Lava Rock, a porous volcanic rock, has gained popularity as a packing material in distillation columns. This article explores the effectiveness of lava rock compared to traditional copper mesh packing, based on extensive testing in a 2-inch diameter column.
The initial tests involved a 36-inch packed column using copper mesh, consistently yielding 95% ABV (alcohol by volume) following established distillation practices. Subsequently, the column was packed with dime and nickel-sized lava rock pieces, achieving a comparable result: a clean, azeotropic neutral spirit. This suggests that lava rock can produce a high-purity distillate similar to copper.
Further experimentation involved reducing the copper packing to 16 inches and running an UJ (unspecified, likely a sugar wash) for flavor retention. This resulted in a 90% ABV spirit with desirable flavor characteristics. Repeating the process with 16 inches of lava rock yielded nearly identical results: 90% ABV and comparable flavor profiles. This indicates that lava rock performs similarly to copper in preserving the congeners responsible for flavor in lower ABV spirits.
A comparison was then made using a 4-plate column with the same UJ wash, producing a 93% ABV spirit with robust flavor. This suggests that the flavor differences between theoretical plates (packing) and actual plates may stem more from operational variations than the type of column internals. Fluted or plated columns, in their standard configurations, are inherently efficient at flavor production. This highlights that achieving specific flavor profiles depends on various factors beyond just the packing material.
Ongoing experiments include testing lava rock and copper mesh in a larger, 36-inch by 4-inch column. Modular sections for the plated column are also under development to further compare plates and packing. This demonstrates a commitment to rigorous testing and continuous improvement in distillation techniques.
The modularity of a still allows for flexibility in producing both neutral spirits and flavor-rich products by adapting the column configuration. This versatility is advantageous for distillers seeking to create a variety of spirits.
While precise HETP (Height Equivalent to a Theoretical Plate) calculations for lava rock are complex, estimations suggest it provides approximately 15 plates per meter, indicating good separation efficiency. The efficiency of a 2-inch column can be further enhanced by increasing its height, optimizing packing density, and considering other operational variables. Larger diameter columns (3 inches and above) using lava rock have consistently shown promising results, particularly in producing cleaner spirits. These findings suggest that lava rock is a viable packing material for various still sizes and desired outcomes.
