Refractometer Readings Dont Match Each Other :-(

[jonw]

I brewed a batch of my Orval style yesterday - I use a refractometer for checking pre- and post-boil gravities. The trouble is, my readings are all over the place. Post boil varied between 10.2 and 12.6!

I have an alloy paddle I use for stirring the kettle. My method is:-

1) Stir kettle!
2) withdraw paddle and catch some of the runnings on the surface of the refracto
3) Flip down the lid as quick as I can
4) Read it.

Anybody got any idea why my readings vary so much, and what the best method is for using this tool?

Cheers,

Jon

 

[Fourstar]

Temperature can be an issue Johnw, i believe most are calibrated to read @ 20deg. i usually put 2.3 drops on the glass, leave for a min or 2. come back and observe at ambient temps.

 

[mika]

.... i usually put 2.3 drops on the glass....

Now there's precision for you :huh: , though I don't think I'm all that familiar with the SI definition of a 'drop'.

 

[Adamt]

Sounds Imperial to me *shakes fist*.

Consistency between readings can be affected by temperature, solids or bubbles.

 

[Sammus]

also if there is heat then a significant amount of water can evaporate from a couple of drops which will mess up your readings.

 

[jonw]

OK, it looks like I'm not doing anything obviously stupid. I might try using a small syringe to take a sample, let it cool, and measure that.

Cheers,

Jon

 

[Screwtop]

After stirring fill the syringe, I use the plastic eyedropper that came with the refrac kit to suck up some wort then squirt it back, do this about three times to make sure there is no other liquid (wort from previous readings or sanitiser) in the eyedropper. Then leave the sample to cool on the bench for 5 minutes before dropping 2 drops onto the refrac lens. Had this same problem with hot wort when I first started using my refrac.

Screwy

 

[Fourstar]

Now there's precision for you , though I don't think I'm all that familiar with the SI definition of a 'drop'.

Sounds Imperial to me *shakes fist*. Consistency between readings can be affected by temperature, solids or bubbles.

Sorry guys, i add 2 - 3 drops.

Note, these 'drops' are relatively even (or consistent) as they are added to the plate via a pipette.

 

[jonw]

I use the plastic eyedropper that came with the refrac kit...

I managed to lose mine fairly quickly. Better get another.

Cheers,

Jon

 

[Stuster]

After stirring fill the syringe, I use the plastic eyedropper that came with the refrac kit to suck up some wort then squirt it back, do this about three times to make sure there is no other liquid (wort from previous readings or sanitiser) in the eyedropper. Then leave the sample to cool on the bench for 5 minutes before dropping 2 drops onto the refrac lens. Had this same problem with hot wort when I first started using my refrac.

Screwy

I do exactly this as well. Gives me consistent readings as well.

 

[[email protected]]

It sounds to me like the temperature is what is causing your fluctuating readings as well. They do also make refractometers with automatic temperature compensation that don't require you to let the sample cool prior to measuring.

http://www.sperdirect.com/cgi-bin/item/300...actometer-w-ATC

 

[Sammus]

It sounds to me like the temperature is what is causing your fluctuating readings as well. They do also make refractometers with automatic temperature compensation that don't require you to let the sample cool prior to measuring.

http://www.sperdirect.com/cgi-bin/item/300...actometer-w-ATC

I'm pretty sure most here are using http://www.mashmaster.com.au/p/505647/refr...t-with-atc.html or similar which is advertised to be ATC.

 

[drsmurto]

Why not place a drop or 2 on the refract and let the wort cool under the glass thus negating evaporation?

 

[warrenlw63]

Why not place a drop or 2 on the refract and let the wort cool under the glass thus negating evaporation?

Be too easy. :lol:

To be honest since I stopped fly sparging 4 years ago my refractometer gathers dust in the cupboard. I just use my old-hat hydrometer to take the wort gravity.

Warren -

 

[Online Brewing Supplies]

Be too easy. :lol:

To be honest since I stopped fly sparging 4 years ago my refractometer gathers dust in the cupboard. I just use my old-hat hydrometer to take the wort gravity.

Warren -

We might be able to make a collection of discarded Refracto's.Hydro for me.I doesnt bother me to use 150ml of wort to get a more accurate result.I would bet money that my Hydro will give me a accurate result unlike my refracto.
My personal opinion for what its worth.
GB

 

[warrenlw63]

We might be able to make a collection of discarded Refracto's.Hydro for me.I doesnt bother me to use 150ml of wort to get a more accurate result.I would bet money that my Hydro will give me a accurate result unlike my refracto.
My personal opinion for what its worth.
GB

:lol: Yes you still need your hydrometer for the FG anyway. To be honest GB if it wasn't for the fact mine was given to me I would never have bothered.

One of those brewing whim items. Very much like a filter.

Warren -

 

[Online Brewing Supplies]

:lol: Yes you still need your hydrometer for the FG anyway. To be honest GB if it wasn't for the fact mine was given to me I would never have bothered.

One of those brewing whim items. Very much like a filter.

Warren -

Oh I have a filter too but Im too lazy to use it . I also have a machine that goes Ping but I dont know what that's for, looked good when I bought it though. :huh:
GB

 

[warrenlw63]

I also have a machine that goes Ping

:lol: :lol: Sorry GB I have a habit of getting "moderated" when I quote Python. h34r:

Warren -

 

[Online Brewing Supplies]

:lol: :lol: Sorry GB I have a habit of getting "moderated" when I quote Python. h34r:

Warren -

In that case bring me a shrubbery. :lol:
GB

 

[stillscottish]

One that looks nice?

Campbell
Ni! Ni! Ni! Ni!