How can this be possible?

[guypettigrew]

On Friday 25th May I brewed a beer with 4Kg pale malt, 1kg Vienna malt, 300g pale crystal malt and 150g flaked oats. Plus some hops!!

I ended up with 23 litres at a brix of 14.3, gravity 1.058. Gravity checked with a hydrometer after the brix>gravity calculation done. The hydrometer and refractometer match.

Today, after cooling to 10C for 36 hours, I've collected the yeast for the next brew and checked the Brix. It's 6.2.

According to the 'Northern Brewer' site this gives me a current gravity of 1.004 and an alcohol content of 7.092%.

This simply cannot be right, or can it?

Advice, please.

Guy

[Jim]

Have you not cross-checked with your hydrometer? Refractometers are notoriously hit and miss when alcohol is present.

[guypettigrew]

Good plan. The refractometer and hydrometer matched at the beginning of fermentation, but perhaps not now.

I'll go and run off 100ml and check it.

Get back to you soon.

Guy

[steviebobs83]

I've had some refractometer issues myself recently and have found the brewers friend site to be very useful. They also allow for a wort correction factor which can make a difference to the final reading. It's a bit of a faff to get it but if you want to get reliable results it's worth it.

https://www.brewersfriend.com/refractometer-calculator/


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[guypettigrew]

The Northern Brewer site has correction factors. It's worth a look.

As to checking with a hydrometer. Difficult. The 100ml run out of the dump valve on my chronical is basically just a yeasty suspension. Mind you, the hydrometer sunk right down. Impossible to read it, though. Too much yeasty froth.

Tomorrow the beer will be going into a King Keg. Should be easy enough to get both a refractometer and hydrometer reading then.

Guy

[steviebobs83]

I have a friend who says I should wear an eye patch, a wooden leg and say "argh!" whenever I use mine.

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[guypettigrew]

That would do it!

Sometimes I wonder if I should give up on all this technical stuff. Watching the bubbles coming from the blow off tube has always served me well.

Guy

[BigMouth]

Wow, that OG and FG do give you a 7.09% beer.
That is a good efficiency first off from 5.3 kg of fermentable malt but to get down to 1.0004 in a week you have a strong, thin beer so I wonder at the yeast and temp during fermentation if the figures are right. It's not unheard of.

I take the OG when I collect the wort just before pitching yeast and the FG before I rack to secondary while sat on the yeast cake. Both are room temperature ish. Cool wort to 20-25C to pitch or OG and take FG at room temperature fermentation, again 18-20C. I use the same hydrometer for both readings too. Partly cos I only have one.
You said you cooled to 10C before checking FG and only with a refractometer. Is this 1.004 comparable to the temp of your OG reading? Conversions phar!

Jim is, of course, right. Make sure your sample is at a temp comparable to that of your OG reading and check with the same hydrometer. I'll believe that figure.

The other option is like a did a month back when I forget to take an OG, I still took an FG and guessed based on the malt bill and experience and sampling.
When you taste it you'll know if it's 7% or 5%.

[simple one]

The only time I have made a wort that fermentable was when I did over night mashes.

Otherwise the only other thing I can think of is an error, a very punchy yeast or maybe an infection.

[Secla]

I was going to suggest possible infection
Did you taste it ?

[guypettigrew]

The hydrometer reads 1.006/8 A bit higher than the calculation from the refractometer reading.

It tastes fine--for a beer which is only 10 days old and kegged yesterday!

The liquor was treated to give 20ppm alkalinity for the mash and 10ppm for the sparge.

I calculated mash efficiency as 92% and overall efficiency as 83%.

The yeast was WLP001, second pitching. Temperature maintained at 19.5C +/- 0.5C.

Perhaps I've just struck lucky!!

Guy