Refractometer Calibration

[Beer-Baron]

Hi,

I just got a new refractometer. The instructions say to calibrate it using distilled water.

Is this ideal considering I use my tap water for brewing?
Should I be calibrating with my tap water instead?

What do you think?

Thank you

 

[nilo]

Use distilled water. You can buy that on your local grocery store. 1gal will last years
You should calibrate with distilled water before every reading. If you are taking multiple readings in a row or spaced by few minutes and in the same environment (same ambient temp), no need to recalibrate.

 

[joeunc]

I thought once it was calibrated the first time correctly you were good. Most refractometers auto adjust based on the temp of the liquid you test.
I would think you may need to recalibrate with a drop of distilled water again if you go a long time between brewing sessions.

Use distilled water. You can buy that on your local grocery store. 1gal will last years
You should calibrate with distilled water before every reading. If you are taking multiple readings in a row or spaced by few minutes and in the same environment (same ambient temp), no need to recalibrate.

 

[Beer-Baron]

Use distilled water. You can buy that on your local grocery store. 1gal will last years
You should calibrate with distilled water before every reading. If you are taking multiple readings in a row or spaced by few minutes and in the same environment (same ambient temp), no need to recalibrate.

I don't think I need to actually buy distilled water. I figure I can just boil some water on the stove, and then take the cold lid of the pot and hold it over top of the steam until it turns back into water and collect a few drops from that.

 

[Beer-Baron]

I thought once it was calibrated the first time correctly you were good. Most refractometers auto adjust based on the temp of the liquid you test.
I would think you may need to recalibrate with a drop of distilled water again if you go a long time between brewing sessions.

That makes sense to me. I just figure you need a couple drops of what you are testing and then you close up the lense and leave it for about 1 minute. In that time the wort would have cooled down to the temperature of the refractometer and be ready for a reading.

No?

 

[joeunc]

you should be able to get instant readings, that's what the refractometer is good for, It auto adjusts for temp of the liquid so you don't have to wait too long.

 

[nilo]

The calibration you do is not for the temp of the sample but for the temp of the device, that's what I understand. Calibrate it on a 60F room, then move to a 70F room and wait 10min, add a drop of distilled water and look it again. It will be off and a new adjust is required.
I'm using one for a while, stated ATC by the vendor, and that's how it works for me.
If you can produce distilled water yourself, fine. 1 Gal at store cost probably 2 bucks.

 

[Beer-Baron]

Well I just tried it out. I took a sample of my beer. I just recalibrated the refractometer with distilled water. I took a reading of my wort. 1.050. Then I put it in the hydrometer and I've got 1.042. One of these things is WAY off and I think its the refractometer.

Any suggestions?

 

[Nugent]

Two things.

First, from what I understand, the refractometer is only truly accurate when the unit and the sample are both at 20c. When you put a millimetre of liquid under the lens cover it cools in seconds. So room temp and sample temp are both important. Room temp more so in this case.

Keep in mind, though, that refractometers are only so accurate. There is a reasonable +/- error on all instruments. Plus, unless you bought a hyperaccurate refractometer that cost hundreds of dollars, there will be some error. Finally ... how did you calculate the Brix to SG? It's not exactly 4 to 1. There are on-line correction calculators for this.

Second, what was the temp of the wort? Did you adjust for temperature with the hydrometer reading?

 

[Beer-Baron]

Well my refractometer actually has a secondary scale beside the BRIX in gravity for beer/wine.

I was testing some Skeeter Pee (www.skeeterpee.com) and its about half way through fermentation. the thermomter on the outside of the better bottle says 72 degrees. No I didn't adjust for temperature with the hydrometer. I guess I don't know what I'm doing

 

[xenocide]

From my understanding, you must correct for the alcohol once fermentation begins.

 

[Beer-Baron]

From my understanding, you must correct for the alcohol once fermentation begins.

Well I did. My OG gravity was 1.076 by hydrometer. today its 1.042 by hydrometer

 

[Nugent]

From my understanding, you must correct for the alcohol once fermentation begins.

What this poster meant was that your refractometer will give a false reading once fermentation has begun, as the alcohol will mess it up.

Try this: http://www.onebeer.net/refractometer.shtml. It will allow you to see what your corrected gravity is.

If you're feeling that you "don't know what you're doing", here's a good place to start: http://www.howtobrew.com/. I'd buy the actual book version, though; IMO, it's the best homebrewing reference book out there.

 

[Shooter]

Unless your tap water is really hard you can calibrate with it, depends on your water. I used to use distilled water, until I heard a few people mention that. So, I did a test and calibrated it with distilled water and then tested it with tap water. The reading was identical or, so close to identical, that I was not able to see the minor difference between tap and distilled.

 

[joeunc]

MoreBeer has a tool that allows you to use the refractometer throughout the process.
It already does the alcohol correction for you, You can download it here:
http://morebeer.com/learn_vids/vids_refract