PSA: Calibrate your refractometer

So I brewed a pale ale this week. I've used this recipe about four times. Got the same efficiency every time.

I calibrated my refractometer after the last brew session, and assumed that it would still be calibrated two weeks later. I took a refractometer reading after my first runnings, and it was a little low. I took another reading preboil and I was 6 points low. I took another reading. Same thing.

I accepted my fate and measured out some DME before I started the boil. Threw in the DME and followed the recipe through the boil.

I finished cooling and took a hydrometer sample.

It was 6 points high.

I grabbed some distilled water and sure enough, the refractometer was blue almost all the way to the bottom of the viewer.

I will be calibrating my refractometer before every brew day from now on. And every time that I am getting an unexpected reading.

Eric

I just assumed it was common practice to do this. It takes about 10 extra seconds. Of course I do this and neglect other things on my brew day, like making sure my valve is closed before I add water to my mash tun.

suprchunk said:

I just assumed it was common practice to do this. It takes about 10 extra seconds. Of course I do this and neglect other things on my brew day, like making sure my valve is closed before I add water to my mash tun.

Click to expand...

You are correct, it should be common practice.

Just sharing a mistake so that others don't make the same one.

Eric

That's weird. I calibrate mine every month or so and it is never off by more than a tenth of a degree brix, not any wider than the thickness of the lines on the scale.

To be off 12 points or 3 brix I would think your refractometer is of different manufacture than mine or somebody has been playing with the knob.

Now you can never calibrate your instruments too much, I'm not saying that, but I am surprised to here that your refractometer got that far off that fast.

Each time I have recaled mine it was damn close to zero. Makes me want to check it right now since it's sitting 3 feet from me.

remilard said:

That's weird. I calibrate mine every month or so and it is never off by more than a tenth of a degree brix, not any wider than the thickness of the lines on the scale.

To be off 12 points or 3 brix I would think your refractometer is of different manufacture than mine or somebody has been playing with the knob.

Now you can never calibrate your instruments too much, I'm not saying that, but I am surprised to here that your refractometer got that far off that fast.

Click to expand...

Trust me, no one was more surprised than me. I have checked it again since then and it was still at zero. Maybe it was just a fluke thing.

Eric

I calibrated mine when I got it, but it didn't need calibration. I checked the calibration a few times over the next year, but it never was off. Once every 6 months or so, I check the reading against a hydrometer reading. They have always matched.
There is one possibility for your problems that I can think of. Was the refractometer at room temperature when you checked? If not, the ATC could screw up the reading.

-a.

I checked my refractometer when I used it for the first time and it was dead on. I now check it about once or twice a year and it has never required adjustment. I would think that they should hold calibration pretty well unless maybe it were dropped or was otherwise subjected to substantial shock. They are simple instruments and AFAIK, probably have only one moving part, that being the bi-metal spring mounted prism thingy. Not a whole lot to go wrong.

Just sharing a mistake so that others don't make the same one.

Click to expand...

Thanks a reminder is always good. I think outside temp changes can make a difference, I calibrated inside the house(70deg.) then checked it in the garage on brew day (55 deg) yep it was off. Also I have learned to wait at least 30 seconds after putting sample on it to let the temp adj. to the refractometer.

+1 I think this is a good idea to do regularly. I keep a gallon of distilled water around and check it each brew day. It is typically at zero, but sometimes its a little off.

bbone66 said:

Thanks a reminder is always good. I think outside temp changes can make a difference, I calibrated inside the house(70deg.) then checked it in the garage on brew day (55 deg) yep it was off. Also I have learned to wait at least 30 seconds after putting sample on it to let the temp adj. to the refractometer.

Click to expand...

For this reason, my new procedure will be to have the distilled water out on the porch with the rest of my brewday supplies. I will calibrate the refractometer just before I start to take readings.

Eric

bbone66 said:

Also I have learned to wait at least 30 seconds after putting sample on it to let the temp adj. to the refractometer.

Click to expand...

Yes. Must do this. I add a drop and set it aside. Although mine is ATC, that is for the body of the instrument, not the wort. I need to wait for the drops of wort to come to the instruments temperature.

ya, +1 i usually just use the same water i brew with... i did a comparison and its the same as far as i can tell to using distilled.

I just got one (after breaking my third hydrometer). The instructions say to recalibrate if the environment(not the sample) changes by more than 5 degrees F.

If you always are in a conditioned room, then maybe you don't need to do it as often.

Rich

Cheers! for 6 more points and wee bit more buzz! lol

passedpawn said:

Yes. Must do this. I add a drop and set it aside. Although mine is ATC, that is for the body of the instrument, not the wort. I need to wait for the drops of wort to come to the instruments temperature.

Click to expand...

I have started to do this as well and the readings have been consistent with the hydrometer readings.

Just to update, I continue to check my hydrometer at the start of brewday but have not had any further issues. I have not had to adjust the refractometer again.

Eric

I recently got an AO Scientific model 10440 that displays on the arbitrary scale. I also have a tripple scal hydrometer and could borrow my borther's AO Sci model 10430 (0-30, Brix scale) and I'll run both thru the calibration also.

I plan to calibrate by preparing a series of sugar solutions up to ~ 12% by weight. Brix is based on % sucrose in water. Has anyone given this any thought: Since there is a difference between sucrose (sugar) and grain sugars, would it be better to use DME or sugar when I make up the solutions?

What's the general consensus?