[Kaiser]

When reading the hydrometer, you have to ignore the "meniscus," that little bit of liquid that "curves" up the side of the hydrometer, and look at the actual fluid level.

I found that this depends on the hydrometer. Mine for example reads calibration temperature water correct at 1.000 when I read the top of the meniscus.

Kai

[Slowbrew]

When reading the hydrometer, you have to ignore the "meniscus," that little bit of liquid that "curves" up the side of the hydrometer, and look at the actual fluid level.

I found that this depends on the hydrometer. Mine for example reads calibration temperature water correct at 1.000 when I read the top of the meniscus.

Kai

The hydrometer I have at the moment reads .003 below actual.

Paul

[bluesman]

One thing to take into consideration is calibration. When calibrating your hydrometer in distilled water at 60F take note of the reading and how you are taking your reading on the hydrometer. These two things are important for two reasons, one being a correction factor (if present) and secondly the way you are reading the hydrometer (above the liquid or at the meniscus). When using the hydrometer to measure the gravity of the wort make sure to apply the correction factor (if necessary) and take the reading the same way as was done during calibration.

[a10t2]

When calibrating your hydrometer in distilled water at 60F...

Assuming your hydrometer is calibrated at 60°F.

The little slip of paper that came with the hydrometer will tell you the calibration temperature, and probably whether to read the top or bottom of the meniscus.

[bluesman]

When calibrating your hydrometer in distilled water at 60F...

Assuming your hydrometer is calibrated at 60°F.

The little slip of paper that came with the hydrometer will tell you the calibration temperature, and probably whether to read the top or bottom of the meniscus.

True, but I haven't come across one that wasn't...not that you're wrong. Just sayin.

[a10t2]

True, but I haven't come across one that wasn't...not that you're wrong. Just sayin.

Admittedly, I've only bought two of the typical homebrew-shop $8 models, but they were both calibrated at 20°C/68°F. Probably just different brands. The ones we have at the brewery are calibrated at 59°F.

[Kaiser]

My hydrometer is a bit off as well, but I’m correcting for this and temperature, buy using a customized table like this. The customization allows it to account for the offset that you see when you read plain water:

http://www.braukaiser.com/documents/hydrometer_conversion_tables.pdf

I have one for the 0-30 Plato hydrometer and one for the 0.990 – 1.020 hydrometer on the front  and back of my brewing log book. When I take a reading I also take the sample temperature and find the corrected value that I then write into my notes.

Kai

[bluesman]

True, but I haven't come across one that wasn't...not that you're wrong. Just sayin.

Admittedly, I've only bought two of the typical homebrew-shop $8 models, but they were both calibrated at 20°C/68°F. Probably just different brands.

You are correct in that there are different calibration temps for hydrometers. I think 60F and 68F are probably the most common for brewers and vintners.

[punatic]

Just a thought...  how important are exact hydrometer readings?  Could you tell the difference in a beer with an original gravity reading of 1.048 that should have been 1.052?  Is an error of 0.004 gravity points significant?  Can $10 hydrometers be counted on to be accurate to 0.002 gravity points (the smallest graduation on most HB hydrometers)?

I know several brewers who brew by recipe only and never take specific gravity readings.  Their beers taste just as good, time after time, as any I've tasted where the O.G. and T.G. are known.  I kid them that their brewing is like driving a car without a speedometer.

I use the flask and scale method because I can and it's convenient.  I work with lab equipment daily.  More often I use it to calulate ethanol content.

[Kaiser]

Just a thought...  how important are exact hydrometer readings?  Could you tell the difference in a beer with an original gravity reading of 1.048 that should have been 1.052?  Is an error of 0.004 gravity points significant?  Can $10 hydrometers be counted on to be accurate to 0.002 gravity points (the smallest graduation on most HB hydrometers)?

It think it is more important to have consistent hydrometer readings than it is to have precise readings. After all you want repeatability. Precise readings are nice to have if you want to exchange that data with other home brewers.

I think most hydrometers suffer from not being correctly calibrated to at the 1.000 mark. Once that is correct the only other thing that matters is the diameter of the tube with the scale. This will determine how far the hydrometer rises as the sugar content increases. I think that diameter might be fairly well controlled when they make the glass stock from which hydrometers are blown.

Kai

[bluesman]

It think it is more important to have consistent hydrometer readings than it is to have precise readings. After all you want repeatability. Precise readings are nice to have if you want to exchange that data with other home brewers.

+1

Repeatability is key to understanding one's process variability. I also like to know how accurate my readings are as well so they are both important to me.

[Hokerer]

The hydrometer I have at the moment reads .003 below actual.

Paul

Both of mine read .003 above actual.

[Janis]

in a previous post i said i was brewing my first batch, well now i am finished and i don't know how to read this hydrometer.  the paper inside the tube was not very helpful.  can anyone help please?  thanks


http://s1118.photobucket.com/albums/k605/jth138/?action=view&current=gravity2.jpg

http://s1118.photobucket.com/albums/k605/jth138/?action=view&current=gravity2.jpg

http://s1118.photobucket.com/albums/k605/jth138/?action=view&current=gravity3.jpg

Hi,

You should check out the AHA Homebrewopedia for procedures like this.  There is a procedure called Specific Gravity Measurements (http://wiki.homebrewersassociation.org/SpecificGravityMeasurements) that may help. 

Also, the AHA Homebrewopedia is a great way for homebrewers to pass on their expertise to those who are less experienced.  Check it out!

Cheers,
   Janis

Janis Gross
National Homebrew Competition Director
AHA Project Coordinator
janis@brewersassociation.org

[denny]

THIS!  ^^^^^^^^^

[bluesman]

THIS!  ^^^^^^^^^

+1

Thanks Janis...I learn something everyday here. I didn't realize there were instructions for this on the homebrewopedia.

I like to keep my hydrometer and thermometer together as I have forgotten to measure the temp of the wort prior to reading the hydrometer and the temp is required to correct the SG reading.