Refractometer vs. Hydrometer Video

[Bobby_M]

[ame=http://www.youtube.com/watch?v=KaonMYRODks]YouTube - Brewing with Bobby M Refractometer vs. Hydrometer[/ame]

Don't mind the year old Flanders barrel in the background.

 

[avaserfi]

Pretty cool, makes me want a refractometer. What would be the easiest way to just pull a couple drops from a carboy though? Do you just take some with the baster put a couple drops in and taste the rest?

 

[Bobby_M]

They make really long pipets that you'd dip in and hold your thumb over the end before pulling it out. A drinking straw would work in a pinch. I look at refractometers as fast and easy when you DON'T want to taste the sample. If you're going to drink a few ounces, you might as well go hydrometer. I didn't really want to recommend one over another because they both have their place, but I hope the video shows the pros/cons.

 

[IrregularPulse]

nice video. I would like a refractometer to make OG sample easier but was displeased with not being able to use it after fermentaiton. Thanks to this brew sheet I get to spend another $50. Thanks Bobby-M!

I know in your video you say 0-32° is good but is 0-70° okay as well? or too broad a range for our use?

 

[Revvy]

Wow great vid...you convinced me.

Especially since I could make out the numbers on the refractometer through the viewfinder of your camera...I'm sure my eyes could see it as well naked.

Question...when drawing a pipette sample for preboil gravity, where it's come out of the mashtun @ around 150ish degrees, how long to you have to let the sample cool before dropping it onto the lens? You mentioned something about the refractometer temp adjusting...but will dropping hot wort on it damage it?

 

[Nwcw2001]

When I use my Refractometer, it just takes a drop from the wort to get a reading. That cools pretty quickly on the sample glass. I just drip the sample off my stirring spoon.

 

[EdWort]

Great job as usual Bobby!

 

[Fingers]

Very timely post. I expect my refractometer will arrive this week.

Do you just rinse off the lens between uses? How easy is it to clean?

 

[bob1852]

Question...when drawing a pipette sample for preboil gravity, where it's come out of the mashtun @ around 150ish degrees, how long to you have to let the sample cool before dropping it onto the lens? You mentioned something about the refractometer temp adjusting...but will dropping hot wort on it damage it?

Revvy,

the sample usually cools pretty dang fast -- like the time between extraction and placing 2-3 drops on the lens. Heck, it's a glass lens at room temp, so a couple drops of ~150*F wort won't hurt anything. Just make sure you get an ATC (auto temp control) one, and calibrate it with distilled water the 1st time you use it.

I got mine on eBay (my 1st and only purchase on eBay) for ~$15 on my second auction attempt.

You'll never go back to hydro's (well, except when you rack, you want to taste a sample, you want to compare refract v. hydro, you don't want to convert your Brix once fermentation starts). Heck, like Bobby says, both have their place, but refracto's are definitely worth it for AG brewing to test the runnings...

 

[bob1852]

Do you just rinse off the lens between uses? How easy is it to clean?

I just wipe it clean with a small cloth. You're only using a couple drops so it's really easy.

 

[bob1852]

Great job as usual Bobby!

+1 - thanks Bobby!

 

[Bobby_M]

It was already said, but with such a small sample size, it will temp compensate in about 20 seconds after you drop the sample on the window. It even works that quickly when your kettle is boiling.

I wipe it off with a damp paper towel, then dry.

You can use different ranges but the one that is closest to your typical use will be easiest to read. If you think about it, the distance between 9-10 brix will be half the distance on a 0-70brix scale.

One thing to note is that you can still measure huge gravities on a smaller scale hydro by mixing your sample 1/2 and 1/2 with water. For example 1ml of 60brix wort mixed with 1ml of 0brix water will read 30brix.

 

[olllllo]

[Temperature compensated refractometers] are temperature compensated by means of a bi-metal strip that expands or contracts depending on the temperature of the instrument. This bi-metal strip moves the optics inside the instrument to adjust for temperature variations.

Therefore the temperature of the instrument itself is affects the accuracy of the brix measurement and not the sample temperature (as Bobby_M suggests will rapidly cool). In other words, don't leave it in the sun or out in the freezing weather or it will read funny. Keep it at room temperature and it will be fine.

 

[olllllo]

BTW that was a clarification and not a criticism.

 

[bob1852]

Bobby,

I read somewhere (maybe Palmer - can't remember) that:

OG = Brix/1.04 X 4

obviously G=Brix X 4 is (without the /1.04) pretty close, but a couple points here and there can have some effect on your efficiency calculations, right?

Example:

18 Brix/1.04 x 4 = 69
18 Brix x 4 = 72


anywho - thanks again for all your help with us n00bs, and if I didn't already have a refracto, this video would've further convinced me to get one...

 

[Bobby_M]

That's a good point about the "actual" formula. I suppose I've been choosing math I can do in my head over most accurate. If I wanted to be closer, I'd say multiply brix by four and then just subtract 2 points for anything over 12brix (subtract only 1 point if below 11brix. Good enough for me.

 

[bob1852]

yeah, when I'm taking runnings I convert just by multiplying by 4 to see where I'm at; but in the notes I just record brix and do the full calculation later for efficiency....

good points all around on this thread!

 

[angrysparrow]

Thanks for clarifying all this so completely. This should be a sticky.

 

[aekdbbop]

anyway to do the FG conversion in Beersmith?

btw, what brew is that in the video? Looks delicious!

 

[RiverSwillBeer]

Awesome thread ... Thanks for the video Bobby !!!

+1 for sticky

 

[Bobby_M]

The beer in the vid is a Smoked Robust Porter closely related to the recipe found in Brewing Classic Styles. By far this the best beer I've tasted at only 6 days in the fermenter. I'm a little disappointed in the smoke level though. It's extremely muted. I thought it would be the other way around with 3lbs of smoked malt.

 

[GNBrews]

Thanks for the video Bobby! In the video, you read the refractometer as 9.0% Brix, but later enter 9.5 in the spreadsheet. The graduations on the scale on mine goes in 2's, so you'd either measure 9.4 or 9.6 at the best resolution. What's the deal?

Are you noticing, like I did, that the hydrometer/refractometer values don't really jive even with the compensation calulations after fermentation has begun?

 

[Bobby_M]

Actually I was doing a half assed job of reading the numbers though the camera through the eyepiece. I reread it off camera and it was just over 9.4 so I rounded up.

In the last three batches, I crosschecked hydro/refract and the FG was always within 1 point up or down. The margin of error can be due to a slightly misread OG also but even 2 points would be OK with me.

I'll probably crosscheck one more batch with a lower OG just to be sure but after that I probably won't use the hydro unless I want a taste.

How far off are you experiencing?

 

[lamarguy]

The ATC refractometer I use for measuring SG is based on the standard brewing scale.

The only downside is it's limited to an SG of 1.070 but 98% of the batches I brew are within that range. Also, using a smaller scale, the accuracy is the same as a hydrometer (0.01 instead of 0.02).

Just something to consider unless you're brewing strong ales all of the time.

 

[ArcaneXor]

Well, you convinced me to order a cheap Hong Kong ATC-refractometer as a backup for my hydrometer. I'm curious just how good that spreadsheet turns out to be for FG measurements of various types of beer.

 

[Jaybird]

DAMN YOU BOBBY!!!!!!!!!!!!*****ARG JJ's off to buy a refractometer**** I have been trying to put this off as long as I can remember, and I had so many reasons to justify NOT buying one. But Oh no you come up with the B3 spreadsheet! Damn it!!!!
Cheers
JJ













Great video

 

[DeathBrewer]

that was great. i use a refractometer for pre-boil and pre-ferment but heard that using it for post fermentation was unreliable. thanks for the video. i may have to try a little side-by-side myself.

 

[GNBrews]

Bobby: Right on; I'm glad it's working for you..there's hope yet! The conversion was 6pts low on one batch, and 7pts high on another. I made up some sugar solutions, and they were spot-on with Pro-Mash's refractometer calculator, so I know it's at least useful for pre-ferment measurements.

Deathbrewer: If you do a side-by-side, please keep us updated! I plant to brew tomorrow, and will do the same.

 

[Eskimo Spy]

Bobby, what make and model refractometer are you using? Where did you buy it?

 

[bob1852]

Deathbrewer: If you do a side-by-side, please keep us updated! I plant to brew tomorrow, and will do the same.

I'll do the same during my next brew session and will try to remember to report back...

heck, I'll do it when I rack and bottle my two current brews as well...