Read my hydrometer - PLZ

[Pkrd]

I do hope everyone understands that however you read a hydrometer, bottom or top of the meniscus, or anywhere else, you must read exactly the same way when calibrating, while noting any deviation from the expected "null" point. Then apply that correction to every reading from there on with that same amount.

Yes it's absolutely critical to replicate the same conditions when calibrating, taking OG and FG..
That includes careful preparation on bottling/kegging day by having the same three brew day beers you usually chug during the boil while forgetting to add the hops.

 

[Pkrd]

It actually boggles my mind (a little) that there are some hydrometers calibrated/coming with instructions to read the top. I'm pretty sure that the height of the meniscus varies a little with wort properties. If so, that would mean those hydrometers are intended to measure an approximation. Maybe it's not big enough to make much difference. But it offends my delicate scientific sensibilities. I think I need a safe space.

Standard for opaque liquids, so no big thick stouts for you.

 

[VikeMan]

Standard for opaque liquids, so no big thick stouts for you.

Heh. My standard "pastry" stout base beer is 1.120 -> 1.050.

 

[IslandLizard]

I guess the main thing I’m taking from hydro readings is that’s it is specific to how that specific hydro was designed to be used/read.

Sorry, but that's not the main thing at all.
It's actually the very opposite:
The essence is, you may read a hydrometer anyway you want, but do it consistently, and the same way as you calibrate it!

For example, you may prefer reading your samples at the top of the meniscus and at 68F.
For that, you need to calibrate at the same temp (68F) and read the same way (the top of the meniscus) and note the deviation from the baseline (1.000 SG / 0% Brix). Then apply that same deviation to your samples, read at the top of the meniscus and at 68F.

 

[brewswithshoes]

Sorry, but that's not the main thing at all.
It's actually the very opposite:
The essence is, you may read a hydrometer anyway you want, but do it consistently, and the same way as you calibrate it!

For example, you may prefer reading your samples at the top of the meniscus and at 68F.
For that, you need to calibrate at the same temp (68F) and read the same way (the top of the meniscus) and note the deviation from the baseline (1.000 SG / 0% Brix). Then apply that same deviation to your samples, read at the top of the meniscus and at 68F.

Not to be obtuse, but how do i calibrate my hydrometer?

I get that i can read it how I want/consistently once i check it in distilled water, but unaware how to calibrate it like i can with my refractometer.

Or is the "calibration" with the hydrometer, really just learning how to properly read it when in distilled at right temps (or as the hydro was designed) ?

 

[Brewbuzzard]

It actually boggles my mind (a little) that there are some hydrometers calibrated/coming with instructions to read the top. I'm pretty sure that the height of the meniscus varies a little with wort properties. If so, that would mean those hydrometers are intended to measure an approximation. Maybe it's not big enough to make much difference. But it offends my delicate scientific sensibilities. I think I need a safe space.

I agree, viscosity should make a difference albeit may be small. But to make my life easier since I'm blind in one eye and can't see out of the other, I'll read the top of the meniscus.

 

[VikeMan]

Or is the "calibration" with the hydrometer, really just learning how to properly read it when in distilled at right temps (or as the hydro was designed) ?

Yes. measure in water at the correct temperature, note the delta from 1.000, and apply that when you take wort measurements.

 

[Birrofilo]

Not to be obtuse, but how do i calibrate my hydrometer?

Besides just noting the deviation from the right value in known conditions, one can actually "calibrate" a hydrometer.

Prepare a syrup which is somehow halfway of the normal density range. E.g. 100g sucrose in 1 litre total volume will give you a liter with a density of 1,0382.

Put your hydrometer in the syrup at 20°C (the temperature at which you consider the hydrometer calibrated. If you live in a hot country, that can be higher);

Note the deviation from 1,0382 (1,039 or a hair below).

Now:
if the hydrometer indicates a too high density (it "floats" too high), gently file the bottom until it reads good;
if the hydrometer indicates a too low density (it "dips" too much), add some transparent nail varnish to the top until it reads good.

That way you will have a "calibrated" instrument and you will not have to worry to remember to apply your correction.

I never tried this, because my only hydrometer works very well, but it's good to know. I am one of those who want an instrument to work as expected.

 

[bracconiere]

It actually boggles my mind (a little) that there are some hydrometers calibrated/coming with instructions to read the top. I'm pretty sure that the height of the meniscus varies a little with wort properties. If so, that would mean those hydrometers are intended to measure an approximation. Maybe it's not big enough to make much difference. But it offends my delicate scientific sensibilities. I think I need a safe space.

now i have to google meniscus correction factors.....

 

[IslandLizard]

Not to be obtuse, but how do i calibrate my hydrometer?

I was actually referring to calibrating the baseline, the 1.000 level/line.
Then relying on the manufacturer that the scale is correct at different gravities.

@Birrofilo took that to the next step by outlining a procedure to verify/correct the scale with an actually known gravity reading.
I'd be extremely careful filing/sanding/Dremeling a glass hydrometer, though.

 

[IslandLizard]

It actually boggles my mind (a little) that there are some hydrometers calibrated/coming with instructions to read the top. [...] it offends my delicate scientific sensibilities. I think I need a safe space.

I'm totally with you on that. Mind boggling and offending science.

In the many labs trainings we've had, you'd always read the surface of the fluid, (the bottom) of the meniscus, whether it was a hydrometer, a burette, a pipette, or a more complicated instrument. It was always the rule!
Similarly with mercury thermometers or pressure meters, the surface level is read against the scale, not down in the dip, at the edges.

 

[hotbeer]

It might be interesting to know what those hydrometers that show going by the top of the meniscus actually read in water when checking calibration.

Won't be the first time I've seen instructions that don't match what the reality is. Many times the document writers don't fully understand what the designer/maker is telling them and the designer/maker doesn't read what the documenter wrote.

Though I can also imagine someone making them without knowing what the rest of the world and science does and going by their own ideas.

 

[Soulshine2]

I have struggled with reading a hydrometer correctly since starting this hobby, and i'm sure there are even varying opinions on how to read it correctly. I know in the end it really doesn't matter as long as i use the same reading indicator at beginning & end, but unfortunately i was raised by an extreme perfectionist and i need to know for sure.

Please take a look at the pic if you will and tell me what the reading is..... (i'm reading it as 1.051)
View attachment 725265

looks like around 54-56 from here. if your reading is at temperature of calibration.

 

[Brewbuzzard]

Calibrate your hydrometer with distilled water at 60°F or whatever your instrument suggests. If the reading of 1.000 is at the top of the meniscus go with that. If the 1.000 is at surface level take the meniscus reading and add the difference to the meniscus from then on. For me it is difficult to read through the wort so I do the eye strain once.