HOMEBREW Digest #232 Sat 19 August 1989
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Rob Gardner, Digest Coordinator
Re: SG different from recipe (Crawford.WBST129)
Re: Hydrometer calibrations (Roger Rose)
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Date: 18 Aug 89 06:32:03 PDT (Friday)
From: Crawford.WBST129 at Xerox.COM
Subject: Re: SG different from recipe
In #231 Patrick Stirling writes:
>On another topic, I have difficulty getting my wort to ferment out all
>the way. I also find that the starting SG is lower than the recipe said
>it would be. I don't have my records to hand but for one attempt at an
>English style bitter, the recipe said it started around 1.060 and finished
>around 1.016. I actually got 1.052 and 1.022 as far as I remember.
The SG will change with the temperature of the sample. Make sure you
read the SG when the sample is at 60 degrees or use the conversion chart
in the back of Papazian (and in other books also).
If you are using the technique of boiling a few gallons and then adding
to serveral more gallons of cold water in the fermenter perhaps the cold
and hot liquids are not mixing properly. I have gotten very low SG
readings before for this very reason.
I think the higher final gravity is most likely due to the yeast.
Everyones conditions during fermentation are different and will cause the
yeast to act differently. The type or brand of yeast may also be a
factor. If the yeast you are using happens to be unattenuative
(flocculates before finishing the fermentation) the Final SG will be
higher. Dave Miller's book gives some characteristics such as
attenuative/unattenuative for a few types of yeast that he has used.
Yeast may also flocculate early because of drastic temperature changes.
Also, in theory if the trub is left in during primary fermentation it
will inhibit the yeast. I have never had a problem but that is the
theory. Does anybody else have any experience with leaving or not
leaving trub in the carboy?
Anyway, if the beer tastes good then that's what really counts.
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Date: Fri, 18 Aug 89 12:32:57 MDT
From: rlr at stcvax.UUCP (Roger Rose)
Subject: Re: Hydrometer calibrations
> From: roberts%studguppy at LANL.GOV (Doug Roberts at Los Alamos National Laboratory)
> My (cheap little) hydrometer
> doesn't say if the alcohol percentages are by weight or volume.
> However, since the specific gravity of a liquid is defined as the
> ratio of it's density with respect to pure water, I would think that
> the alcohol percentages would be weight percents.
Not necessarily so. My hydrometer specifically says % alcohol by volume.
UUCP: rlr at stcvax.stortek.com
USnail: Storage Technology Corp. - MS1169 / Louisville, Co. 80028-1169
phone: (303) 673-6873
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End of HOMEBREW Digest #232, 08/19/89
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