Large difference between refractometer & hydrometer

[HanksHill]

Anyone ever seen this before - I have both a digital refractometer (Milwaukee Instruments) and a analog. My hydrometer broke so figured I'd rely on those to determine when the Brix reached zero. I thought I had a stuck fermentation on both my Cab Sauv and Cab Franc at about 7.5 Brix. Seemed like too big of a coincidence, especially after adding more yeast and nothing additional happening. Borrowed a Hydrometer from a friend and sure enough both were dry. Pressed them out and they're in the tanks now. Are refractometers not useful below a certain point?

 

[balatonwine]

Refractometers are only accurate on sugar solutions. Once things start to ferment, you can not use them directly. You then have to apply a correction factor.

 

[HanksHill]

Refractometers are only accurate on sugar solutions. Once things start to ferment, you can not use them directly. You then have to apply a correction factor.

Noted - new hydrometer is on its way. Luckily I didn't let it sit too long after fermentation stopped.

 

[Jim Welch]

Anyone ever seen this before - I have both a digital refractometer (Milwaukee Instruments) and a analog. My hydrometer broke so figured I'd rely on those to determine when the Brix reached zero. I thought I had a stuck fermentation on both my Cab Sauv and Cab Franc at about 7.5 Brix. Seemed like too big of a coincidence, especially after adding more yeast and nothing additional happening. Borrowed a Hydrometer from a friend and sure enough both were dry. Pressed them out and they're in the tanks now. Are refractometers not useful below a certain point?

They are accurate provided one applies the correction as balatonwine mentioned. I find a refractometer much faster and easier to use during fermentation by just letting 4 or so drops of must fall onto it after I’ve stirred/punched down since I do multiple batches at the same time.
There are online correction calculators, I’ve downloaded an Excel file from more wine and when I start my batches and have a stable OG to use it to calculate several data points: 1/3 sugar break: 1/2 sugar break; 10% ABV; 1.010 SG; and 1.000 SG
With these I know when to add nutrients, when not to, and when to transfer out of my buckets into secondary. I do use my hydrometers before pitching and when I transfer, saving that sample for preliminary ph, SO2, TA and/or residual sugar testing as well as a tasting sample.
One thing I have noticed is when there is little or no alcohol there is a crisp delineation on the scale. As alcohol increases the border gets “fuzzy”, losing that crispness.

 

[salcoco]

used a refractometer thru fermentation for over 20 years with correction table works great. there is an argument that at low values near finish it may be inaccurate even though corrected. just use a hydrometer at this point if necessary.

 

[mainshipfred]

I agree with @salcoco with regard to the refractometer and as long as you're just making sure the wine is still fermenting the correction factor is not really necessary. I do normally use the hydrometer though and definitely when it's getting close to finished.

 

[StimVino]

I bought the hanna brix refractometer hoping this would simplify my work during fermentation and never regretted more buying such a piece of junk. Totally inaccurate below 6 brix. (In fairness, I have not explored the correction factors mentioned above. I guess I feel like for $200 it should have the correction factor built-in.) However, now I added sampling spigots to all my fermentation Vessels so that I can easily do a hydrometer readings and pour the liquid back into the fermenter after sampling. Way more accurate.

 

[CDrew]

What really matters, is the finish. You need to know you are not stuck. I can highly recommend a finish hydrometer that is -5/+5 brix. Then you know. Refractometers are only useful at harvest to get starting brix.

You really need this

 

[balatonwine]

I bought the hanna brix refractometer hoping this would simplify my work during fermentation and never regretted more buying such a piece of junk. Totally inaccurate below 6 brix. (In fairness, I have not explored the correction factors mentioned above. I guess I feel like for $200 it should have the correction factor built-in.)

Refractometers with built in correction are super laboratory grade and would be much more expensive than $200 (if they exist ?).

Before buying tools is best to understand their fitness for purpose and cost benefit ratio. So often I sadly see critique of a tool is often from ignorance about the designed (i.e. built in) limits of the tool. Such comments miss the relevant fit for purpose intended use of the tool. Which is rather unfair (i.e. claiming a Lamborghini is a piece of junk because it bottomed out during the Shara Rally and for its price the car should have come with a lift kit and large tires says more about the person making that comment than about the car....).

First to consider: a basic refractometer is actually not really a precision instrument. It gets one close enough to start. But other tools should be used later to get better accuracy. I bought mine (hand held) in Switzerland. A great tool. Cost me about 70 CHF. It is great for what I use it for. Had it for almost 20 years. Still doing its job. And the job mostly is to get field based values in the vineyard. That is I have it in my hand, pick a few grapes here and there, and test Brix. When things get close to harvest levels, I may select clusters, crush them and test them with the refractometer and pH meter to test ripeness. As things get really close, I use a hydrometer. Which is more accurate. And use the hydrometer there after.... well mostly, I sometimes sample, use the refractometer (apply correction) to get a "guesstimate" of where things are, but for serious work after fermentation started, the hydrometer is really the better tool.

Hope this helps.

 

[winemaker81]

Before buying tools is best to understand their fitness for purpose and cost benefit ratio.

Thanks for the detailed explanation.

Your comment made me think of the electric percolator I purchased a few years back. The reviews were horrible and I was going to pass on it, until I read a review in the same vein as your comment. This review stated that correct grind must be used, and the correct amount of coffee for the amount of water must be used. Too coarse a grind, the coffee is weak, too fine a grind, it's excessively bitter. Similar for the amount of coffee used.

I've been using mine for 5 years -- first couple of pots weren't great, but once I got the grind and ratio figured out, it's been an excellent unit.

 

[StimVino]

I have a refractometer with a lens and a flip top and understand its limitations. Bought it for $16 on Amazon. The device I was referring to was advertised to be 0.2% accurate within a range of 0 to 50 brix. Maybe I am ignorant about its intended purpose. But I dont mind sharing my missteps so that others can better allocate their resources. The link to the device is: Digital Refractometer for Brix & Potential Alcohol - HI96813 | Hanna Instruments I'd be curious if anyone has successfully used the correction factors with this device.

 

[Raptor99]

I use this one: https://www.amazon.com/gp/product/B01M1GLSSF Nothing fancy, but it does its job. When I have measured SG with both my hydrometer and refractometer, the results have come out very close. I think that with careful reading, you can gain an additional decimal place using a hydrometer. But for most of my uses, the refractometer is accurate enough.

Refractometers with built in correction are super laboratory grade and would be much more expensive than $200 (if they exist ?).

It is difficult to see how this would even work. A refractometer correctly measures the refraction index and displays the results on a Brix scale. Once fermentation has started, you need know the original Brix to calculate the SG. The only way that I could see for this to work would be if the high end refractometer had a way to enter the original Brix number so that it could calculate the SG.

I use a calculator such as this one Homebrew Refractometer Calculator to find the current SG. I find that much easier and more accurate than using a correction factor or table. The actual calculation is fairly complex, so any "correction factor" you simply multiply by the Brix reading is only a rough approximation. I think that the calculator is much more accurate. If you really want to do the calculation yourself, there is a formula here: Convert Brix To SG And More - BrÜcrafter

Most refractometers also have an SG scale. I would advise you to always ignore that and record the Brix value. It is misleading to think that you are directly measuring SG.

It is important to understand how the tool works and to how to use it correctly.

 

[Mac60]

I have always used a refractometer at the start to get my Brix measurements, once fermentation started I have always used a hydrometer and put the refractometer away, however this year I used both through the entire fermentation process, and like you mentioned the measurements were close enough to let me know where I was at in the process. Going forward I will be using the refractometer to monitor fermentation progress. Once I get going I have only to watch for my target Brix when I'm close I make a final test with the Hydrometer. For me, Its just cleaner and easier.

 

[winemaker81]

Going forward I will be using the refractometer to monitor fermentation progress.

Although I'm firmly in the hydrometer camp, this makes sense. I'm considering buying a refractometer for ease of use.

As both @balatonwine and @Mac60 have stated -- ya gotta know how the tool actually works. During fermentation I use the hydrometer as a barometer, just to gauge roughly where the wine is in the process. It makes absolutely no difference if the SG is 1.050 or 1.060, as I know the wine is about 1/3 of the way through. As long as I know what the refractometer reading means, it will do what I need. I need exact readings only at the beginning and end of fermentation.

I'm also considering a finishing hydrometer, as @CDrew recommends. It making sense, more and more.

 

[Mac60]

Although I'm firmly in the hydrometer camp, this makes sense. I'm considering buying a refractometer for ease of use.

As both @balatonwine and @Mac60 have stated -- ya gotta know how the tool actually works. During fermentation I use the hydrometer as a barometer, just to gauge roughly where the wine is in the process. It makes absolutely no difference if the SG is 1.050 or 1.060, as I know the wine is about 1/3 of the way through. As long as I know what the refractometer reading means, it will do what I need. I need exact readings only at the beginning and end of fermentation.

I'm also considering a finishing hydrometer, as @CDrew recommends. It making sense, more and more.

"I need exact readings only at the beginning and end of fermentation." EXACTLY....
"I'm also considering a finishing hydrometer, as @CDrew recommends. It making sense, more and more." Agree...
I did just buy a complete lab setup for my SC300 Just can't help myself, And.. another 330 Liter VC tank on the way. Every time we get a new tank will fill it and then need another tank to rack into.. IT never ENDS....

 

[mainshipfred]

Although I'm firmly in the hydrometer camp, this makes sense. I'm considering buying a refractometer for ease of use.

As both @balatonwine and @Mac60 have stated -- ya gotta know how the tool actually works. During fermentation I use the hydrometer as a barometer, just to gauge roughly where the wine is in the process. It makes absolutely no difference if the SG is 1.050 or 1.060, as I know the wine is about 1/3 of the way through. As long as I know what the refractometer reading means, it will do what I need. I need exact readings only at the beginning and end of fermentation.

I'm also considering a finishing hydrometer, as @CDrew recommends. It making sense, more and more.

Glass finish hydrometers are very fragile as the necks are super thin. I broke 2 just by looking at them wrong. The one I have now is a Herculometer and I've had it for 4 years now. It's polycarbonate and accurate enough for me.

 

[winemaker81]

Glass finish hydrometers are very fragile as the necks are super thin. I broke 2 just by looking at them wrong. The one I have now is a Herculometer and I've had it for 4 years now. It's polycarbonate and accurate enough for me.

Good to know. Thanks!

If it's more accurate than a typical hydrometer, it's fine.

 

[mainshipfred]

Good to know. Thanks!

If it's more accurate than a typical hydrometer, it's fine.

I think the range is 1.020 to .990 so even if it's off it's way more accurate than a triple scale.

 

[Jim Welch]

I think the range is 1.020 to .990 so even if it's off it's way more accurate than a triple scale.

I have the same one Fred, it’s 1.020-0.980. Calibrated in distilled water, it is 0.003 low but once one knows the offset it’s simple to correct.

 

[David Violante]

Although I'm firmly in the hydrometer camp, this makes sense. I'm considering buying a refractometer for ease of use.

Bryan, check your drawer of stuff before you buy one, you may already have one!! I’ve seen some of your posts of collection items… LOL