The easiest way to increase the final proof of your still’s output is to pack the column with copper mesh and/or ceramic raschig rings. This still column packing increases the final proof by giving the cool reflux within the column a larger surface area to trickle down and through. As the hot vapor moves up through the column it migrates through the network of distillation column packing material that has the cooler reflux slowly trickling down through it. The slightly lower temperature of the reflux causes the less volatile substances in the vapor (water, fusel oils, etc) to condense out and trickle back down the column. When those components condense out, they heat the cooler reflux causing the more volatile components (the alcohols) to vaporize and travel up the column with the rest of the gasses. So, try and visualize that for a second. Pretty cool, huh?
With this exchange happening, what you end up with is a super-concentrated vapor by the time it gets to the top of the still tower. When done properly with one of our dual-purpose still towers, you can achieve an alcohol by volume of about 95%! However, this isn’t always a good thing, which we will discuss later.
The simple explanation is that moonshine still thumpers help act as a basic second distillation stage. Before they are condensed, the hot vapors are bubbled through a cooler liquid in a separate container. In a similar fashion to what happens inside the reflux tower, the less volatile substances in the vapor (water, fusel oils, etc) condense when they come into contact with the cooler liquid and the more volatile components (the alcohols) in the thumper vaporize as the condensing liquid heats them. So, typically, a thumper will bump your initial run from 100-110 proof to 140-150 proof, and this is all without having to heat and boil something in your still twice which saves both time and money (energy costs)!
However, because the moonshine thumper is essentially only one stage of enrichment, your final proof won’t be as high as the continuous enrichment of the reflux tower. But, with the reflux tower, you are condensing out the reflux and then eventually having to vaporize it again, so you loose that energy efficiency.
What if I am trying to make whiskey, rum, brandy, etc?
A lot of people (mistakenly) think that only a pot still can be used to make good whiskey, rum, brandy, etc. The truth is that most of these products are distilled multiple times and a reflux column and thumper exist to perform multiple distillations in one run. So, by properly using a reflux still or thumper during your whiskey/rum/brandy run, you can save enormous amounts of time and energy.
However, be aware that if you are running a reflux tower at full efficiency, you will be stripping out all the flavor with everything else. This has a very easy solutionH use less column packing!
Now for the science (so skip to the next section if you don’t like science or just don’t care). Each type of column packing material has a Height Equivalent to a Theoretical Plate (HETP). This is the amount (height) of packing that is needed for that material to be equivalent to a plate (for example, one of the bubble plates in our copper bubble plate still tower). Each plate basically serves as a mini-thumper, creating another stage of distillation. The HETP for copper mesh is about 6.1 inches (depending upon the weave and how tightly it is packed) and the HETP for our 6 mm raschig rings is about 9.4 inches. So, if you want to make a traditional Irish whisky (which is usually run through a pot still three times), you could use 5.1 inches of copper (1 HETP) and 9.4 inches of raschig rings (1 HETP) in your column to emulate those 3 runs through a pot still. Nifty!
As with anything distilling related, your tongue and nose have the final say. If you feel like you are stripping to0 much flavor out, take out some more packing. If you feel like you have too much flavor and want to bump up the purity, add some more packing!
What’s all the buzz about copper?
A majority of the old traditional stills you see are made out of copper, and there is certainly a reason for this. Copper will react with the hydrogen sulfide and isobutyl mercaptan vapors and form copper sulfate. This copper sulfate then bonds with fatty acids and oils to eliminate skunky and rotten egg smells, creating a better tasting final product.
So, aside from its very low HETP (a good thing), this is also a great reason to use copper mesh as column packing. We recommend using a pound of copper mesh inside your still column, which should help strip out all those sulfides and other various compounds.
Over time, as the copper reacts with the vapors, it will slowly start turning black. Don’t worry, this is normal! And, even better, the copper can be cleaned and reused. Simply soak the copper mesh in a solution of citric acid and tap water, and in a couple hours you should start seeing the copper color coming through from underneath the blackness. Eventually, the sulfides will react with enough of your copper that you will need to replace it, but it should be good for awhile!
Note: Don’t let the copper/citric acid/water soak together in an aluminum baking pan. It will end up all over your counter once the solution eats through the baking pan. Do I know this from experience? Maybe….
If copper is so awesome, why would I even want raschig rings?
Raschig rings are a column packing made from a ceramic, and thus, basically inert (that is, they don’t react with anything). This is great because you can re-use them over and over again for a lifetime! Over time they will absorb some of the fatty acids and oils that were mentioned above, giving them a slightly funky smell, but luckily these are volatile compounds (they had to boil out of the mash to get there in the first place)! You can simply lay the raschig rings on a cookie tray and bake them in the oven to vaporize all those compounds. On top of that, raschig rings are the cheapest column packing for the amount of space they fill up in your column.
So, copper isn’t the end-all be-all column packing material. That is why we typically recommend packing your tower about 50/50 with copper mesh and raschig rings.
How to Install Copper Mesh and Raschig Rings
Installing your column packing material is very easy, but we’ll save that for another day and explain in depth how to assemble your new column. Check back for a link!