Refractometer usage

[malt junkie]

Just get a mass-spectrometer and be done with it!!?!

 

[Lyrebird_Cycles]

How does natural daylight fit in with that?

Broadens the border as the different wavelengths refract at different angles (that's how a prism makes a spectrum).

 

[Lyrebird_Cycles]

Just get a mass-spectrometer and be done with it!!?!

Don't laugh, I came very close to scoring a Hewlett Packard GC-MS package on Ebay a few years ago for under $7k. Probably a good thing I missed out, would very likely have been a source of domestic disharmony.

 

[Ducatiboy stu]

Just get a mass-spectrometer and be done with it!!?!

Bulk buy !

 

[Bribie G]

Another thing nobody's mentioned is that refractometers are only accurate when used with a monochromatic light source, classically the D line of a sodium vapour lamp (589 nm). An amber / yellow LED is a close approximation.

That's why I'm thinking of moving back to the UK where sodium street lights are almost universal. When I was a kid I always thought that streets were meant to be yellow after dark.

 

[Midnight Brew]

BrixCalc is a great free app for refractometer readings. Advantage being on your phone is you'll usually have your phone in your pocket when you're doing brewing tasks in the garage.

 

[Lyrebird_Cycles]

That looks pretty good. ATC up to 100 deg is awesome.
How much did it set you back?

I bought mine years ago, the price has come down since. They are now a little over $300 on epay.

 

[Lyrebird_Cycles]

Mate it is very easy- no need for spreadsheets etc just use this and punch in your numbers:

http://www.brewersfriend.com/refractometer-calculator/

So you had a SG of 10.5 and FG of 5. Put those numbers into here and voila- 10.042 SG and FG 1.010. same as your refractometer.

edit- use part 2. First part gives SG in Plato, 2nd part gives you your alcohol adjusted reading.

I think that would only be the case if the 10.5 was the refactometer reading pre correction.

Matplat, correct me if I'm wrong but my reading of the original post is that the 10.5 was the actual OG (hydrometer reading).

 

[pcmfisher]

I just wait for the airlock to stop bubbling......

 

[Matplat]

I think that would only be the case if the 10.5 was the refactometer reading pre correction.

Matplat, correct me if I'm wrong but my reading of the original post is that the 10.5 was the actual OG (hydrometer reading).

Yep that's correct, I converted backwards in order to use a calculator.

I missed droopy brews original post though, and I am somewhat confused as to why that calculator gives the 1.010 FG, even applying the 4% correction it gives 1.009 which doesn't follow my original calculation...?

 

[Mardoo]

I just wait for the kitten to stop meowing......

FTFY

 

[Ducatiboy stu]

Bloody kittens...they keep you awake at night

 

[Droopy Brew]

Yep that's correct, I converted backwards in order to use a calculator.

I missed droopy brews original post though, and I am somewhat confused as to why that calculator gives the 1.010 FG, even applying the 4% correction it gives 1.009 which doesn't follow my original calculation...?

OK so the 10.5 was with a correction factor? If you have used that tool with the correction factor for both and you are 1 pt away from your hydro reading that is pretty close. I've always found the tool to be pretty spot on when I compare refrac and hydro.

 

[Matplat]

Yeah, if I had used that calc instead of the one on my phone, I wouldn't have started this thread...

But then DBS wouldn't have got his kitten fix, so all is not lost.

 

[Ducatiboy stu]

But then DBS wouldn't have got his kitten fix, so all is not lost.

I am more of a Rice Gulls man

 

[barls]

Bulk buy !

wheres yob?

 

[Matplat]

Well, I am unimpressed to say the least. Did a brew last night and monitored gravity along the way, or attempted to at least. It was almost impossible to remove all the air bubbles from the sight glass, which I'm guessing affected readings fairly well.

I was monitoring the last runnings from the malt pipe, and the gravity seemed to be dropping, but then it jumped up at the end??? Then i measured the pre and post boil SG, 1.043 and 1.050 respectively. Double check the OG with the hydro, 1.044.... can't trust the measurements at all so it's basically useless.

How do bubbles affect the reading? I would have thought they would make it lower than actual? Should have checked for myself last night...

 

[Ducatiboy stu]

Honestly........

Refractometer suck. Sorry, but they do. I made the mistake of buying one in the big refractometer rush of 2000 & something. They are a bit of a ****

First thing i noticed was that whereas when calibrating with water the line was perfectly defined, it was now much more blurry. I assume this is due to cloudiness from suspended yeast?

Stick with a Hydro. B)

My kids ended up using it to amuse themselves with the flappy bit at the end....and using it as a bit of a thing to look at small objects with.

 

[nala]

Well, I am unimpressed to say the least. Did a brew last night and monitored gravity along the way, or attempted to at least. It was almost impossible to remove all the air bubbles from the sight glass, which I'm guessing affected readings fairly well.
I was monitoring the last runnings from the malt pipe, and the gravity seemed to be dropping, but then it jumped up at the end??? Then i measured the pre and post boil SG, 1.043 and 1.050 respectively. Double check the OG with the hydro, 1.044.... can't trust the measurements at all so it's basically useless.
How do bubbles affect the reading? I would have thought they would make it lower than actual? Should have checked for myself last night...

Old saying... poor workman blame tools.

 

[Matplat]

Nothing wrong with the workmanship, I made a delicious wort that is happily fermenting away right now.

The information provided by this tool was unreliable is all I'm saying.