How to Use a Refractometer to Measure Specific Gravity

A refractometer instantly reads gravity of unfermented wort, wine must, mead or fruit juice by measuring the degree that light passing through the sample is bent. Unlike a hydrometer, only a few drops are required for a sample. To use, apply 2-3 drops to the prism face, close cover, and look through the eyepiece while aiming your refractometer at a light source.

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[anthonybonnes]

I used your video in my Physics class today.  We are studying reflection and refraction so I was looking for examples of practical uses of Snell’s Law in industry.  A 30% sugar/water solution has an index of refraction of roughly 1.38 compared to a 80% solution with index of 1.49.  Thus the greater the amount of sugar in the water will cause the blue light to bend more and thus display higher on the scale—unfortunately class snowballed from there and we ended up spending most of class talking about different styles of beer and couldn’t get back on topic.  Too bad really, last semester’s went so well when I used Archimedes principle to explain the hydrometer.

[brynduffy]

rsg-32atc -> calibrated and numbers are sharp but the gravity line is blurred, shades from clear to deeper blue.

[sharpie]

Just used this puppy in our Blanchard grinder coolant at the job

[hezekiahadejuwon]

used this video for my coursework. quite helpful

[leesuschrist]

They sell the exact same thing on Amazon for about half what northern brewer has them.

[jhyland]

What other substances can the refractometer be used for? Looks like a very interesting tool.

[mythfpv]

Sorry, I am confused what is Gravity?

[skells]

I usually brew my wine to as close as 990 as I can. However the refractometer only go to 1000 as far as I can see? Can anyone please clarify? My conclusion is it won't work for me but maybe I'm missing something?

[noodle]

They are good, but I find you really need to mix your wort after the mash/sparge to get an accurate pre-boil gravity. Also note that if it reads in Brix & SG, I would ignore the SG as it's not accurate. It's been added purely as a guide. And with the Brix reading, it needs to be converted to Plato. I also wouldn't trust the alcohol calculators online either 😂 but apart from that...

[tubejoust]

you should mention that the SG scale on these is not accurate. You did mention that its an estimate though but were not clear on the inaccuracy of the printed scale.

[nunovyobeeswax]

I think I'll stick to my hydrometers, refractometers seem pretty limited.

[talontd]

Here because i want one for my reef tank, but i also make mead! Win win!

[stefanoberardi]

Buon giorno vorrei sapere come va una taratura

[ryukyudiver]

Can you use a Milwakee Instuments Digital refractometer? I have one that I use to measure salinity for my aquarium.

[maddyaurora]

so a refractometer measures gravity
the name refracto, shouldn't be measuring refraction or something logically related?

[seanyunt]

I've been using a hydro I purchased at my LHBS (for those of you who care).

A refractometer seems appealing as it uses a much smaller sample and less wort is wasted. However, for some slow working yeast strains I may take several SG samples. If these don't work as well once fermentation is underway, I'm not seeing the value over my hydro.

Can someone please elaborate?

[j.l.thurman]

Okay, so that's why I am not getting a good read. I just got a refractometer and i need first and last reads to determine SG. But I should be able to tell alch content with last read?

[Daniel-kzdf]

Can you provide the calculation or formulas on your website (in addition to the calc tool)? They are very handy tools, but understanding the algebra is something I'd like to know, and cannot find any references elsewhere. Thanks!

[Jelder]

@mmpantsless13 right on. Need more people like you in the world. We need to cut out this amazon and eBay bs. Support your local homebrew shop. Pay a little more but your gonna have quality service and a real person there to help u in a crunch. Well put in your comment. Cheers

[themoralshow]

Thank you❤️😃
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