$29.90 Ebay Refractometer

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smizak

smizak

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I just bought this refractometer, the one that was linked to in the "do I need a refractometer thread". I think it's from NIS supply.

I made a 5 Brix solution by adding 5g of sugar to 95 grams of water to test it. Calibrated with distilled water and it was dead on. My problem is when I tested it with a 1.049 solution of dissolved DME, to get my refractometer calibration number for Beersmith. I read a Brix number of 11.4, which in every calculator I use is around 1.046. This 3 point difference has got me worried. I triple checked the numbers and even recalibrated, same difference.

What sort of accuracy do you guys get with a refractometer? A three point SG error pretty much makes this thing useless to me.
 
Did you make sure to leave the sample on the sight glass long enough for the ATC to work? How did you measure the 1.049 reference solution?
 
I measured the sample with my hydrometer. I allowed the sample to sit for about 30 seconds. Isn't ATC only for the temperature of the device, so recalibration is not necessary for different ambient temps?
 
I gave up on my refractometer...

For one, when I bought it, I didn't realize that it was useful for un-fermented wort only. Once the yeast eat the sugar it's useless.... and, since it was never quite the same as my hyrdo, I'd rather read my OG and FG with the same device. I found the whole purchase anti-climactic.
 
smizak said:
I measured the sample with my hydrometer. I allowed the sample to sit for about 30 seconds. Isn't ATC only for the temperature of the device, so recalibration is not necessary for different ambient temps?
Click to expand...

It's for both. The thermal mass of the refractometer is extremely high compared to the few tiny drops of sample you drip onto it, but you have to wait ~1min for them both to come to the same temp before you get an accurate reading. I've seen a variance of up to .5% Brix if I don't let the temperature stabilize before reading it. It's also sometimes hard to read if the refracted line is not nice and sharp.

Your hydrometer might be inaccurate too.
 
Did you take the hydrometer sample at the recommended temperature? Have you calibrated it at said temp? Plain water should read 0.0 at the correct temp.

What constant did you use to convert from brix to sg?

HopHead, you can use your refracto for FG, you just need to do the calculations to correct for the alcohol.

B
 
bad coffee said:
Did you take the hydrometer sample at the recommended temperature? Have you calibrated it at said temp? Plain water should read 0.0 at the correct temp.

What constant did you use to convert from brix to sg?

HopHead, you can use your refracto for FG, you just need to do the calculations to correct for the alcohol.

B
Click to expand...

Both instruments were calibrated and read 0 with water. Like I said, it read perfectly accurate with a carefully measured sucrose solution of 5 Brix. My problem is with the DME solution, the measurement was so far off from the hydrometer reading as to make it useless to me. I understand that the refractometer will skew readings because of non-sugar content wort, but the degree and impossibility of knowing these factors from wort A to wort B has me bummed out about buying it. Oh well, more research before I buy a new toy next time.

If I'm wrong about this and there is a better method for correction, please feel free to post and tell me. I love the idea of convenience and speed with these tools. I'll still find a way to use it, even if not for wort gravities.
 
HOP-HEAD said:
I gave up on my refractometer...

For one, when I bought it, I didn't realize that it was useful for un-fermented wort only. Once the yeast eat the sugar it's useless.... and, since it was never quite the same as my hyrdo, I'd rather read my OG and FG with the same device. I found the whole purchase anti-climactic.
Click to expand...

You can use the refractometer for FG too. I believe morebeer has the tool on their site.

smizak said:
Both instruments were calibrated and read 0 with water. Like I said, it read perfectly accurate with a carefully measured sucrose solution of 5 Brix. My problem is with the DME solution, the measurement was so far off from the hydrometer reading as to make it useless to me. I understand that the refractometer will skew readings because of non-sugar content wort, but the degree and impossibility of knowing these factors from wort A to wort B has me bummed out about buying it. Oh well, more research before I buy a new toy next time.

If I'm wrong about this and there is a better method for correction, please feel free to post and tell me. I love the idea of convenience and speed with these tools. I'll still find a way to use it, even if not for wort gravities.
Click to expand...

What was the ambient when you adjusted the refractometer. Even with ATC you have a window for use off the top of my head it 68-86° . So in either case of calibration or reading if you are outside those temps the unit will not work correctly
 
bad coffee said:
Did you take the hydrometer sample at the recommended temperature? Have you calibrated it at said temp? Plain water should read 0.0 at the correct temp.

What constant did you use to convert from brix to sg?

HopHead, you can use your refracto for FG, you just need to do the calculations to correct for the alcohol.

B
Click to expand...

Plain water should not read 0 ... There are solubles in the water that will show up distilled/deionized water will read zero. But if you are using the straight tap water to brew then yes I would set it to zero this way then you remove the solubles from the wort readings that were in the water.
 
samc said:
What does the $4.00 price tag have to do with the accuracy of what is a basic and simple device that has been used for centuries ?
Click to expand...


because they are known to not be 100% accurate . If you bought two from different companies chances are they wouldn't read the same. I have calibrated thermos with certificates that don't read exactly the same.


I read that you calibrated the hydro to zero at what temp did you do this?

Also when you took the two readings where they at the same temp . Reason I ask is hydro's usually are calibrated at 60° and the ATC has to be between 68-86° to ea accurate.
 
I used distilled water. Hydrometer reading for wort and distilled water were both read @ 60F, the temp the hydrometer was calibrated at.

I was very careful when I did these readings. I guess my main question, being a refractometer noob, can I expect a reasonably accurate measurement of wort sugar content? Or are they just a quick ballpark type measuring device?
 
springer said:
Also when you took the two readings where they at the same temp . Reason I ask is hydro's usually are calibrated at 60° and the ATC has to be between 68-86° to ea accurate.
Click to expand...

When you say 68*-86* do you mean the ambient room temp, or the temp of what you are reading? I didn't think temp was an issue.
I picked up the refractometer from Austin Homebrew when they had the sale, and it always seems to be three points off just like the OP's.
I have it calibrated to 0, and checked it 2 more times.
This morning I took gravity samples for my IPA and Hefe, and both were three points different again. I use the morebeer worksheet that Bobby M used in his video. Can it be that?
 
Dave258 said:
When you say 68*-86* do you mean the ambient room temp, or the temp of what you are reading? I didn't think temp was an issue.
I picked up the refractometer from Austin Homebrew when they had the sale, and it always seems to be three points off just like the OP's.
I have it calibrated to 0, and checked it 2 more times.
This morning I took gravity samples for my IPA and Hefe, and both were three points different again. I use the morebeer worksheet that Bobby M used in his video. Can it be that?
Click to expand...

That's what is so aggravating! I sit there and watch BobbyM get dead on results and mine are all over the place. Is the AHB one the RHB-32ATC model? Bobby's looks a little fancier, I wonder if it is the device manufacturer.
 
smizak said:
That's what is so aggravating! I sit there and watch BobbyM get dead on results and mine are all over the place. Is the AHB one the RHB-32ATC model? Bobby's looks a little fancier, I wonder if it is the device manufacturer.
Click to expand...

Yeah, I am pretty sure it is the RHB-32ATC. I see on the direction sheet the temp range of 50*-86*F. But I still think that refrences room Temps, not wort or beer temps.
 
Dave258 said:
Yeah, I am pretty sure it is the RHB-32ATC. I see on the direction sheet the temp range of 50*-86*F. But I still think that refrences room Temps, not wort or beer temps.
Click to expand...

Absolutely, I agree. There is a bi-metal spring that adjusts the lens inside the tube. The tiny little wort sample temp is negligible, unless it's like 800F or something. :D

If I have time tonight, I'll put together solutions of sucrose from 5 to 20 in 5 degrees Brix increments. I'll record the refract number as well as the hydrometer value. Then as best I can do the same measurements using DME. I'll get a base calibration number and see if it's useful over my next couple brews. I don't think it's the device, it read my 5 Brix solution almost perfectly. I just want some real knowledge of what kind of error a malt wort refractometer reading has versus just sucrose.
 
My refractometer states that the ambient room temp and the temp of the unit be 68°-86° and to let the sample adjust by letting it sit on the prizm lens for at least 60 to 90 seconds this way it too will be the same temp, that little bit of wort isnt going to change the units temp. Also all air should be removed from the sample by slight pressure being applied to the clear cover.


Actually I was wrong on the range I have the RHB-32ACT unit and the usfull range is 50-68° but the temp you calibrate it is 68° so if you calibrated it at 60° that may be the problem. Mine is dead nuts on with my hydro but that dont mean the hydro is 100% right . i just take it for what it is.
 
springer said:
My refractometer states that the ambient room temp and the temp of the unit be 68°-86° and to let the sample adjust by letting it sit on the prizm lens for at least 60 to 90 seconds this way it too will be the same temp, that little bit of wort isnt going to change the units temp. Also all air should be removed from the sample by slight pressure being applied to the clear cover
Click to expand...

I also noted a 4 degrees difference in the reading when the cover wasn't totally flush to the prism surface, even with no bubbles present.
 
smizak said:
I also noted a 4 degrees difference in the reading when the cover wasn't totally flush to the prism surface, even with no bubbles present.
Click to expand...

I would think so since you are actually changing the angle at which the light goes through the wort . Kinda making a prizm on top of a prizm. I alway give it a slight bit of pressure to get the air and excess wort out .
 
samc said:
What does the $4.00 price tag have to do with the accuracy of what is a basic and simple device that has been used for centuries ?
Click to expand...

Because the cheaper things get, generally, the less accurate the manufacturing gets.


I can go and grab a dozen $5 thermometers from Walmart, and they're all going to read differently.


My point is, why are you implicitly trusting the hydrometer and not the refractometer?
 
curtis97322 said:
Did you measure the sucrose mixture's gravity with the hydrometer as well?
Click to expand...

I didn't, and should have. I only read the malt solution with the hydrometer and compared it with the refract reading. I'll do this tonight. I really can't rule out that my hydrometer is out of wack. It will read 0 with 60F water, but I can't say it's accurate with any other reading.

springer said:
this may be the problem mine states to calibrate the refractometer @68 and my hydro is 60°
Click to expand...

I calibrated my refractometer upstairs @ ~68-70F. The hydrometer samples I cooled to 60F. Hmmm, I wonder if my thermometer is off too......:eek: :D
 
smizak said:
I calibrated my refractometer upstairs @ ~68-70F. The hydrometer samples I cooled to 60F. Hmmm, I wonder if my thermometer is off too......:eek: :D
Click to expand...

isn't this a wonderful hobby... Next you need a 100$ thermo to check your 4$ hydro and when you brew with someone his 200$ thermo reads different than yours in the same mash....RDWHAHB:mug:
 
Just FYI, NIS still has these for $29 shipped from CA instead of somewhere in China.

search this: NEW! 0-32%ATC Brix Refractometer Wine Beer CNC Softcase
 

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