calibrate refractometer, advice

[wlockwood]

I need to calibrate my ebay refractometer. It's a nice one from Fisher Scientific made in Japan.

I'm thinking that if I take 10g table sugar in a graduated cylinder and top it off to 100ml I should then have a 10 % solution.
Does anyone out there have any advice on this?

Also, I don't think my device is auto temp. adjusting but I think the one or two drops I use cool of pretty fast, again any advice?

thank you, will l.

[Blktre]

Nope..no sugar. A drop of water (distilled, but doesn't have to be) and turn the calibration knob to zero. This works because there is no sugar in solution, therefore gravity (brix in this case) is zero.

The ATC versions only read between 68-86ºF with correction. The sample should be between this range. So, as you mentioned, a single drop of wort will cool extremely rapidly. The biggest problem for ATC refracto's is using them when its actually cold outside where the sample is well below 68*F. In your case, I wouldn't worry about ATC either. As long as your sample temps are in this range, your good to go.

[wlockwood]

Great idea, thank you.
I forgot to mention that I was also having doubts about my 10 year old hydrometer. Then just the other day I managed to break it. So now I'm in the market for one, but it looks like a person serious about measurements should really have two different hydrometers. What say you?

[DJ in KC]

Nope..no sugar. A drop of water (distilled, but doesn't have to be) and turn the calibration knob to zero. This works because there is no sugar in solution, therefore gravity (brix in this case) is zero.

The ATC versions only read between 68-86ºF with correction. The sample should be between this range. So, as you mentioned, a single drop of wort will cool extremely rapidly. The biggest problem for ATC refracto's is using them when its actually cold outside where the sample is well below 68*F. In your case, I wouldn't worry about ATC either. As long as your sample temps are in this range, your good to go.

Make certain your refractometer itself is at proper temps. May need to leave it inside if you brew outside in the winter/summer. Took me a while to learn that........ duh

[Jensen]

Make certain your refractometer itself is at proper temps. May need to leave it inside if you brew outside in the winter/summer. Took me a while to learn that........ duh

Took a few times on this end to figure out as well. Best to almost always leave the refract inside till you need it! It will sure read more true. Also when you get your new hydrometer you will want to fill the jar with distilled water and cool to 60 deg (what your hydro will be calibrated at-- or adjust to what it says on the rolled paper inside). It should read dead on zero with distilled water at the calibrated temperature. If not, make a note of how high or low it reads, and post somewhere in your brew area for easy reference. Out of my four hydrometers only one reads spot on without adjustments.-- however they all are equally accurate.