Refractometer or Hydrometer or Both ?

[hamster]

I bought a refractometer a while back but never really used it, guess I just trusted the hydrometer more. During todays brew however I took a whole load of readings and to me these are all wrong which is not helping my trust...

Can anyone make sense of these ? Do they need some adjusting ?

Pre-Boil

Refactometer
15% Brix
1.058 SG

Hydrometer
1.064 @27c
1.066 adjusted to 20c through calculator

Another refactometer reading taken from the hydrometer wort used above
14% Brix
1.054 SG

30 Mins into boil

Refactometer
14% Brix
1.054 SG

No hydrometer reading

End Boil

Refactometer
16% Brix
1.051 SG

Hydrometer
1.073 @20c

I'm beginning to think my Refactometer is broken !?

 

[henteaser]

Did you calibrate the refractometer with distilled water before use?

 

[hamster]

Did you calibrate the refractometer with distilled water before use?

No... Maybe this is where I'm going wrong although does that account for the gravity reading going down half way through the boil ?

I'm pretty sure the thing comes calibrated though...

I will now check, reading should be 1.000 with distilled water yes ?

 

[Dutto]

GOOD NEWS

I can calibrate a hydrometer with water from the tap. :thumb:

Hydrometers are relatively cheap. :thumb:

BAD NEWS

Hydrometers are VERY fragile (and to prove it I broke one last week!)

Refractometer's are expensive.

For me expense of a refractometer is the "Full Stop" of the comparison ... :thumb:

... which is why I always have two hydrometers available! :whistle:

 

[henteaser]

Yep, that's correct, there should be a little screw to adjust based on the distilled water.

What temperature was the wort? Even though mine is "ATC" I've found it can be well out compared to wort at 20c (same goes for my pH meter)

 

[hamster]

Yep, that's correct, there should be a little screw to adjust based on the distilled water.

What temperature was the wort? Even though mine is "ATC" I've found it can be well out compared to wort at 20c (same goes for my pH meter)

I did wonder what the little screwdriver was for :lol:

Wort would have been 75ish for the first set of readings, and from the boil for the rest. In saying that I take a sample via pipette which stood still for a while so temp would have dropped dramatically before readings taken...

 

[hamster]

... which is why I always have two hydrometers available! :whistle:

Haha so do I ! Plus 2 tubes for readings...

Fingers crossed though had both mine for 5 years + now...

 

[JapanBrew]

I mostly use my refractometer. I think they are more accurate if you know how to use them. But I'd say that your refracto SG markings are off. Quick rule is brix X 4 = SG.
The real problem is fermented wort. You have to use a calculator to adjust for alcohol.

 

[ericmark]

Glass is not a single commodity, there are many mixtures which produce glass, pyrex for example is made with a glass which has a very low coefficient of expansion, that's how it stands heat without breaking, it expands so little, OK that is an extreme, but the point is only the correction chart issued with the hydrometer your using is any good, there is no temperature conversion chart to fit all. I am sure you could take a sample of plain water and produce your own correction chart, but taking a conversion chart from a hydrometer made by x may not work with a hydrometer made by y.

I use a hydrometer to verify what I already know, temperature is controlled, I use same kits, and if it takes 20 day one time it is likely to take 20 days the next time. So the hydrometer only confirms what we already know.

 

[simon12]

I find refractometers just need calibrating so often you always need to check with a hydrometer as well anyway.