How to use a refractometer?

Just got my refractometer in the mail. Just wanted to get the proceedure down so i get proper measurements and properly care for it.

Assuming its an auto temp calibrated model...

Calibrate to 0.0 brix/plato with distilled or RO water that is roughly the same temperature as the wort sample. That's the ATC part of it...the calibration solution needs to be the same temp as the 'live sample' since large differences will skew the sample reading. Luckily you only need like 3 drops of wort, which is EASY to cool to 70F.

Always take a reading under strong light. I go right underneath a lightbulb for mine.

I have been thinking i really want a refractometer... Are they really as cool as I'm dreaming they are?

I love mine. I picked one up from AHS which has OG on it. So it saves me doing the quick calculation from Brix each time I use it.

Refractometers are simple. Calibrate to the directions, add 3 drops of liquid (wort or must) and read under light source. I got the BRIX and specific gravity model.

Hydrometer is a just in case tool now.

I love my refractometer! They are as cool as you imagine

I love mine, it makes getting a pre-boil gravity ready a breeze. I haven't missed hitting my gravity since I started using it. But get the one that has the gravity readings. Mine just has the brix readings and I have to reference a convertion chart every time I use it.

Set it on stun and watch the perimeter for romulans.

I've used my refractometer for one brew (just got it last week). I do not know how, or why, I brewed without one of these before. Makes everything sooooo much easier.

I use a refractometer for my reef tank, but we are measuring sugars in the wort here and not salt. How does this affect the reading?

I don't think it should matter whether it's sugar or salt a refractometer measures the specific gravity which is merely a measurment of relative density, whether its dissolved salt or sugar in water, a solution with a SG of 1.020 is the same from SG purposes.
How yeast is able to ferment those solutions is obviously quite different but your "salt water" refractometer should take accurate wort measurements as well.

Veinman said:

I don't think it should matter whether it's sugar or salt a refractometer measures the specific gravity which is merely a measurment of relative density, whether its dissolved salt or sugar in water, a solution with a SG of 1.020 is the same from SG purposes.

Click to expand...

Not quite. The thing measures the angle of refraction of light due to either sugar or salt in the liquid. it's not measuring "gravity" directly like a hydrometer is.

From what I read there is a difference between refractometers that are meant for sugar solutions vs those that are meant for salt solutions.

Ooops my bad, how does one know which type they have then?

Also when using during brewing you should be cooling your sample to the temperature of the RO water you used to calibrate right? Do you take a thermometer reading of a tiny sample or just let it sit for a few minutes to adjust to room temperature (I assume a few drops would adjust very quickly)

malkore said:

Calibrate to 0.0 brix/plato with distilled or RO water that is roughly the same temperature as the wort sample. That's the ATC part of it...the calibration solution needs to be the same temp as the 'live sample' since large differences will skew the sample reading.

Click to expand...

Is that right? I haven't used one before but had been doing some reading because I was thinking about picking one up.

I thought the ATC meant that if you take a reading in a room with 70° ambient temperature or a room with 80° ambient temperature it wouldn't matter. Whereas if you don't have ATC you have to compensate for the ambient temperature of the room.

I thought the wort didn't have to be cooled down before measuring (regardless of if you have ATC) because when you put a couple drops of hot wort on the refractometer, the much larger thermal mass of the refractometer cools off those drops extremely quickly..

impur said:

I use a refractometer for my reef tank, but we are measuring sugars in the wort here and not salt. How does this affect the reading?

Click to expand...

I've owned a salt tank and used a different refractometer for that. Depending on the scale yours reads, it might work.
The principle is exactly the same...pure water is 0.0 brix/plato/SG, so both salt and sugar will raise the gravity.

I think the 'typical' reef refractometer doesn't have a scale that goes high enough for our thick worts. I could be wrong though!

*edited to add*

That was my interpretation of what I read about ATC being you needed to calibrate it at the temp its going to be used at. You are right that you don't really have to 'actively' cool the wort since 3 drops just doesn't carry enough thermal mass. The plastic dropper probably sinks 90% of the heat from the 1ml I draw in to dropper onto the prism.

tvtoms said:

Set it on stun and watch the perimeter for romulans.

Click to expand...

Lol God Damn Romulans

malkore said:

That was my interpretation of what I read about ATC being you needed to calibrate it at the temp its going to be used at. You are right that you don't really have to 'actively' cool the wort since 3 drops just doesn't carry enough thermal mass. The plastic dropper probably sinks 90% of the heat from the 1ml I draw in to dropper onto the prism.

Click to expand...

I did an experiment today as I was making a starter.
1. I mixed up my starter and took a hydro-reading at 1042 it was at room temperature (approx 70)
2. Took a refractrometer reading and got the same 1042 number
3. Took the sample and boiled it in the microwave once it boiled I immediately pulled it out and took a refractrometer reading and got 1042

So it appears that my refractrometer will give the same reading regardless of the wort's temperature, mine was off ebay and listed as having auto-temperature correction for what it's worth this experiment should tell you if your's will work the same.