Refractometer- how simple am I?

[Ben1]

Hey guys

I've never quite understood how to use my refractometer.

I batch sparge and try to mix prior to using my refractometer. Despite this, my readings always seem to be under and jump around a lot.

I have even tried to wait until the boil starts before measuring (thinking it will mix it further) but no luck.

How does everyone else measure their Pre-Boil Gravity?

 

[labels]

Why measure pre-boil? Your brewing software or paper calculations should give you an accurate estimation of SG for a specific volume for your grain bill. You can top up to keep the volume up during the boil or estimate boil-off for your system for a specific boil length. The best time to measure is after the wort has cooled going into the fermenter, then you can get an accurate measure of your efficiency compared to your estimated efficiency.

Also, take no notice of temperature compensated refractometers. That does not mean they compensate for temperature and adjust the visual measurement to the higher or lower temperatures, measure at the right temperature (usually 20C)

 

[manticle]

Measuring pre-boil is worth doing if you are trying to nut out where efficiency gains can be made and process flaws ironed out. Generally I don't but I'm not trying to isolate a problem.

oP - when you say it jumps around or is always under, can you be more specific? Is everything else (og, post boil volume, etc) where you want it or are there other issues?

 

[takai]

If you really want to know where your efficiency is going then you need to measure at every step of the process. Refractometers help here

Ideally for a refrac you want to put a couple of drops on the refraction plate and then wait for them to cool to 20c/roomtemp before measuring. Before you start you want to check for zero with plain water as your guide, that will give you a room temp baseline. If you have ATC then you can adjust your calibration at this point.

 

[Ducatiboy stu]

I always measure pre-boil. Gives me an idea of how well the mash & sparge went

 

[Black n Tan]

I also measure pre-boil gravity so I can make adjustments to hit target gravity. But like you I have found refractometer readings can be erratic: it can give you reading several points apart from the same sample. I suspect evaporation may be to blame or may be particulate matter under the glass alters the thickness of the film of fluid. So I now measure pre-boil (and OG) using a hydrometer. I place the sample in my glass measuring cylinder and place in a bowl of cool water for 10 minutes or so.

 

[Camo6]

Cooling your sample also helps you draw off clear wort. I've found muddy samples give muddy results.

 

[jc64]

Why measure pre boil?

So you have some idea how your beer will turn out! Bitterness, alcohol, and balance. Use a pipette draw a sample onto the refractometer and wait say a minute then read with confidence.

 

[Pogierob]

My refractometer makes me feel all sciency, I measure halfway through the mash, end of mash, after mash out (pre-boil) and then usually 2-3 times during the boil as a minimum.

It's overkill, yes, but makes me feel more in control cause I'm being sciency.

it also shows you exactly what is going on and when.

as far as random results, the only time I have massively varied results in usually after the mash, if i didn't give it a stir, the condensation that drops back to the top of the wort "thins" out the wort on top, a good stir usually sets this right. If you are getting varied results on your refrac with a constant sample then I would suggest you attempt to calibrate your refrac.

Perhaps you could make up a few DME mini worts of varied gravity and compare with a hydrometer.

 

[Ben1]

Thanks for the great feedback guys. I have my evaporation and efficiency generally sorted so generally works out ok in the end.

I'm probably not stirring enough and definitely not giving the sample much time to cool. Will try again and see how I go.

I thought there might be something I'm missing but it seems not. I found a BYO article that suggests you need to adjust (even for unfermented wort) and started doubting myself

 

[DJ_L3ThAL]

As takai mentioned, checking some distilled water and adjusting to 0.000 is important before every use. Brew day to brew day I've had adjustments as far as .010!!!

 

[MartinOC]

Brew day to brew day I've had adjustments as far as .010!!!

Oh, the HORROR! The HORROR!

*Rushes-off to buy more distilled water*

 

[DJ_L3ThAL]

Haha exactly! Who knows what I was brewing the days before I knew about the adjustment needing to be done every use............?

 

[stm]

What's the difference in SG between distilled water and normal Sydney tap water?

 

[DJ_L3ThAL]

Probably negligible in terms of the refractometers resolution, but it's a measuring device so for the sake of keeping a bottle of distilled water in my brewery of which I use 0.000005% of each brew day, I keep distilled. Not to mentioned the bottle of distilled is actually at the room temp, coming out of the mains it may be significantly cooler.

 

[Crakkers]

My refractometer makes me feel all sciency, I measure halfway through the mash, end of mash, after mash out (pre-boil) and then usually 2-3 times during the boil as a minimum.

I use my refractometer at 4 or 5 stages during a brew - 1st runnings, final runnings, pre-boil, during boil, post-boil, and a few more times just for fun.....I like to feel all sciency too!
I think my next purchase might be a stir plate. I reckon that would make me feel pretty sciency, though probably more in a 'Walter White' sort of way.
Why stop there? How about an array of 20 or 30 Bunsen burners under the brew kettle...............

 

[michaeld16]

Why measure pre boil?

So you have some idea how your beer will turn out! Bitterness, alcohol, and balance. Use a pipette draw a sample onto the refractometer and wait say a minute then read with confidence.

I like to adjust my hop additions if need be after mash out great use of a refractometer preboil

 

[BJB]

Why measure pre boil?

So you have some idea how your beer will turn out! Bitterness, alcohol, and balance. Use a pipette draw a sample onto the refractometer and wait say a minute then read with confidence.

:super: