Monday, June 4, 2018

Richard Seale: Pots and Pot Stills or When a Pot Is not a Pot Still

Richard Seale

     Our discussion on wooden vat stills helps illustrate a key concept. Take away the lyne arm, retorts, plates and the condenser and you are left with a vessel not a pot still.  I think that is strikingly obvious in the case of the vat still.   It is the reflux surfaces that define the distillation fundamentals of a pot still. Their shape, position and material effects reflux and thus how the congeners will arrive. Change the shape and the spirit changes. Their shape, position and material determine their catalytic effect when made of copper.
     Harrison et all (2011) found that even when including the shoulder, the effect of copper in the pot section was marginal. This part though above the liquid level will have little reflux because it will be too hot.  Little reflux means little catalytic action. The wooden vat stills did use copper shoulders which would ensure they lacked absolutely no important copper with respect to an all copper still.       Let me reiterate, the point of the previous pot, the wooden vat still lacked for nothing in comparison to an all copper still. That was the genius of the design.
Without the Copper, They are Just Pots
     Harrison et al (2011) found the copper in all areas other than the pot section to have a significant effect on the spirit with the copper in the wash still condenser to be the most important location for copper.  And to the possible positive effect of the wood in the pot section of that sacred cow, I dared to answer, only maybe.  Yes, maybe. Because we do not know the mechanism. It won’t be because of reflux, mainly because none happens here. It won’t be because of a catalytic effect mainly because wood is inert. It could be from another mechanism, it would likely be overwhelmed by the potential variables in the lyne arm, retorts, condenser etc, but we are not ruling the possibility out.
     But most importantly however, we can’t be sure the effect is preferred. Let me give an analog - it is well understood that shell/tube condensers work "better" in that the catalytic effect of the copper is better in a s/t condenser than in a worm tube condenser.  But try to tell those who prefer the "meaty" taste of the worm tub produced whiskies that it is better.  So maybe is my answer.

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