Re: [new_distillers] aluminum pot
- Great post! Enough with the witchhunt,!Sent from my Verizon Wireless BlackBerryFrom: Robert Hubble <zymurgybob@...>Sender: firstname.lastname@example.orgDate: Sat, 27 Jul 2013 17:16:16 -0700To: email@example.com<firstname.lastname@example.org>ReplyTo: email@example.comSubject: RE: [new_distillers] aluminum potRLB,
Sorry to be slow chiming in here, but yes, I do advocate the use of aluminum pressure cookers (not stock pots, they're way too flimsy) as a beginner's still boiler. Just for the record, I've heard Tony Ackland, the original founder of these 2 lists and a renown authority, also admit that he used aluminum boilers with no adverse effect, although he evidently took a lot of crap from other distillers, pretty much the same as now.
As far as corrosion resistance goes, with no pH fiddling whatsoever, I used my first 5-gallon aluminum boiler still for years, with no apparent changes in the condition of the metal, although I'll admit it was slightly rough when I started using it (and also when I finished). The only surface deterioration I experience was due to the fact that during a move, the boiler got put away for a few years with a spent wash inside, and because it was a gasketless design which sealed by forcing 2 conical sufaces together, those conical surfaces sort of seized to each other, not allowing the lid to be removed.
After a few days of applying boiling water and a rubber mallet, the lid came free. After cleaning everything up with a Brillo pad, I put that still into use for another couple of years before I sold it, thinking I would no longer be a distiller. When I started up again a few years later, I used another 5-gallon aluminum pressure cooker, and I've made a couple more for friends.
As far as flavor, the best bourbon I've ever made was made on an aluminum-boiler still (which is now in service with a satisfied friend), and that bourbon beat a lot of the big names you'd respect in blind taste testing, so you'll never convince me that the flavor is bad. If someone got bad-flavored distillate from an aluminum boiler, I'm guessing one of the nasty-tasting turbos was at fault, not the aluminum
One reason that aluminum is good as a boiler is that in distillation, only the volatiles come through the output condenser, and aluminum does not form volatile compounds except in lab-curiosity reactions, not in heated wash, so no aluminum comes through the still. Admittedly, I do not not, and would not, brew beer in aluminum, because beer-making does not separate out the non-volatiles from the wort/wash.
Is stainless "better" than aluminum for a boiler? Probably, and I'm guessing that platinum would be even better, but unless you're driving nothing but Bugattis, you're probably sensitive to the cost-benefit curve, as many of us are, and aluminum pressure-cooker boilers make a fine beginner's low-cost still.
Zymurgy Bob, a simple potstiller
Date: Sat, 27 Jul 2013 02:20:38 -0700
Subject: Re: [new_distillers] aluminum pot
I have been eyeing an All American aluminum pressure canner as a still, and I have heard a number of adverse things about using aluminum. What you wrote gave me an idea to test an aluminum pot. If acidity might cause erosion, why not decrease acidity before running your wash. You need wash to be about 5 ph to ferment properly, so it would be easy to increase your to 8 ph just before a stripping run. Just a thought
From: Zapata Vive <zapatavive@...>
Sent: Friday, July 26, 2013 11:51 PM
Subject: Re: [new_distillers] aluminum pot
Pretty sure ZBob has made a lot of booze in aluminum pressure cookers and noted no faults, nor the oft cited pitting, unless something has cropped up in the last year or two.
I just read a journal article "Corrosion characteristics of aluminum alloy in bio-ethanol blended" . They found corrosion in up to 20% ethanol (highest percentage tested) after 24 hours at pressure and 100*C. Lower temps showed no corrosion. I imagine something more exciting is going to happen if you get a pressure cooker still with a 20% ABV charge up to 100*C
I think at least so far as corrosion goes it would be sufficient to not let setback sit around in your cooker and rinse it out when your done.
So far as off tastes go, I have no idea, but Zbob didn't mention it in Making Fine Spirits, where he endorses aluminum pressure cookers.
All that being said, I've often eyeballed my 10 gallon All American 1941X and thought it'd make a fine boiler, but no way would I take even the smallest chance in a $700 pot! Been meaning to try it for myself on one of my smaller PCs to work out fine details on test size batches, but I have trouble motivating myself to put in the hard work of small tests.
So have ya'll actually tried it and seen pitting/gotten off tastes, or just heard about it?On Fri, Jul 26, 2013 at 11:52 AM, Jim Graves <jimbull34@...> wrote:The alcohol reacts with the aluminum and gives a very, VERY bad taste to it plus it errodes the pot! Don't use, old pressure cooker were cast steel, the new ones ore cast aluminum, don't use 'um.
(Short version: Aluminum oxides react with acids and facilitate alcohol oxidation reactions. Some of the byproducts of these reactions aren't so good. Unless producing max-purity etoh, why not play safe and use anodized aluminum, which is non reactive?)
Disclaimer: not a chemist, nor chemEng. These are reasoned opinions, that you may refute or extend.
Newbie here who's done a bunch of reading on this subject, and can't find a whole lot of well-argued conclusions. But there is a lot of data. The key is to examine the reactivity of Al with all the compounds found in the wash. What those reactions can produced, whether they'll make it into the distillate, and whether the by products are healthy or not.
Aluminum oxide (the surface) is pretty reactive and creates some nasty byproducts.
The aluminum oxide formed naturally on the surface of the aluminum reacts with ethanol to produce ethene (ethylene).
Ethene is pretty widely used, but isn't terribly great for humans. But, the other alcohols in the wash will form other alkenes, by the same reaction. The boiling points of the alkenes are either well below or well above the range of etoh distallates.
It seems that ethoxide and methoxide salts of alumimum can be formed, as well. These are hazardous substances. But in what proportion are they formed? And will they make it into the distallate? BPs are hundreds of degrees C.
In acids with the presence of chlorine (is your water chlorinated)? Aluminum chloride is formed --http://www.chemguide.co.uk/inorganic/period3/oxidesh2o.html -- a neurotoxin. BP 120C but soluble in both ethanol and water. http://en.wikipedia.org/wiki/Aluminum_chloride
Ketones, aldehydes, esters all participate in some reactions with aluminum salts.
---In firstname.lastname@example.org, <last2blast@...> wrote:In truth, we can't compare an aluminum engine to an aluminum pot for several reasons friction, heat, and constant exposure to ethanol under adverse conditions. There is potential for low Ph levels to cause some eventual erosion of any metal over time, but the real question is whether that extremely small amount of trace metal can be transferred from pot to distillate? FDA labels distilled water as purified for a very good reason, and if you distill properly there will be nothing but distilled water and ethanol in your jars.Robert
From: Zapata Vive <zapatavive@...>
Sent: Friday, November 22, 2013 10:11 AM
Subject: Re: Re: [new_distillers] aluminum pot
So the labs say aluminun is corroded by ethanol. But first hand use in our hobby reports minimal to nonexistant corrosion. At that, the labs modeling car parts say the corrosion is formed by a reaction between ethanol and aluminum, forming aluminum ethoxide before drying. BP for aluminum ethoxide? 320ºc, im not concerned, but we all choose for ourselves....On Nov 21, 2013 6:56 PM, "Wes" <yhetti@...> wrote: