Refractometer

[Jsbeckton]

Bought a $45 refractometer that measures in both SG and Brix.

http://www.amazon.com/dp/B006GG0TDK/ref=pe_175190_21431760_M3T1_SC_dp_1

Calibrated it with distilled water and did some tests. My accurate hydrometer read 1.047 (temp adjusted) and the refractometer read 1.042-1.045 over 4 readings. So my questions are is it normal to get this range over a few tests due to the small sample size a refractometer uses and is the error enough to suspect that I got a faulty refractometer or is this as close as I am going to get in this price range?

The discrepency seemed to vary a bit around the different gravaties I tested but generally the refractometer read lower than the hydrometer and not by the same 3 points as described above, seems to be more accurate at lower gravaties and less accurate at higher gravaties.

Would appreciate feedback from others who use a refractometer. Is so great to get a instant gravity during mash and boil without having to cool so I want to make sure that I don't just have a lemon.

 

[day_trippr]

Were you reading the gravity using the refractometer SG scale, or did you take the Brix reading and use any of the free on-line conversion programs (like this one) to convert to SG?

My refract was sold with a very common defect with the SG scale: it simply is not accurate, and the problem doesn't require actually measuring anything to detect: pick a random high Brix value (like anything over 15) and check what the refract shows as the equivalent SG, then plug your chosen Brix value into one of the conversion programs and compare the result with the refract SG.

Anyway...if I use the Brix reading on my refract, I consistently get a value that matches my hydrometer within a point (ie: .01 SG). And that includes post-fermentation readings - though obviously that means using a valid recorded OG to use in deriving a valid post-fermentation value from the refractometer.

At the end of the day, I explicitly trust my hydrometer over my refractometer, but only because I've used the former for a decade and it has never left me scratching my head, while I only got the latter last year and haven't built up the experience level to the same point...

Cheers!

 

[Jsbeckton]

It has both Brix and SG (dual scale), so .01 is the closest you can get? That doesn't seem worthwhile if that is all you can get.

 

[Jsbeckton]

I will check the Brix scale when I get home to see if that shows a discrepancy between scales. Seems like that is a easy flaw for a manufacturer to fix. It had a bunch of positive reviews and nobody mentioned that about the SG scale being inaccurate.

 

[jtejedor]

Honestly I have just been using my refractometer as a guideline. I keep going back to my hydrometer for a completely accurate reading. I also got a finishing hydrometer and I love it. Granted my refractometer is a cheaper one off Ebay but I remember people on the forumn recommending them. Not sure about water but even though my refractometer says it has atc I find the readings to be way more accurate when I let the sample sit.for a while and cool down to as close to 60 degrees as possible.

 

[Calder]

I've got nothing to add to this thread.

But .....

I consistently get a value that matches my hydrometer within a point (ie: .01 SG).

If that is the best you can do, it ain't worth it. I can guess closer than that.

I assume you mean .001.

 

[day_trippr]

I've got nothing to add to this thread.
But .....

If that is the best you can do, it ain't worth it. I can guess closer than that.

I assume you mean .001.

Whoops! Yes, of course, .001. Fat fingered that one and didn't even notice it

Cheers!

 

[Jsbeckton]

I checked the scale today, at 26 Brix it shows 1.100 as the equivalent SG. Beersmith says that it should be 1.108 so there is a 0.008 point difference!

Is this a common problem with all SG scales? Seems like it would be so easy for the manufacturer to correct.

 

[jheld00]

I got the same refractometer about a week and a half ago, used it last Sunday. It was dead on after calibration. This is my second refractometer(broke the first one) I have found that the ATC isn't very reliable. While I'm brewing I keep a glass of ice water handy and dunk my pipette in it for 30secs or so to cool down the sample. Also personally during and post fermentation I always use my hydrometer, even with the calculators online and elsewhere I find the hydrometer to be most accurate. If your refractometer is truly off that much I would contact the seller about a replacement.