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Old 04-11-2008, 04:25 AM   #5
Mr Fjeld
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Originally Posted by primate77 View Post
In my profession, to "save" the guy anchors in guyed communication towers, "sacrificial" devices are placed in the ground next to the guy anchors
I know they use zinc anodes with boats but I didn't know they use the same technology in building structures? I learned something today

Originally Posted by primate77 View Post
So how is it the copper is sacrificed? Is it high amounts of heat?
Indeed it is! During distillation the liquid & vapours will react with the copper; dissolving parts of it and transform it into copper salts. It's crucial to reduce the amount of sulphur in the new make. Ian Wisniewski, a whisky journalists says it so much better than I but the process of pot still distillation is the same with whisky and rum so here goes some of the most important factors in the process: (it's a very good article so I'm pasting a large part of it - it's from Whisky Magazine Issue 23)
..........During distillation copper absorbs sulphur compounds, converting them into other, less organoleptically active compounds (ie. less sulphur character), while also acting as a catalyst helping to manipulate the ester character. As sulphur compounds feature a distinctive line-up of notes, ranging from struck match, sulphurous, rubbery, meaty and sweaty socks, to cabbage and vegetal, they can easily dominate and ‘conceal’ other characteristics within the new make spirit. While a certain level of sulphur character can be highly desirable, depending on the house style, lowering the level of sulphur compounds allows the congeners, including esters, to show more readily.

The full extent of reactions taking place within the still is unknown, though it’s clear that any action only takes place when congeners touch the copper surface, either as vapour or liquid. (There again, as vapours are hotter than liquid, each reacts slightly differently, though being able to define that difference is another matter). The common denominator is that
components such as organic acid react with copper to create copper salts (verdigris is one example) on the surface of the still neck, and the condenser or worm.

Less than 50 sulphur-bearing compounds (ie. in which sulphur is only an element of the total) have currently been identified, and it remains to be seen how ongoing research affects this total. Some of these compounds have a surprising repertoire, bearing citrus and floral characteristics. As these were only identified a couple of years ago, exactly how they are affected by copper is not yet fully understood. However, it is clear that they only contribute to citrus, floral notes, which are primarily created by esters.

The desirability (or not) and the level of sulphur character required obviously varies considerably between distilleries, and various approaches can promote or discourage the level of copper influence.

The degree of reflux within the still seems like an initial consideration. A higher degree of reflux means more copper
interaction, and so the potential for more copper dissolving into the condensate. However, while vapours presented for a second or third time to the copper surface creates a greater separation of lighter and heavier flavour compounds, and promotes the passage of esters, the crucial question is how much of the dissolved copper actually carries over into the condenser. The answer is a minimal amount..........
"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut."
- Ernest Hemingway

Last edited by Mr Fjeld; 04-11-2008 at 05:17 AM.
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