Effects of wort temperature when generating refractometer adjustment??

Hi all,

Recently I purchased a refractometer to use in my brewing/wine making/mead making endeavors. But I'm having a problem getting my mind wrapped around the steps to calibrate the BeerSmith software.

I got a reading of 1.036 @ 69.5F. When I enter that into the temperature correction tool it tells me it is adjusted to 1.037. When I enter in the hydrometer reading from the wort, do I enter 1.036 or 1.037? Additionally, the refractometer I has has ATC built in. Does that convert for the ambient AIR temperature, or does that correct for the wort temperature? I got 10.4 Brix reading on the refractometer.

Obviously, we're talking a thousandth of a point here or there, so in the scheme of things it probably doesn't matter. However, I'd just like to know if I'm doing it right, or not. In a previous forum thread there was a mention by BeerSmith that they were going to put together a video on refractometer usage. Was that ever posted?

Thanks!

Robert

My understanding:

Whatever the "conversion" (not corrected) from brix to SG is .... use that. There is no further correction necessary for temp if your is a ATC model (as is mine).

Having said that, make sure you get a brix reading with pure distilled water, it should be 0. If you get something diffferent you will have to make some correction.

I occasionally will take a sample and test with the hydrometer to back up the converted value, usually too close to worry about any differences.

The ATC on the Refractometer corrects to the temp of the fame of the unit, not the wort on the lens.

As 88Q advised, get some distilled water and calibrate your new refractometer to 0.  Once you know you are calibrated, you can cool the wort to room temperature then measure it on the refractometer.  Use the room temp as the temp adjustment value.

I take a small sample with my stirring spoon and set on the counter to cool a couple minutes.  Sometime I sample from the spoon into my pipette and let it cool in that.  I place some on the lens and take a reading.  Wait a couple minutes and take another.  Sometimes the wort had not cooled enough and the second reading is different than the first.

The calibration tool under Refractometer Tool / Calibrate Refractometer Settings wants you to calibrate with distilled water, measure wort (preferably at 59c so no adjustment for temp is necessary) and measure the wort with a hydrometer.  the tool will determine the different between the two readings and set and adjustment value for refractometer readings you enter.

This is not necessary of you calibrate the refractometer.  Unless you have highly accurate hydrometers and refractometers, you are estimating the final point or two anyway.

I used both tools for a while but now use the refractometer until I take a final gravity reading before transferring to the fermenter.  Then I use both (because I get to sample the wort from the hydrometer tube).  They are always really close. 

-jomebrew

Thanks! I had actually already did the distilled water calibration. Just didn't mention it in the first post.

Robert

I did recently do a post on using a refractometer - its on the blog at http:/beersmith.com/blog

Brad