• Welcome to the new forum! We upgraded our forum software with a host of new boards, capabilities and features. It is also more secure.
    Jump in and join the conversation! You can learn more about the upgrade and new features here.

Temp. Compensating Refractometer?

Pyrexic

Apprentice
Joined
Dec 29, 2023
Messages
25
Reaction score
10
Lately I have been missing my numbers on brew day and attributed it to me getting back into brewing after a 23 year break. One difference I made given the advances in equipment available to the homebrewer is that I started using a refractometer during the mash and to get my OGs. I didn't get the cheapest one and was highly rated and had temperature compensation. When received, I calibrated it with distilled water and a 1.040 sugar-water standard. The unit was spot on out of the box and I check zero with water every brew day. Previous beers were bigger IPAs so even though I didn't hit my numbers per the recipe (according to the refractometer) I never made any adjustments and they all still came out great.

Yesterday, I brewed a summer ale that was targeted to be an OG of 1.047-053. After mashing, no starch signature with an iodine test, yet my first runnings were just at 1.055 (when converted from Brix). Again a little disappointed as I knew that would dilute down about 10-15 points. This brew I did 2 changes: I was about 10 points off on my pre-boil starting gravity, so I added some Extra Light DME and the second change was that I just got a Rapt Pill hydrometer for the fermenter. I am not looking for the Pill to provide accurate hydrometer readings, just a better indication of where I am in the fermentation stage for dry hopping, kegging, conditioning etc. But I did also check and calibrate the Pill as well and after calibration was pretty accurate in non-fermenting sugar water. (+/- 0.002 SG).

Sorry for the long lead in, but pitched my yeast, took an OG with my refractometer and got 13.0 Brix (1.052 sg) which is spot on with the addition of the DME, put in the Pill and closed it up. The Pill OG is reading 1.066 sg @ 68 F which is what I have the fermentation chamber set at. I can't believe the Pill is that far off and started doing some additional research. When the refractometer states "temperature compensating" is that for the temperature of the refractometer (i.e., ambient temp) or temperature of the wort? I just didnt think that a thin film of liquid would be any other temperature than ambient, but it appears that the readings are very temperature sensitive. In looking at adjustments, if the wort was at 145 F when read, that would account for the difference. I could see this when checking my mash or runnings but not sure what the deal is when checking my OG when the wort is cooled and in the fermenter at ~75 F.

However, I seemed to be missing my numbers consistently by 10-13 points but looking at this, I could have been spot on. I really like the convenience of the refractometer and the fact it doesnt waste a lot of wort at the start. I still use a hydrometer to determine the FG but use that as an opportunity for a tasting too. Anyone else have this issue? Not spending the money on an EasyDens system but are there other options? Or is there a refractometer you recommend if mine is crap?
 
If you are consistently missing your gravities the fault may lie in your equipment profile. Have you customized your profile or simply picked on off of the equipment list and ran with it?
 
The temperature compensation is for the temperature of the refractometer. The wort will rapidly get to the temperature of the refractometer, and unless you repeatedly put hot wort onto it the refractometer will stay at the temperature of the room it is in. I recommend you use both a refractometer and a hydrometer at various stages of your next brew and compare them to see where the problem may lie. Be sure to stir your wort before taking a sample to eliminate stratification. If used properly a refractometer should give good readings.

--GF
 
Both are good suggestions and I plan on seeing where the problem lies. I did tweak an equipment profile, but I didn't go and measure dead volumes, heat losses, etc. Before I put everything away, I will gather more equipment information and update my profile. Do you know if anyone has a more rigorous boil off calculator? I live in Texas where temps can be from freezing to 110 F and 30-90+ % humidity. I would think there would be a spreadsheet where we could enter in pot diameter, elevation, %RH, and ambient temp and get a pretty accurate vapor pressure calc for boil off and could be used by anyone anywhere.

I used to do everything with hydrometer only 20+ years ago. Guess I got caught up in the new tech and need to go back and double check with my hydrometer. At least pre-boil, I can put it back so not any real volume losses there. The next one should be interesting and will report back the results.

Has anyone used the narrow band hydrometers (comes in a set) vs the standard 0.99-1.17 which is what I have (30+ years old) and I have checked in water and sugar solution when checking the refractometer and Pill. So if it is off, at least they should all match :) Just wondering if they provide any better results/resolution or use less liquid per reading?

Thanks
 
This is a great tutorial for creating an equipment profile.
 
Back
Top