More Refractometer Woes

[Hoochin'Fool]

I decided to get a Smartref. It sounds like it will get me pretty accurate gravities during brewing with a lot less hassle, and it should make less of a mess. It still uses a correction factor for fermented beer, but using the hydrometer to test beer is pretty painless.

I wish you luck with that. But that smartref device looks like it's going to be even more susceptible to hot-sample evaporation than your cheapo refractometer. Just my $0.02 tho

 

[Clint Yeastwood]

The company that makes it doesn't seem worried. Also, I now have a whole bunch of disposable droppers which cool quickly and don't permit much in the way of evaporation.

I don't think evaporation had anything to do with the problem. I think stirring up all that sediment was the real issue.

 

[DBhomebrew]

It might have been, but not stirring at all will cause another major issue. You must overcome stratification.

 

[Clint Yeastwood]

I think that is completely true.

 

[doug293cz]

It might have been, but not stirring at all will cause another major issue. You must overcome stratification.

I think that is completely true.

Stratification post-boil does not occur. Boiling effectively homogenizes the wort, and spontaneous stratification is not a thing in solutions.

However, if you add top-up water post boil, then you need to do something to homogenize the wort in order to get a valid SG reading.

Pre-boil, stratification is an issue if you sparge post mash.

Brew on

 

[Hoochin'Fool]

I'll be brewing next week, a simple recipe I've thoroughly nailed down, so my pre-boil gravity and volume SHOULD be spot-on. Soon as my 60 minute boil happens, I'm going to test a few drops on the refractometer (placing drops and closing the lens cover ASAP), and record. Then, once wort is chilled, will retest again with refractometer. If I wanted to be as scientific as possible, I'm gonna use several tests:

• Drops of hot wart straight onto refractometer
• Cool sample in eye-dropper, then onto refractometer
• Substantial sized sample (I'm thinking a cup or so), covered with a lid and put in fridge to cool, then drops onto refractometer for test
• Stir up the big sample and check more drops on refractometer again, to see if stratification sets in very fast.
• Use rest of the big sample to fill hydrometer test tube.

Anything else I should record?

So some test results from this morning's imperial stout...

Worst case: boiling wort, open spoon sample. If tested ASAP, got brix reading about 1.5 degrees higher than actual. After open spoon sample cooled, brix reading was 2.0 degrees higher than actual.

The eye-dropper was better: tested immediate (still hot), got brix reading about 0.5 degrees higher than actual. After cooling, brix was still 0.5 degrees higher than actual.

So "actual" was measured after the boil-kettle wort had cooled all the way down to 70F, and given a good stir. And it was 25 brix (as recipe software predicted).

Not sure how repeatable this is, my stove hits a VERY gentle boil, and lower gravity worts quite possibly would either show more or less effect from evaporation.

Each "brix degree" is about 4 gravity points

 

[Clint Yeastwood]

I hate metrology.