Refractometer Issues

[Darren]

If refractometer readings were always correct then the excise agents would use them. Apparently they use hydrometers. I wonder why??

Refractometers give nothing but ball park measures and are entirely reliant on the fermentability of the wort (for an equation).

As we would all be aware, fermentability is an individual characteristic of each beer.

Refractometer= ball-park. Hydrometer= closer.

cheers

Darren

 

[alexbrand]

I'm pretty sure refractometer readings are still affected by the presence of alcohol but I'm not sure by how much. Try measuring some vodka or metho sometime to see. Or, spike a wort sample with metho and see what happens.

Take 10 mL of disdtilled water and add 0.5 g of sugar. Now take 10 mL of an aclohol/water mix (1:2) and add again 0.5g sugar. Than with a 1:10 mix. Measure and have fun!

Refractometer= ball-park. Hydrometer= closer.

For me it's close enough. I don't work so exactly. No need to do so .

Alex

 

[Zwickel]

For me it's close enough. I don't work so exactly. No need to do so .

Alex, I never use a Refractometer whilst fermenting, thats more a guess-o-meter than a meter.
I bet, if I stick the finger in the fermenting wort and lick at it, I would be closer with the result than a refractometer

 

[alexbrand]

Alex, I never use a Refractometer whilst fermenting, thats more a guess-o-meter than a meter.

Hey Zwickel!

Well, that is your opinion. It's okay! No worries.
Mine is different. As long as you know how a refractometer works and what influences the values measured with it, you can interprete the result. It'n not only the alcohol that affects the values. All soluted and unsoluted matters refract the light different from a sugar/water solution. This device works best with aqua purificata. I know.

Cheers,

Alex

 

[drsmurto]

Your og sample is easy to deal with, it is a mixture of water and malt sugars.

Alcohol content affects both the refractive index and the density, so both the refractometer and hydrometer readings will be skewed once you start taking readings after pitching. Neither will give the correct answer.

You could always go all white coat, grab a known volume of wort in a beaker, simmer gently to evaporate the alcohol, then top up with distilled water back to your known volume, stir well, cool and then do a refractometer sample and a hydrometer sample.

Sounds like something to do on a slow day in the lab......