Surprising US05 attenuation

[imark]

Surprising attenuation on my brew. OG was 1.044 and has dropped to 1.020 after 14 days at 18C. Still krausen on it so I'm not worrying just yet but this is the laziest US05 I've ever had.
Wondering if anybody has had similar experience with recently bought batch?

[imark]

Not infected. I popped the lid and had a good look. It's not krausen. It's just the usual the remnants of the yeasties. I took a sample and measured with my hydrometer and reading came at 1.010. It's done!

Original reading I took with my new refractometer was incorrect. I need to recalibrate. Crisis averted and US05's reputation is restored as the this brewer's workhorse. 

[imark]

Once fermentation has started you can't use the refractometer any more.

Didn't know that. Thought it was a piece of junk. Thanks.

[mr hoppy]

There are is a correction formula for using refractometers once you've started fermenting. I think Jacob posted it on beoir at one stage and IIRC it's also in beersmith. In fact if you use a refractometer and a hydrometer on finished beer you can reverse engineer it and get the OG, FG and alcohol content all in one go.

[mr hoppy]

Last post on this page has the correction formula. Bit fiddly but as I said I think it's in beersmith as well.

[mr hoppy]

That's good to know.

Tube, did you try the finall gravity / refractometer / hydrometer tool in beersmith?

[Greg2013]

Is there any instrument that when used on finished beer will tell you the abv? Don't the wine boys have something? :-/

[Greg2013]

Ya but what are they called?

[Will_D]

Ya but what are they called?

Your e-bay search is for GLC machines: Gas Liquid Chromatography and maybe MS machines: Mass Spectrometer.

These will give you a fairly acurate measure.


Another way is called "The Revenue Method" which is a simple distillation technique. (PM me for the details)

The little glass wine tester is called a vinometer and works by a combination of surface tension and gravity of alcohol water mix as typified in a wine. Its not very accurate but its cheap!!