMullan, he knows that! And he did try to "disuade" me too ... he'll also tell you what an irritating, stubborn individual I can be ).

 

[Peebee]

[Continued]... A pyknometer does need a little maths to make it work. They are not setup for brewers to use off-the-shelf just yet. But I've created a couple of spreadsheets to do that for you (This thread was created to make those spreadsheets readily available). The "Lite" version is attached to this post ("Lite" in that it doesn't do all the fancy "stand-alone" stuff).

The bottle is weighed, and the temperature of the sample taken. These two values are plugged into the spreadsheet and out pops the answer ... SG 1.0381.

Hang on! I said temperature compensation is automatic! Well, it is, but thermometers are so cheap and easy to use, it's just quicker to take the temperature. The spreadsheet uses this to lookup the density of water at that temperature and use that as the S.G. reference. The temperature doesn't need to be crazy accurate; it only applies to the S.G. water reference, not the sample (that is already effectively "compensated").

Download the spreadsheet from the link below (it's the "Lite" version); it will open in Google "Sheets" which might not be what you want. The spreadsheet is created in Microsoft Excel, and only tested (briefly) in Google Sheets (Google "Sheets" does not respect cell protection setting so it is up to you to edit only the few Amber coloured boxes or else trash your copy of the spreadsheet).

The "Lite" version includes a "Density" option (currently SG), because you can do that with pyknometers and it can be handy at times. Not supported in "Sheets".

The spreadsheet has no passwords set. The spreadsheet should download from a link below (I've not tried doing this yet so may not work ... yet?). The download is zipped (because it has to be to upload).

 

[McMullan]

I predict (which is a bit unlikely in this evolving world) hydrometers will get dropped in favour of a "new" method (probably a mobile phone app?) within a few decades and we'll all look back on those fragile lumpy glass things thinking "we did what ... ?".

Maybe, but it’s superfluous to our needs and isn’t ever going to cost 5 bucks. The technology, resources, production, consumables, etc., won’t ever scale to the home brewer market or even Joe Public. It’s not a viable business model.

 

[BrewnWKopperKat]

°

 

[Peebee]

... I'm not in the "vision problems" category.

Neither am I! Or at least I don't aspire to be in that category.

I'm not a Loonie either. Because loonies never admit to being one.

 

[Peebee]

The "Lite" version is attached to this post ("Lite" in that it doesn't do all the fancy "stand-alone" stuff). ...

You don't actually need the spreadsheet. Or a "calibrated" pyknometer. Take an uncalibrated pyknometer, fill it with clean water (you still need the decent 2-deimal-place gram weighing scales if you want to get away with a 25ml bottle). Weigh it! Do the same for the wort (same bottle). Divide the weight for the wort by the weight of the water. Voila, the result is S.G. of the wort.

You do have to be confident the wort and water samples are the same temperature. The temperature doesn't matter nor its accuracy; the two readings just need to be the same (certainly within the same degree Celsius).

Easy? Just as Archimedes described it some 2,250 years (...ish) ago!



I've still to post a bit more ("read SG direct off the weighing scales"). It will need a 100ml bottle. And it's not like anything Archimedes described!

Note: I'm not attempting to get everyone using a pyknometer. Just trying to educate people what "Specific Gravity" is (including: It's got nothing to do with "hydrometers", except that "hydrometers" have "borrowed" the scale and, because hydrometers can't measure it easily, you'll need the necessary "temperature compensation" tables to go with it ... and a thermometer!).

 

[McMullan]

Pretty much all 'scales' outside stringently regulated (standardised) environments are actually 'borrowed'. It doesn't really matter that much relatively speaking in most cases. Apart from shoe sizes from different shoe brands. That's a royal PITA. Especially if you buy online. You can build a house perfectly using an inaccurate tape measure. Just make sure it's the only tape measure you use to build the house. It should all line up well enough. Same principle for a cheap hydrometer. It gives you a reasonable OG measurement, helps monitor fermentation progress and lets you know when fermentation is done, FG. Who cares if the beer's actual ABV is 5.2% or 5.4%? Run away from anyone who claims to be able to tell the difference. In your one-size-fits-all flip flops.

I have actually been using an EasyDens for the last couple years or so. Tested it thoroughly by diluting 75% ethanol in water and wort. Very precise dilutions using calibrated laboratory pipettes. I have full confidence in its measurements. Across a range of densities my >10-year-old cheap hydrometer covers, surprisingly comparable. In fact, were it not for the benefits (for me monitoring in detail) associated with only needing small (few ml) samples and the relative simplicity and automation, I think I would have wasted money. A cheap hydrometer can do almost as good.

 

[dmtaylor]

And I have proved that a properly used refractometer and conversion calculator (Brewer's Friend is the most accurate >1.014, Sean Terrill is most accurate <1.014, and if in doubt... lean towards BF) consistently reads within 0.000 to 0.002 max of a properly used hydrometer, and this includes FG where alcohol is present. Only a few drops and you're good to go, IF you know what you are doing (and that's a big IF). But I digress a little bit.

 

[Peebee]

I have actually been using an EasyDens for the last couple years or so.

Oh wow, an EasyDens. I bow to the superior technology. I have nothing left to argue with. So, a cheap hydrometer is almost as good ... doesn't mean much to me 'cos I canna read 'em. But an EasyDens ...

And I have proved that a properly used refractometer and conversion calculator...

... Eh ... sorry, what was that? Refract-o ... fingy? I fink you've just dropped out of the running.

 

[Peebee]

Right! Another day. And I better appreciate what I said "I'm not attempting to get everyone using a pyknometer" by getting the tap on the head with an EasyDens.

I'm NOT attempting to get everyone using a pyknometer. I'm attempting to get everyone appreciating what "Specific Gravity" means. So, I should put away my defensive attitude in favouring "Pyknometers". Afterall, I use Pyknometers and refractometers, and hydrometers (albeit electronic "Tilt" affairs). (I'd use an EasyDens, or any other oscillating U-tube device, if I could lay me'ands on one).

The spreadsheets I supply just make pyknometers more feasible as an option, as they don't come "ready-to-use. Yet they are the closest to what was originally intended analysing wort extracts (e.g. "How much sugar have I got that might turn into alcohol"?).

An idea of what all this "density" business is about should help end the common misconception that what a hydrometer says is the be-all-and-end-all of extract measuring when making beer.

My next post in this series should be interesting; it relies on using a pyknometer to emulate three (or more) hydrometers.


I've got someone to blame for all this rambling too: @Silver_Is_Money corrected me mixing up density (g/ml) with S.G. several years ago, setting me on this never-ending mission (unintentionally!).

 

[VikeMan]

I'm attempting to get everyone appreciating what "Specific Gravity" means.

I suspect most brewers could live long and happy lives without understanding the actual definition of SG. But an example where it can come in handy is in closed transfers to corny kegs, where you (of course) can't see the fill level. Knowing the mass per gallon of water and the SG of the beer makes it possible to stop filling at 5 gallons (or 5.2 gallons, if you want to live on the edge).

 

[beren]

I suspect most brewers could live long and happy lives without understanding the actual definition of SG. But an example where it can come in handy is in closed transfers to corny kegs, where you (of course) can't see the fill level. Knowing the mass per gallon of water and the SG of the beer makes it possible to stop filling at 5 gallons (or 5.2 gallons, if you want to live on the edge).

Pfft. wait for it to come out of the gas post.

For those of us who can't justify the expense of an easydens, you can get a very nice digital brix meter which only needs a few ml of liquid. It has limits, and there's some fancy math to get the FG with alcohol in it (you must know the OG and plug it into a calculator, with a wort correction factor)

https://milwaukeeinstruments.com/milwaukee-ma871-digital-brix-refractometer/ If you are patient you can get them used for $80-120-ish or new for $150

There's also near-unbreakable ones: Herculometer™ - Triple Scale Hydrometer

 

[McMullan]

I bow to the superior technology.

Is it superior? It’s mainly easier. But the measurements are pretty comparable to a cheap hydrometer. At least the one I have. In terms of cost, the hydrometer is far superior and I suspect home brewers spend considerably more on hydrometers than EasyDens units. Superfluous technology that can’t compete well in the home brewer market. A miniaturised GC unit is going to cost more than a new car. A limited box of consumables costing more than an EasyDens.

 

[Peebee]

... In terms of cost, the hydrometer is far superior and I suspect home brewers spend considerably more on hydrometers than EasyDens units. Superfluous technology that can’t compete well in the home brewer market. ...

Yeah, perhaps. But you shut me up mentioning it!

And I do keep trying to remind everyone: I can't use hydrometers. Trying to track down an alternative has led me to understand hydrometers are the source of a whole lot of my misunderstandings (and subsequent timewasting). Hydrometers and Temperature Compensation? "Specific Gravity"? Which is a temperature compensation (S.G. that is) ... but not for hydrometers! I never knew this stuff. And I don't think a lot of other people know it? Knowing it won't make better beer. But knowing it will stop a lot of time wasting running up blind alleys (time better spent on making better beer). That's what I really want to get across to a wider audience.


Well, not entirely that: That UK forum we once mutually used to contribute to is going through a "quiet patch". I'm trying to establish myself in an alternative.

 

[dmtaylor]

I really want to get across to a wider audience.

That UK forum we once mutually used to contribute to is going through a "quiet patch". I'm trying to establish myself in an alternative.

Maybe we should talk about topics that are more widely interesting.

 

[BrewnWKopperKat]

°

 

[Peebee]

Maybe we should talk about topics that are more widely interesting.

Humm ... but density needs to be more widely interesting!

For example: A quick search on this forum finds ...

... invention of the hydrometer, which when combined allowed porter brewers to realise that they got more bang for their buck using mostly pale malt ...

The big porter brewers already knew using pale malt could be more efficient. What the hydrometer bought was that understanding to the smaller brewers. Hydrometers were cheap!

And ... Why do we bother with "temperature compensation"? A lot of people don't (it's only recently I found I don't have to bother ... but I can't use hydrometers).


I did title this thread "S.G. and Temperature Compensation", not "I hate hydrometers".

 

[Peebee]

... My next post in this series should be interesting; it relies on using a pyknometer to emulate three (or more) hydrometers.

[continued] ... Using the "Full" version of my spreadsheet I got the details to create three "taring" weights configured for 13.5°C (blue), 20.0°C (green) and 26.5°C (red).

At this point I realise that this idea is a non-starter! Anyone who is happy enough to create these "Taring weights" will be quite happy using the pyknometer normally and wouldn't give a fig about reading the S.G. directly off the weighing scales! And I guess I'm one of them. Still, I've gone this far ...

The difference between the lightest (blue) weight and heaviest (red) weight is a massive ... 0.29 grams! Guess it's a good test of how okayish your weighing scales are. And your patience. Made from small glass vials, stainless steel ball-bearings, and coloured plastercine (top & bottom) to identify the weight, tune the weight, and stop the balls rattling about. You will need a partial lobotomy to attempt making them. I've had mine!

Now something to try it on ...

(Just to check the sample I'm going to use). Run it through the "Lite" spreadsheet, I've already taken the temperature:

S.G. is 1.040, the virtual water reference temperature was 16.6°C (61.9°F) ... [to be continued]


The "Full" version of the spreadsheet is below (should anyone want to tackle this lunacy). (Oops, too big! I'll put it in the next).

 

[Peebee]

Silly me. I hadn't "zipped" it:

 

[mac_1103]

density needs to be more widely interesting

Why, exactly? I'm a PhD microbiologist. I know what density is. I know what specific gravity is. I know a lot about yeast biochemistry and genetics. And I also know that there are tons of people out there who brew better beer than I do without knowing any of that.

Sorry, but it's not really clear what the agenda is here. It's not like the hydrometer hasn't been invented yet, and your solution is more difficult, more expensive, and adds basically nothing. It's great that it works well for your specific circumstances, but you must realize that those circumstances are not particularly common.

 

[Peebee]

[continued] ... Pick a "taring weight": With it at 16.6°C it's half-way 'tween the blue and green weights; I'll go for blue (13.5°C). This is the same as picking a 56.3°F configured hydrometer:

Hit the Tare button (display zeroes) and replace with the sample in the pyknometer:

Gaww, I'm a lucky so-so! That says S.G. is 1.040 (shift decimal point left two). One-tenth of a gravity point difference from a true pyknometer reading (recorded in my last post). But before I crow about it too much (it's the first time I've tried it properly) the result should have been about midway 'tween the simulated "blue" output and the simulated "green" output ('cos the actual temperature was between that configured for blue and green). Say 1.0404. Still, I'm not hunting for a two-tenths gravity point error.


Anyway. Back to earth. This is a barmy impractical trick which I've already given up on. You've got the calculations (spreadsheet), so do with it whatever you want! (If you can make money from it, please mention my name as the loony who created it).

 

[Broken Crow]

As long as a musket ball and a cannon-ball continue to drop to the earth from a tower at the same rate, I'll continue with my brain-damaged visual difficulties that sometimes require a magnifying glass, other times a picture taken on my phone and enlarged on a big screen, and all with the confirmation of a person who can stand to be around me, to use my hydrometer.

 

[Silver_Is_Money]

Silly me. I hadn't "zipped" it:

Nice work there PeeBee!

 

[Peebee]

I'll continue with my brain-damaged visual difficulties ...

It's not brain-damage ... it's "brain-injury". We don't use that nasty non-politically-correct phrase anymore. Or do they still on your side of the Atlantic?

 

[mac_1103]

He's talking about himself. He can be as politically incorrect as he pleases.

 

[Peebee]

He's talking about himself. He can be as politically incorrect as he pleases.

You didn't catch it did you. I bet @Broken Crow did!

 

[Peebee]

Why, exactly? I'm a PhD microbiologist. I know what density is. I know what specific gravity is. I know a lot about yeast biochemistry and genetics. And I also know that there are tons of people out there who brew better beer than I do without knowing any of that.

Sorry, but it's not really clear what the agenda is here. It's not like the hydrometer hasn't been invented yet, and your solution is more difficult, more expensive, and adds basically nothing. It's great that it works well for your specific circumstances, but you must realize that those circumstances are not particularly common.

Yes, you're right. I'm letting myself get off-track. I should be concentrating on what this stuff really means and not the way of measuring it. It's the mixing up of what it means that causes the confusions. Thanks (sometimes I need a kick up the backside to keep focused ... did you "get" that cryptic response targetted at you by-the-way ... the one concerning @Broken Crow?).

For example. This from a rather well-known Web-site. It's probably just badly written and putting across the wrong idea, the rest of the article is okay. But it also possibly comes from your academic world and they should have been more careful:

"S.G. for liquids is nearly always measured with respect to water at its densest (at 4°C or 39.2°F); ... ". What's water at its densest got to do with it? It would only make sense if the sample was at 4°C too. That's the sort of nonsense I'd like anyone to be able to identify and ignore. Along with "why do I need to worry about temperature and measuring density", "why do hydrometers measure values (S.G.) if it's quite inappropiate to a hydrometer", and the like.

Is that an agenda?



[For anyone else: There's no problem with hydrometers measuring in S.G. ... as long as you've got your temperature compensation tables with you 'cos S.G. isn't doing it for you any longer.]

 

[mac_1103]

That's the sort of nonsense I'd like anyone to be able to identify and ignore.

People have in fact been happily ignoring it pretty much forever.

 

[Peebee]

People have in fact been happily ignoring it pretty much forever.

I wish I had your faith.