Refractometer help!

[SaffaStu]

Sooo... Ive got a refractometer. It's the type that is calibrated with only an abv % scale, so when I look through it I don't see °brix or SG, only abv% from 0 - 80%. My question is this: are these accurate, and am I using it correctly. I've tried to measure a batch of Mead I have settling ( fermentation is done, and it's stabilized), which according to my records and readings during primary, should at maximum have got to around 12%, however, when I check with this abv refractometer I gives me a reading of nearly 27%!!! What's going on! This reading was taken before any back sweetening, and FG was 1.000.
The strangest thing is that when I measure some Jack Daniels whiskey it tells me true, exactly 40%.
I'm hoping one you can shed some light on this, it's doing my head on!

 

[thepatchworkdoll]

Im afraid its a spirit refactometer you have. Its used foir measuring spirit not beer.
Regards
Patch

 

[SaffaStu]

Im afraid its a spirit refactometer you have. Its used foir measuring spirit not beer.
Regards
Patch

Aha. So no good for wine or cider either?

 

[dmtaylor]

Really only good for moonshine.

 

[Agentgonzo]

You could still use it. You'll just need to 'calibrate' it yourself. Put some wort in there that you've measured with your hydrometer. You'll then know that whatever it reads in ABV is equivalent to whatever you measured in SG. from there it's a simple calculation for all future readings

 

[peebee]

Ahhh ... the problems of using an instrument designed for a different purpose to measure something else entirely different. But setup right and understanding them a little bit and they don't do a bad job.

Before following @Agentgonzo's sound advice, I'd do a quick check: Put a drop of plain water (room temperature like the instrument). The indicator bar should be close to the bottom (this will be the 1.000 SG - zero Brix - datum). Try again with some sugar solution; the indicator should rise up the scale.

I've a sneaking suspicion an instrument meant for alcohol-in-water might do something else!

And don't forget if measuring a fermented liquid, the reading will be skewed by the alcohol content (there are online calculators to correct it). Beer brewers must calibrate their instruments too. Not by much, and the calculators altering the Brix reading to SG probably does it for them (Brix expects a sucrose solution, not maltose). That comment was just to rub in how "alien" these instruments are for measuring "SG".

 

[SaffaStu]

Ahhh ... the problems of using an instrument designed for a different purpose to measure something else entirely different. But setup right and understanding them a little bit and they don't do a bad job.

Before following @Agentgonzo's sound advice, I'd do a quick check: Put a drop of plain water (room temperature like the instrument). The indicator bar should be close to the bottom (this will be the 1.000 SG - zero Brix - datum). Try again with some sugar solution; the indicator should rise up the scale.

I've a sneaking suspicion an instrument meant for alcohol-in-water might do something else!

And don't forget if measuring a fermented liquid, the reading will be skewed by the alcohol content (there are online calculators to correct it). Beer brewers must calibrate their instruments too. Not by much, and the calculators altering the Brix reading to SG probably does it for them (Brix expects a sucrose solution, not maltose). That comment was just to rub in how "alien" these instruments are for measuring "SG".

Thanks for the advice. The refractometer was actually a gift, which is getting returned and replaced with a vinometer. I use a hydrometer when brewing/fermenting, and just wanted something to check alcohol levels AFTER all is done, as my wife swears blind that the wine made her has more alcohol than what I'm claiming!

 

[peebee]

Thanks for the advice

Pleasure!

If we wait long enough someone will chip in saying you need a good "hydrometer".

A "hydrometer"! Okay, measuring "SG" isn't quite as alien for a "hydrometer" (buoyancy) as a "refractometer" (light refraction).

What you really need is a pykn...

Okay, so I'm going off on one again. I'll shut up now and climb back in me box.

 

[SaffaStu]

Now you've got me...what's a pykn!?

 

[peebee]

...ometer.

You do know that encouraging me about "pyknometers" will possibly get you banished from the forum?

The "pyknometer" is only half the story. It provides a measured quantity (it's a bottle with a hole in the stopper). You also need some fairly accurate weighing scales (reliable to two decimals of a gram, cost about £35-40 or more). From these you can get density (in, say, grams per millilitre). Which you divide by density of water (0.9982g/ml at 20°C) to give you "relative density". "SG" is "relative density".

Will I go on? I can you know. But most people start to gibber and roll on the ground demanding I stop. So ... ?

 

[SaffaStu]

You do know that encouraging me about "pyknometers" will possibly get you banished from the forum?

We'll leave it at that then! I do understand your explanation though, thank you. Don't think I'll be going down that route, I don't need that level of accuracy. As long as my brews have alcohol in them, I'm happy