Overattenuation Issue

[Kickass]

actual 147. I added a second infusion to top it to 152

That’s a pretty fermentable mash schedule, very fermentable.

Something strange is going on

Maybe. Maybe not. Continue to monitor and taste. If it tastes good, it’s likely not worth fretting over.

Sometimes yeast are just gonna yeast.

 

[micraftbeer]

I find when I mash at low temps, the FG typically comes out lower than brewing software predicts, by a couple points.

 

[Komodo]

Just out of curiosity, which refractometer calculator?

That’s a good question. I don’t remember, but knowing me I probably used a couple to cross reference if the numbers were off. I had already worked up a correction factor and everything else has been right on with mine.

I was doing a temp step fast lager, and thought it was working great. It looked like it had stalled way too early, so did a hydrometer check and was shocked it was done already. Happy, but surprised.

 

[VikeMan]

That’s a good question. I don’t remember, but knowing me I probably used a couple to cross reference if the numbers were off. I had already worked up a correction factor and everything else has been right on with mine.

The correction factor, i.e. Wort Correction Factor (WCF) accounts for the fact that the sugars/dextrins in wort are mostly not sucrose (which is the sugar that our refractometers are made for). The WCF is fairly important, but when it comes to post fermentation (or during fermentation) readings, it takes a back seat to the fact that alcohol and water have different refractive indexes. That's where using a proper refractometer calculator comes in, i.e. one where the original and final readings are entered together, and not a simple "brix to specific gravity" conversion formula, even one with a correction factor (which will most definitely give an incorrect, "stuck fermentation-like" answer).

I'm not saying that this was the case with your calculations, but since you don't remember what you used, I thought I'd mention it.

 

[dmtaylor]

The correction factor, i.e. Wort Correction Factor (WCF) accounts for the fact that the sugars/dextrins in wort are mostly not sucrose (which is the sugar that our refractometers are made for). The WCF is fairly important, but when it comes to post fermentation (or during fermentation) readings, it takes a back seat to the fact that alcohol and water have different refractive indexes. That's where using a proper refractometer calculator comes in, i.e. one where the original and final readings are entered together, and not a simple "brix to specific gravity" conversion formula, even one with a correction factor (which will most definitely give an incorrect, "stuck fermentation-like" answer).

I'm not saying that this was the case with your calculations, but since you don't remember what you used, I thought I'd mention it.

+1.

There is definitely a right way and a wrong way to use a refractometer. Unfortunately, millions of people use it the wrong way and then poo-poo it, which understandably annoys the other millions who use it the right way. We cannot know which side you are on without specific data.

 

[VikeMan]

There is definitely a right way and a wrong way to use a refractometer.

It's a very sticky/FAQ worthy topic IMO. Not that most people (me included) read sticky posts before asking/commenting anyway, but at least if they existed, folks could point to them instead of retyping ad infinitum.

 

[MicroMickey]

https://crescentcitybrewtalk.com/attenuation-2/The last sentence of this article sums it up.