Specific Gravity And When Do You Know It Correct?

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The meniscus is the slope in the fluid due to surface tension of the fluid being measured as it contacts the edges. The standard way is to measure the bottom of the meniscus, that is the level lower bit, not the high part where it actually contacts the hydrometer scale. Different chemicals alter the surface tension, but not where the bottom of the mensicus occurs.

So measure from the bottom of the meniscus, not the top. Except for fluids that bulge the other way, like mercury.
 
Hi POL,, actually you need to look carefully at the small print on the inside of the hydrometer to see whether it has been calibrated from the top or bottom of the meniscus. The precision Carlton Brand units we sell to the micros are indeed calibrated to the TOP of the meniscus and at 20C. This makes reading viable when measuring darker worts (and beers).

I do agree that most of the HB hydrometers are calibrated to the bottom of the meniscus though.

Wes
 
On the refractometer note, there's a lot of 0-32% brix ones listed on eBay. Is this the sort of unit I should get? I'd be going for one with automatic temperature compensation.

What was the group buy price? The ones I speak of are listed at US$43 and US$13 postage.

Cheers,
Nick
 
NRB said:
On the refractometer note, there's a lot of 0-32% brix ones listed on eBay. Is this the sort of unit I should get? I'd be going for one with automatic temperature compensation.

What was the group buy price? The ones I speak of are listed at US$43 and US$13 postage.

Cheers,
Nick
[post="49529"][/post]​

There have been two group buys. The last one was here. I got one and it works fine.
http://www.aussiehomebrewer.com/forum/inde...l=refractometer
 
1 Brix = 4 sg points, so a 0-32 Brix refractometer will go from 1.000 to 1.128 sg

This is the range most homebrewers opt for.
 
wessmith said:
Hi POL,, actually you need to look carefully at the small print on the inside of the hydrometer to see whether it has been calibrated from the top or bottom of the meniscus. The precision Carlton Brand units we sell to the micros are indeed calibrated to the TOP of the meniscus and at 20C. This makes reading viable when measuring darker worts (and beers).

I do agree that most of the HB hydrometers are calibrated to the bottom of the meniscus though.

Wes
[post="49527"][/post]​

Thank you Wes. For a moment I thought I was wrong as usual. The instructions with my hydrometer is as you say. I was not aware there are other types out there...

:chug:
 
I can still visualize a high school science teacher saying read from the bottom of the meniscus.

Thanks for the clarification. Always read the fine print.

All of the cheap homebrew hydrometers I have seen are from the bottom.

Those fancy expensive ones would sure make the stouts easier to read.
 
Peter Shane said:
[Each to their own. I do happen to agree with you accept I also like tasting my sample to see how it is developing and to detect any off flavours god forbit. Since I like tasting my sample I will not be saving any beer making the cost of the reflectometer even more costlier.
[post="49498"][/post]​

There is you nothing to stop you drawing of a larger sample when you use a refractometer :) , except maybe will power. I tend to draw off about half of what I would need for the hydrometer tube, which still gives a decent sample to taste.

The refractometer is a lot easier to use and read, harder to break, and has automatic temperature correction.

As far as the fg reading is concerned - I use the refractometer tool in beersmith, which seems to work just dandy.

Refractometers and beer brewing software :eek: , bet the missus never regrets the day she got me the Coopers starter kit so as I could save a little bit of money :lol:
 
For those of you wanting to purchase refractometers. Don't get hung up on whether it's got temp. compensation or not. In other words if the price is good and it doesn't have temp. compensation, don't let that dissuade you.

Samples are supposed to be read at 20c. If you've seen the amount of liquid that goes onto a refractometer it only equates to a couple of drops. Cools down in seconds. That notwithstanding just sit your sample on a teaspoon and touch the bottom of the teaspoon in some cold water if you're so inclined. Frankly I don't bother.

Mine's not temp. compensating and the readings don't change from when I put the sample straight on to the reading being checked five mins. later.

Just remember to calibrate it each brewday with distilled water. I've noticed they can go out from time to time (well mine does anyway).

Warren -
 
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