30% loss wouldn't be very good for a commercial outfit. There are a few
possible reasons why you're not getting your 100% conversion rate:
- You don't describe the type of still head you have on your column in
your previous post. If it's a vapour management style head, a la Mike et
Mike's Compleat Distiller book, then you should expect to not collect
tails very easily (cough, ahem, we be talking 'bout alcohol here, of
course...). You'll need to apply a lot more heat than you do during your
main run to collect the tails, otherwise you'll be waiting around for a
very, very, long time.
- 90 degrees C won't be high enough to gather all the ethanol bearing
tails. If you seriously want to gather everything then you'll want to
boil that puppy until you reach 100 degrees. Don't expect a high
concentration of alc in the later 90s, and certainly don't expect it to
taste overly nice.
- Don't expect to collect 100% of the alcohol from the wash, it's just
not going to happen.
- Your hydrometer measurements aren't strictly speaking telling you you
have 10.6% abv, it's telling you that the density of your wash at the
start has dropped by a certain amount, and that if that was *only* sugar
being converted to alcohol then you'll have x% of alcohol. Unfortunately
yeast turn sugar into other stuff too.
- In your other mail you mention the ambient temp is 12 degrees C. If
your spirit is that temp when you measure it then correct it up a bit,
because it's more likely 80% than 76%.
- Ethanol vapour isn't really visible. It will like steam if it's truly
pissing out (i.e., you lost water to condenser at the top of your
column), but you may not notice smaller leaks of vapour. Follow your
nose to see if you can find a possible leak, wrap the area in teflon
tape and see if it gets damp underneath.
Ummm, there are probably hundreds of other possible reasons. It sounds
like you're making a rum -- it might pay just to throw the wash through
on a high-ish heat first time, then redistill it more slowly paying
closer attention to where the heads / tails fall, and blend something
out of that. Anyway, a hobby level isn't it more about producing a
quality spirit than maximal alcohol return?
PS -- re: overloading your still with two batches of rum at once. It's
not worth finding out the hard way, is it? There are so many variables.
If these are your first runs with molasses washes then play safe, run
the smaller batch through first, check inside the still after to see
where it foamed up to, and adjust future batch sizes accordingly. You do
not want to be showered in boiling hot wash.
On Fri, 2004-01-30 at 11:49, jaberie303 wrote:
> Sorry to ask this question again; I probably didn't state it properly
> the first time.
> Using a wort hydrometer and, adjusting for temperature, measuring the
> starting and final gravity, I came up with my 24.8L batch as
> finishing to 10.6%ABV . This calcs to 2.633L of 100% ethanol.
> My TOTAL output up to 90C (including the discarded foreshots) is
> 2.365L with a weighted average of 76%AVB. This calcs to 1.798L of
> 100% ethanol. I lost 31.7% of the ethanol in the mash. What gives?
> I don't see any more leaks. There is a SLIGHT odor of mash/molasses.
> I have resoldered the bitch countless times. I've tested with water
> both during heating and with filling the column and head with water
> and checking for leaks. I put a new cork gasket between the dome and
> 60L keg.
> Is ethanol vapor even visible? Water certainly is.
> Is this output loss normal? What do you lose?
> Thanks again, James