Reading a hydrometer - confused

[homebrewjapan]

What's the correct way to read a hydrometer?

This website - Stevenson Reeves - How to use a hydrometer - says:

The correct scale reading is that corresponding to the plane of intersection of the horizontal liquid surface and the stem. This is not the point where the surface of the liquid actually touches the hydrometer stem. Take the reading by viewing the scale through the liquid, and adjusting your line of sight until it is in the plane of the horizontal liquid surface. Do not take a reading if the hydrometer is touching the side of the hydrometer jar.

And they have this image to illustrate:

The instructions that came with my hydrometer tell me different, however. From the picture above, they say the reading should be 980 - ie, where the surface of the liquid touches the stem, not the intersection of the horizontal liquid surface. This contradicts everything I've read on the internet

Also, the hydrometer jar/tube is quite thin and the hydrometer always slightly touches the edge.

My beer is now at 1007 or 1006 depending on which point I should take. Bottling should occur at 1006 or less. The kit advises 4-7 days and it has been six days. Should I wait another day or is it ready?

 

[spitfire]

Start here https://www.homebrewtalk.com/f14/hydrometerly-challenged-108960/
then do a search if that doesn't answer your questions. lot's of info on how to read them

 

[Ballistic]

I sterilise my hydrometer and drop it in the bucket. Then I compensate for the water tension directly around the hydrometer.

 

[nebben]

Make sure that your test tube is as vertical as you can get it, and put your sample+hydrometer into that. The meniscus is the "collar" or bent up liquid around the edges of the tube, and around the hydrometer on the surface. It is caused by surface tension in the liquid. Your illustration shown above is correct - don't measure where the liquid curves up to touch the instrument, instead try to see where the sample is flat and try to figure out where that level of liquid would bisect the instrument's graduation marks.

If your hydrometer is different and calibrated to the meniscus instead of how all others are calibrated, fill the tube with ~70F (or whatever temp is says it is calibrated to) distilled water and re-measure. If all is well, it should be exactly 1.000.

Grab a couple or 3 sanitized turkey baster's full, put them in your test tube (usually the tube the hydrometer comes in works great), put in the hydrometer, spin the instrument to fleck off bubbles, and do the stuff above. Drink up the sample when finished.

 

[MajorTom]

There is conflicting information out there regarding how to read the meniscus. The instructions with my hydrometer say to read the upper part of the meniscus. Maybe it just depends on the calibration of the hydrometer when it was manufactured.

 

[bull8042]

There is a standard "proper" technique to read a hydrometer in use by the scientific community. However, they are probably not using the $0.47 "Made Somewhere Overseas POS" that we commonly encounter in homebrewing. For this reason, instructions differ from the norm.
As nebben stated, the best recourse would be to take a reading with YOUR hydrometer in distilled water at it's calibration temp and see where you should read YOUR hydrometer...... On the meniscus or level with the surface of the liquid.

 

[hungupdown]

Try it in tapwater at 20°C or 15°C, depending on what your hydrometer is calibrated to, and see what part of the meniscus is at 1.000.
A bigger factor might be the temperature correction factor needed. For mine, the Loxford wine and beer tester, it's +2 for brew at 25°C (77°F).

The Loxford is a hydrometer in a tube, with a suction bulb (a bit like a baster

). Sadly I don't think they're made any more.

 

[IslandLizard]

The Loxford is a hydrometer in a tube, with a suction bulb (a bit like a baster). Sadly I don't think they're made any more.

That surely is a curiosity! I'm surprised it survived the test of time.
I would keep it in a safe place, for posterity, or some museum perhaps... not for daily use.

Does it drip/leak when pulling it out of the liquid you're measuring? Perhaps there's a valve in the bottom of the "siphon" to prevent that.
BTW, congrats on posting to a thread that's been dormant for over 16 years!

 

[TexasTea]

In all the chemistry courses I slept through from junior high all the way through college, they always said to read the meniscus from the bottom (.980) per the illustration.

My dad had one of those suction hydrometers (Loxford) and used it for testing antifreeze concentration.

 

[mac_1103]

In all the chemistry courses I slept through from junior high all the way through college, they always said to read the meniscus from the bottom (.980) per the illustration.

How would you know? Since you were sleeping and all?

 

[Snuffy]

You crazy kids with your sundials and your abacuses...


abacusses... abacusi... abacadabras?

 

[TexasTea]

How would you know? Since you were sleeping and all?

Skool Daze Pro Tip- Always date girls in your class with excellent note taking skills.

 

[odie]

I think that if you read it the same way every time...it will be accurate for what you need.

it's really about OG vs FG...

 

[Snuffy]

You should ask for a Tilt for Christmas and use the hydrometer as a fishing bobber.

 

[hungupdown]

That surely is a curiosity! I'm surprised it survived the test of time.
I would keep it in a safe place, for posterity, or some museum perhaps... not for daily use.

Does it drip/leak when pulling it out of the liquid you're measuring? Perhaps there's a valve in the bottom of the "siphon" to prevent that.
BTW, congrats on posting to a thread that's been dormant for over 16 years!

Hadn't looked at the date, as it had come up under 'recent posts'.

Now taking very great care of it. Having broken my first one after around 30 years use, while hydrometer was removed from tube for cleaning. Found replacement from a shop (that's closed now) who had some "old stock'.

No valve at bottom, just a narrow silicone nozzle.
The shape of the flare in the glass tube, means it will sit on the neck of a 1 gallon demijohn. With the nozzle under the normal liquid level.
If its lifted out after filling, suction from escaping drips, would then give a low reading. But if you pinch the nozzle, the reading will stabilise. I do this for readings from opaque 23l fermenters.

 

[tracer bullet]

I've found the "right" way to read it actually depends on the manufacturer. I'd have assumed it was 1-size-fits-all for the method, but no, different company's instruction manuals will actually give different methods.

I like the idea of checking it in distilled or RO room temp water and finding what appears to show 1.000 and then just sticking with that method.

Also RDWHAHB because a point or two either way will not be detectable on the palate of any normal human being.

 

[redrocker652002]

Wow, cool. I learned something here. I was reading where the liquid was touching the tube, so with that said, I was off to a point where my actual OG was probably a lot closer than I thought.

 

[marc1]

What's the correct way to read a hydrometer?

This website - Stevenson Reeves - How to use a hydrometer - says:

The correct scale reading is that corresponding to the plane of intersection of the horizontal liquid surface and the stem. This is not the point where the surface of the liquid actually touches the hydrometer stem. Take the reading by viewing the scale through the liquid, and adjusting your line of sight until it is in the plane of the horizontal liquid surface. Do not take a reading if the hydrometer is touching the side of the hydrometer jar.

And they have this image to illustrate:

The instructions that came with my hydrometer tell me different, however. From the picture above, they say the reading should be 980 - ie, where the surface of the liquid touches the stem, not the intersection of the horizontal liquid surface. This contradicts everything I've read on the internet

Also, the hydrometer jar/tube is quite thin and the hydrometer always slightly touches the edge.

My beer is now at 1007 or 1006 depending on which point I should take. Bottling should occur at 1006 or less. The kit advises 4-7 days and it has been six days. Should I wait another day or is it ready?

Mine is the same way - if the directions say it's calibrated at the top of the meniscus, then that's where to read from. If there's any doubt, read it in water at the calibration temp, (as posters have mentioned) to make sure that the directions are correct.

Many (most?) hydrometers are read from the bottom line instead, which is where the confusion is coming from.

You can help prevent it touching the sides if you fill it all the way to the top (I put it the hydrometer jar in a small plastic box to contain the spillage) and give it a spin.

 

[Kickass]

Meniscus, no meniscus, whatever. The bigger point is, read it the same way every time AND read the correct scale. Lots of new hydrometer users get confused on which scale to use. One last thing, understanding where the decimal goes on the SG scale.

Those are more important than trying to gnats butt between 2 SG points.

 

[Alfgs]

I read it like the picture says to do it but the way I see it you use the reading before and after fermentation to calculate your abv, so as long as you read it the same, the abv will be correct enough.

I.e. 1.100 down to 1.000 is the same as 1.102 down to 1.002.