Hydrometer vs. Refractometer

[mwm5461]

Hello all,

I just wanted to gauge the community's input on this subject. When I began brewing I would always pull samples and then take a hydrometer reading. When I got more into the hobby this past year I was super excited to get a refractometer since I read about how easy it was to take samples and the small amount of liquid required.

During my first brew with the refractometer I also used my hydrometer to check to make sure measurements were accurate. Everything seemed fine after that first brew so I switched to always using a refractometer unless I was measuring FG, in which case I would use a hydrometer.

Over my past couple brews I began to get concerned about the accuracy of my refractometer reading. I typically would take a sample with a tablespoon, cool it with an ice cube, and then drop a sample onto my refractometer (since it's my understanding refractometer readings need to be cooled down to room temp). My last brew was a near perfect day, smooth and hitting all my numbers; I also used both instruments again to ensure accurate readings. My refractometer had a variance of .003 on my post boil gravity so I went with the hydrometer reading.

After this last brew I don't really feel I can trust my refractometer over my hydrometer. Was I doing something wrong in my measurement process? Do others feel this way? Has anyone else had a similar experience? I look forward to hearing input from the community.

Thanks!

 

[jurgenph]

did you calibrate your refractometer?

assuming that you did, and used distilled or RODI water to calibrate it at 0 brix, or 1.000 SG

every tool will have a margin of error, and the further away you are measuring from your calibration point, the bigger your margin of error will be.
i'm not sure how much of a problem this is for hobby grade refractometers. i try not to worry about it

if you trust your hydrometer reading more, you can take your post boil sample, and calibrate your refractometer against your hydrometer reading. and your future measurements should be more in-line with each other.


J.

 

[kh54s10]

The hydrometer sample, the couple of drops on the lens, will cool in a matter of seconds. There is really no need to do any other cooling.

Are you calibrating the refractometer every time. I check it with tap water, distilled would be better, before every reading. It should read 1.000, if it doesn't there is a little screw in the top of the tube. Adjust until it reads 1.000 then dry off the lens and the cover then read your sample.

 

[Galactik]

The hydrometer sample, the couple of drops on the lens, will cool in a matter of seconds. There is really no need to do any other cooling.

Are you calibrating the refractometer every time. I check it with tap water, distilled would be better, before every reading. It should read 1.000, if it doesn't there is a little screw in the top of the tube. Adjust until it reads 1.000 then dry off the lens and the cover then read your sample.

This. I check every brew day and I find 70-80% of the time it needs an adjustment, mainly just a small one.

 

[RTL]

Read these links, and if it hasn't been said enough calibrate it every time! This is very important because they are very susceptible to shock/vibration (especially the cheap ones we use). I don't even set mine down after I cal it, just wipe it off and take the sample immediately. Download the spreadsheet from brewers friend and start filling it in on every brew, you will gain much greater confidence in your refractometer.

http://www.brewersfriend.com/2013/0...rrectly-for-maximum-accuracy-in-home-brewing/

http://www.brewersfriend.com/refractometer-calculator/

 

[bucfan1234]

I switched to the refractometer, and haven't looked back. The ease of use sealed the deal.

If I am three thousands off I'll never know it.

 

[Ike]

I switched to the refractometer, and haven't looked back. The ease of use sealed the deal.

If I am three thousands off I'll never know it.

Pretty much this, although I'm still getting mine dialed in. Using

http://seanterrill.com/2012/01/06/refractometer-calculator/

and the default 1.04 correction factor, my numbers are close but not ideal. I'm currently collecting my own data to calculate the factor specific to my refractometer.

So for the moment I'm doing both, but soon hope to move to using the refractometer for any "in process" measurements, i.e. anything that isn't OG or FG.