Reading a refractometer after fermentation

[Velnerj]

Hello homebrew community!

I've been brewing for about a year now and I keep running into the same problem: reading my refractometer during/after fermentation.

Here are some things I understand:

1. Refractometer readings need to be adjusted when alcohol is present.
2. Final readings are best with hydrometer

I usually use the refractometer to take readings to test if fermentation has finished. Did I hit my expected fg? Has fg been stable for several days?etc. I take a hydrometer reading after bottling to get a precise picture and to compare my refractometer readings.

Here's my issue: it's difficult for me to accurately read my refractometer during/after fermentation. The blue line is not so clear to know the exact brix reading. (see pic.)

Does anyone else have this issue? What brix reading would you give the pic?

 

[jack13]

I only use it to see if fermentation seems to be done, by looking for stable readings over 2-3 days. Yeah, sometimes that line is nice and crisp and other times not. I've no idea why, but I'm interested to see if there's a way to fix that. My reading of yours would be 7.1.

 

[day_trippr]

I see 7.8

Cheers!

 

[PoppinCaps]

It may help to degas the sample. Take a slightly larger sample and shake it for a while. Should help clear the line a bit.

 

[Velnerj]

It may help to degas the sample. Take a slightly larger sample and shake it for a while. Should help clear the line a bit.

Never thought about that. I'll definitely give it a try.

 

[ancientmariner52]

Lighting may be the issue here. The instruction sheet with mine recommends natural light, but any strong white light source should work. To get consistent results from any optical instrument, you need consistent lighting.

You should not try to calibrate with alcohol present. Calibrate to zero with distilled water. The things are built to work with solutions of water and sugar. Wort is pretty much that, but alcohol has a different effect on light and skews the readings. You are correct to take a final hydrometer reading to get the true FG.

 

[stickyfinger]

sometimes if you let the sample sit awhile, some yeast and other stuff will settle. take only the clearest liquid. i think the non-crisp line is mainly due to particulates in the sample.