Refractometer issue?

[MrBarrySir]

Hi all,

I've recently started using a refractometer, today when my wort was almost finished fermenting I took a sample and the refractometer gave me a reading of 1.023. (the refractometer has brix on one side, and specific gravity on the other) I double checked the same sample with a hydrometer and it was giving a reading of 1.011. This was the same sample at the same temperature.

When I initially got the refractometer I calibrated it with bottled water. Does anybody know what is causing this issue?

 

[EVVO]

A problem I noticed before I found out that the final figure needs adjusting because of the alcohol content. There is info on line along with the adjustments reqd. Now I use the refractometer for og and hydrometer for fg.

 

[EVVO]

Brewers friend has a calculator for doing this and some interesting info on refractometer use.

 

[Zephyr259]

@EVVO is correct, alcohol affects the reading of FG so needs to be adjusted. Brewersfriend has an online calculator but I don't like it as it uses their alternate abv formula which gives high readings for strong beers. I've taken the brewer's friend refractometer adjustment sheet and added the calculations at the bottom, have a play if you'd like, just put you refractometer readings in the yellow cells at the bottom left and it'll give you all the other figures.

 

[EVVO]

Sorry for high jacking your thread MrBarrySir but I would like to thank Zephyr259 for his input. I am very much coming from a position of “a little knowledge is dangerous” and will definitely look into his spreadsheet.
Cheers
Steve

 

[Zephyr259]

You're welcome, and I don't think it's too much of a highjack, MrBarrySir will likely have use of the sheet too. Either of you feel free to ask if you have questions about the calcs.

 

[MrBarrySir]

Not a hijack at all! Cheers For the sheet, I'll look into that. I wrongly took the post fermentation refractometer reading at face value and assumed it was correct.

 

[Zephyr259]

No worries, it's a very common thing people do. A lot of "help! I have a stuck fermentation!" threads online start with folks asking if they used a hydrometer or refractometer.

 

[private4587]

I always use my refractometer for all my readings as it is so quick and uses a lot less of your valuable wort. I simply use this calculator which takes not account the alcohol in the wort. I have checked against hydrometer readings and works out fine.